gl4/glBlendFunc.xhtml

    <div class="refentry" id="glBlendFunc">
      <div class="titlepage"></div>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glBlendFunc — specify pixel arithmetic</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glBlendFunc</strong>(</code>
              </td>
              <td>GLenum <var class="pdparam">sfactor</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">dfactor</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glBlendFunci</strong>(</code>
              </td>
              <td>GLuint <var class="pdparam">buf</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">sfactor</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">dfactor</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>buf</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    For <code class="function">glBlendFunci</code>, specifies the index of the draw
                    buffer for which to set the blend function.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>sfactor</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies how the red, green, blue,
                    and alpha source blending factors are computed.
                    The initial value is <code class="constant">GL_ONE</code>.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>dfactor</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies how the red, green, blue,
                    and alpha destination blending factors are computed.
                    The following symbolic constants are accepted:
                    <code class="constant">GL_ZERO</code>,
                    <code class="constant">GL_ONE</code>,
                    <code class="constant">GL_SRC_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_SRC_COLOR</code>,
                    <code class="constant">GL_DST_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_DST_COLOR</code>,
                    <code class="constant">GL_SRC_ALPHA</code>,
                    <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>,
                    <code class="constant">GL_DST_ALPHA</code>,
                    <code class="constant">GL_ONE_MINUS_DST_ALPHA</code>.
                    <code class="constant">GL_CONSTANT_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>,
                    <code class="constant">GL_CONSTANT_ALPHA</code>, and
                    <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code>.
                    The initial value is <code class="constant">GL_ZERO</code>.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            Pixels can be drawn using a function that blends
            the incoming (source) RGBA values with the RGBA values
            that are already in the frame buffer (the destination values).
            Blending is initially disabled.
            Use <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> with argument <code class="constant">GL_BLEND</code>
            to enable and disable blending.
        </p>
        <p>
            <code class="function">glBlendFunc</code> defines the operation of blending for all draw buffers when it is enabled.
            <code class="function">glBlendFunci</code> defines the operation of blending for a single draw buffer
            specified by <em class="parameter"><code>buf</code></em> when enabled for that draw buffer.
            <em class="parameter"><code>sfactor</code></em> specifies which method is used to scale the
            source color components.
            <em class="parameter"><code>dfactor</code></em> specifies which method is used to scale the
            destination color components.
            Both parameters must be one of the following symbolic constants:
                    <code class="constant">GL_ZERO</code>,
                    <code class="constant">GL_ONE</code>,
                    <code class="constant">GL_SRC_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_SRC_COLOR</code>,
                    <code class="constant">GL_DST_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_DST_COLOR</code>,
                    <code class="constant">GL_SRC_ALPHA</code>,
                    <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>,
                    <code class="constant">GL_DST_ALPHA</code>,
                    <code class="constant">GL_ONE_MINUS_DST_ALPHA</code>,
                    <code class="constant">GL_CONSTANT_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>,
                    <code class="constant">GL_CONSTANT_ALPHA</code>,
                    <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code>,
                    <code class="constant">GL_SRC_ALPHA_SATURATE</code>,
                    <code class="constant">GL_SRC1_COLOR</code>,
                    <code class="constant">GL_ONE_MINUS_SRC1_COLOR</code>,
                    <code class="constant">GL_SRC1_ALPHA</code>, and
                    <code class="constant">GL_ONE_MINUS_SRC1_ALPHA</code>.
            The possible methods are described in the following table.
            Each method defines four scale factors,
            one each for red, green, blue, and alpha.
            In the table and in subsequent equations, first source, second source
            and destination color components are referred to as
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">s0</mi>
                    </msub>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">s0</mi>
                    </msub>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">s0</mi>
                    </msub>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">s0</mi>
                    </msub>
                </mfenced>
            </math>,
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">s1</mi>
                    </msub>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">s1</mi>
                    </msub>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">s1</mi>
                    </msub>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">s1</mi>
                    </msub>
                </mfenced>
            </math>
            and
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                </mfenced>
            </math>, respectively.
            The color specified by <a class="citerefentry" href="glBlendColor"><span class="citerefentry"><span class="refentrytitle">glBlendColor</span></span></a> is referred to as
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">c</mi>
                    </msub>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">c</mi>
                    </msub>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">c</mi>
                    </msub>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">c</mi>
                    </msub>
                </mfenced>
            </math>.
            They are understood to have integer values between 0 and
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">k</mi>
                    <mi mathvariant="italic">R</mi>
                    </msub>
                    <msub><mi mathvariant="italic">k</mi>
                    <mi mathvariant="italic">G</mi>
                    </msub>
                    <msub><mi mathvariant="italic">k</mi>
                    <mi mathvariant="italic">B</mi>
                    </msub>
                    <msub><mi mathvariant="italic">k</mi>
                    <mi mathvariant="italic">A</mi>
                    </msub>
                </mfenced>
            </math>,
            where
        </p>
        <p>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">k</mi>
                    <mi mathvariant="italic">c</mi>
                    </msub>
                    <mo>=</mo>
                    <mrow>
                        <msup><mn>2</mn>
                        <mfenced open="" close="">
                            <msub><mi mathvariant="italic">m</mi>
                            <mi mathvariant="italic">c</mi>
                            </msub>
                        </mfenced>
                        </msup>
                        <mo>-</mo>
                        <mn>1</mn>
                    </mrow>
                </mrow>
            </math>
        </p>
        <p>
            and
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">m</mi>
                    <mi mathvariant="italic">R</mi>
                    </msub>
                    <msub><mi mathvariant="italic">m</mi>
                    <mi mathvariant="italic">G</mi>
                    </msub>
                    <msub><mi mathvariant="italic">m</mi>
                    <mi mathvariant="italic">B</mi>
                    </msub>
                    <msub><mi mathvariant="italic">m</mi>
                    <mi mathvariant="italic">A</mi>
                    </msub>
                </mfenced>
            </math>
            is the number of red,
            green,
            blue,
            and alpha bitplanes.
        </p>
        <p>
            Source and destination scale factors are referred to as
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">s</mi>
                    <mi mathvariant="italic">R</mi>
                    </msub>
                    <msub><mi mathvariant="italic">s</mi>
                    <mi mathvariant="italic">G</mi>
                    </msub>
                    <msub><mi mathvariant="italic">s</mi>
                    <mi mathvariant="italic">B</mi>
                    </msub>
                    <msub><mi mathvariant="italic">s</mi>
                    <mi mathvariant="italic">A</mi>
                    </msub>
                </mfenced>
            </math>
            and
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">d</mi>
                    <mi mathvariant="italic">R</mi>
                    </msub>
                    <msub><mi mathvariant="italic">d</mi>
                    <mi mathvariant="italic">G</mi>
                    </msub>
                    <msub><mi mathvariant="italic">d</mi>
                    <mi mathvariant="italic">B</mi>
                    </msub>
                    <msub><mi mathvariant="italic">d</mi>
                    <mi mathvariant="italic">A</mi>
                    </msub>
                </mfenced>
            </math>.
            The scale factors described in the table,
            denoted
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">f</mi>
                    <mi mathvariant="italic">R</mi>
                    </msub>
                    <msub><mi mathvariant="italic">f</mi>
                    <mi mathvariant="italic">G</mi>
                    </msub>
                    <msub><mi mathvariant="italic">f</mi>
                    <mi mathvariant="italic">B</mi>
                    </msub>
                    <msub><mi mathvariant="italic">f</mi>
                    <mi mathvariant="italic">A</mi>
                    </msub>
                </mfenced>
            </math>,
            represent either source or destination factors.
            All scale factors have range
            <math overflow="scroll">

                <mfenced open="[" close="]">
                    <mn>0</mn>
                    <mn>1</mn>
                </mfenced>
            </math>.
        </p>
        <p>
        </p>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: left; "/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                            <span class="bold"><strong> Parameter </strong></span>
                        </th>
                <th style="text-align: left; border-bottom: 2px solid ; ">
                            <math overflow="scroll">

                                <mfenced open="(" close=")">
                                    <msub><mi mathvariant="italic">f</mi>
                                    <mi mathvariant="italic">R</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">f</mi>
                                    <mi mathvariant="italic">G</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">f</mi>
                                    <mi mathvariant="italic">B</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">f</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfenced>
                            </math>
                        </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                            <code class="constant">GL_ZERO</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mn>0</mn>
                                <mn>0</mn>
                                <mn>0</mn>
                                <mn>0</mn>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mn>1</mn>
                                <mn>1</mn>
                                <mn>1</mn>
                                <mn>1</mn>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_SRC_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">R</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">R</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">G</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">G</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">B</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">B</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_SRC_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">R</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">R</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">G</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">G</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">B</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">B</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_DST_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">R</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">R</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">G</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">G</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">B</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">B</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_DST_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">R</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">R</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">G</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">G</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">B</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">B</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_SRC_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s0</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s0</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_DST_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_DST_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">d</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_CONSTANT_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <msub><mi mathvariant="italic">R</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">G</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">B</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <msub><mi mathvariant="italic">R</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">G</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">B</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_CONSTANT_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">c</mi>
                                </msub>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">c</mi>
                                    </msub>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_SRC_ALPHA_SATURATE</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mi mathvariant="italic">i</mi>
                                <mi mathvariant="italic">i</mi>
                                <mi mathvariant="italic">i</mi>
                                <mn>1</mn>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_SRC1_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">R</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">R</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">G</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">G</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">B</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">B</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_SRC1_COLOR</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">R</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">R</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">G</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">G</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">B</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">B</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                        <code class="constant">GL_SRC1_ALPHA</code>
                        </td>
                <td style="text-align: left; border-bottom: 2px solid ; ">
                        <math overflow="scroll">

                            <mfenced open="(" close=")">
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                                <mfrac>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">s1</mi>
                                    </msub>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                </mfrac>
                            </mfenced>
                        </math>
                        </td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                        <code class="constant">GL_ONE_MINUS_SRC1_ALPHA</code>
                        </td>
                <td style="text-align: left; ">
                        <math overflow="scroll">

                            <mrow>
                                <mfenced open="(" close=")">
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                    <mn>1</mn>
                                </mfenced>
                                <mo>-</mo>
                                <mfenced open="(" close=")">
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                    <mfrac>
                                        <msub><mi mathvariant="italic">A</mi>
                                        <mi mathvariant="italic">s1</mi>
                                        </msub>
                                        <msub><mi mathvariant="italic">k</mi>
                                        <mi mathvariant="italic">A</mi>
                                        </msub>
                                    </mfrac>
                                </mfenced>
                            </mrow>
                        </math>
                        </td>
              </tr>
            </tbody>
          </table>
        </div>
        <p>
            In the table,
        </p>
        <p>
            <math overflow="scroll">

                <mrow>
                    <mi mathvariant="italic">i</mi>
                    <mo>=</mo>
                    <mfrac>
                        <mrow>
                            <mi mathvariant="italic">min</mi>
                            <mo>⁡</mo>
                            <mfenced open="(" close=")">
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">s</mi>
                                </msub>
                                <mrow>
                                    <msub><mi mathvariant="italic">k</mi>
                                    <mi mathvariant="italic">A</mi>
                                    </msub>
                                    <mo>-</mo>
                                    <msub><mi mathvariant="italic">A</mi>
                                    <mi mathvariant="italic">d</mi>
                                    </msub>
                                </mrow>
                            </mfenced>
                        </mrow>
                        <msub><mi mathvariant="italic">k</mi>
                        <mi mathvariant="italic">A</mi>
                        </msub>
                    </mfrac>
                </mrow>
            </math>
        </p>
        <p>
            To determine the blended RGBA values of a pixel,
            the system uses the following equations:
        </p>
        <p>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <mrow>
                        <mi mathvariant="italic">min</mi>
                        <mo>⁡</mo>
                        <mfenced open="(" close=")">
                            <msub><mi mathvariant="italic">k</mi>
                            <mi mathvariant="italic">R</mi>
                            </msub>
                            <mrow>
                                <msub><mi mathvariant="italic">R</mi>
                                <mi mathvariant="italic">s</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">s</mi>
                                <mi mathvariant="italic">R</mi>
                                </msub>
                                <mo>+</mo>
                                <msub><mi mathvariant="italic">R</mi>
                                <mi mathvariant="italic">d</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">d</mi>
                                <mi mathvariant="italic">R</mi>
                                </msub>
                            </mrow>
                        </mfenced>
                    </mrow>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <mrow>
                        <mi mathvariant="italic">min</mi>
                        <mo>⁡</mo>
                        <mfenced open="(" close=")">
                            <msub><mi mathvariant="italic">k</mi>
                            <mi mathvariant="italic">G</mi>
                            </msub>
                            <mrow>
                                <msub><mi mathvariant="italic">G</mi>
                                <mi mathvariant="italic">s</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">s</mi>
                                <mi mathvariant="italic">G</mi>
                                </msub>
                                <mo>+</mo>
                                <msub><mi mathvariant="italic">G</mi>
                                <mi mathvariant="italic">d</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">d</mi>
                                <mi mathvariant="italic">G</mi>
                                </msub>
                            </mrow>
                        </mfenced>
                    </mrow>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <mrow>
                        <mi mathvariant="italic">min</mi>
                        <mo>⁡</mo>
                        <mfenced open="(" close=")">
                            <msub><mi mathvariant="italic">k</mi>
                            <mi mathvariant="italic">B</mi>
                            </msub>
                            <mrow>
                                <msub><mi mathvariant="italic">B</mi>
                                <mi mathvariant="italic">s</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">s</mi>
                                <mi mathvariant="italic">B</mi>
                                </msub>
                                <mo>+</mo>
                                <msub><mi mathvariant="italic">B</mi>
                                <mi mathvariant="italic">d</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">d</mi>
                                <mi mathvariant="italic">B</mi>
                                </msub>
                            </mrow>
                        </mfenced>
                    </mrow>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <mrow>
                        <mi mathvariant="italic">min</mi>
                        <mo>⁡</mo>
                        <mfenced open="(" close=")">
                            <msub><mi mathvariant="italic">k</mi>
                            <mi mathvariant="italic">A</mi>
                            </msub>
                            <mrow>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">s</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">s</mi>
                                <mi mathvariant="italic">A</mi>
                                </msub>
                                <mo>+</mo>
                                <msub><mi mathvariant="italic">A</mi>
                                <mi mathvariant="italic">d</mi>
                                </msub>
                                <mo>⁢</mo>
                                <msub><mi mathvariant="italic">d</mi>
                                <mi mathvariant="italic">A</mi>
                                </msub>
                            </mrow>
                        </mfenced>
                    </mrow>
                </mrow>
            </math>
        </p>
        <p>
            Despite the apparent precision of the above equations,
            blending arithmetic is not exactly specified,
            because blending operates with imprecise integer color values.
            However,
            a blend factor that should be equal to 1
            is guaranteed not to modify its multiplicand,
            and a blend factor equal to 0 reduces its multiplicand to 0.
            For example,
            when <em class="parameter"><code>sfactor</code></em> is <code class="constant">GL_SRC_ALPHA</code>,
            <em class="parameter"><code>dfactor</code></em> is <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>,
            and
            <math overflow="scroll">

                <msub><mi mathvariant="italic">A</mi>
                <mi mathvariant="italic">s</mi>
                </msub>
            </math>
            is equal to
            <math overflow="scroll">

                <msub><mi mathvariant="italic">k</mi>
                <mi mathvariant="italic">A</mi>
                </msub>
            </math>,
            the equations reduce to simple replacement:
        </p>
        <p>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <msub><mi mathvariant="italic">R</mi>
                    <mi mathvariant="italic">s</mi>
                    </msub>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <msub><mi mathvariant="italic">G</mi>
                    <mi mathvariant="italic">s</mi>
                    </msub>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <msub><mi mathvariant="italic">B</mi>
                    <mi mathvariant="italic">s</mi>
                    </msub>
                </mrow>
            </math>
            <math overflow="scroll">

                <mrow>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">d</mi>
                    </msub>
                    <mo>=</mo>
                    <msub><mi mathvariant="italic">A</mi>
                    <mi mathvariant="italic">s</mi>
                    </msub>
                </mrow>
            </math>
        </p>
        <p>
        </p>
      </div>
      <div class="refsect1" id="examples">
        <h2>Examples</h2>
        <p>
        </p>
        <p>
            Transparency is best implemented using blend function
            (<code class="constant">GL_SRC_ALPHA</code>, <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>)
            with primitives sorted from farthest to nearest.
            Note that this transparency calculation does not require
            the presence of alpha bitplanes in the frame buffer.
        </p>
        <p>
            Blend function
            (<code class="constant">GL_SRC_ALPHA</code>, <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>)
            is also useful for rendering antialiased points and lines
            in arbitrary order.
        </p>
        <p>
            Polygon antialiasing is optimized using blend function
            (<code class="constant">GL_SRC_ALPHA_SATURATE</code>, <code class="constant">GL_ONE</code>)
            with polygons sorted from nearest to farthest.
            (See the <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, <a class="citerefentry" href="glDisable"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> reference page and the
            <code class="constant">GL_POLYGON_SMOOTH</code> argument for information on polygon antialiasing.)
            Destination alpha bitplanes,
            which must be present for this blend function to operate correctly,
            store the accumulated coverage.
        </p>
      </div>
      <div class="refsect1" id="notes">
        <h2>Notes</h2>
        <p>
            Incoming (source) alpha is correctly thought of as a material opacity,
            ranging from 1.0
            (<math overflow="scroll">

                <msub><mi mathvariant="italic">K</mi>
                <mi mathvariant="italic">A</mi>
                </msub>
            </math>),
            representing complete opacity,
            to 0.0 (0), representing complete
            transparency.
        </p>
        <p>
            When more than one color buffer is enabled for drawing,
            the GL performs blending separately for each enabled buffer,
            using the contents of that buffer for destination color.
            (See <a class="citerefentry" href="glDrawBuffer"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>.)
        </p>
        <p>
            When dual source blending is enabled (i.e., one of the blend factors requiring
            the second color input is used), the maximum number of enabled draw buffers
            is given by <code class="constant">GL_MAX_DUAL_SOURCE_DRAW_BUFFERS</code>, which may
            be lower than <code class="constant">GL_MAX_DRAW_BUFFERS</code>.
        </p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if either <em class="parameter"><code>sfactor</code></em>
            or <em class="parameter"><code>dfactor</code></em> is not an accepted value.
        </p>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated by <code class="function">glBlendFunci</code> if <em class="parameter"><code>buf</code></em> is greater
            than or equal to the value of <code class="constant">GL_MAX_DRAW_BUFFERS</code>.
        </p>
      </div>
      <div class="refsect1" id="associatedgets">
        <h2>Associated Gets</h2>
        <p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_SRC_RGB</code>
        </p>
        <p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_SRC_ALPHA</code>
        </p>
        <p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_DST_RGB</code>
        </p>
        <p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_DST_ALPHA</code>
        </p>
        <p>
            <a class="citerefentry" href="glIsEnabled"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_BLEND</code>
        </p>
        <p>
        </p>
      </div>
      {$pipelinestall}{$examples}
      <div class="refsect1" id="versions">
        <h2>Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">

            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
                <span class="bold"><strong>OpenGL Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function / Feature Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.4</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.5</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                  <code class="function">glBlendFunc</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-bottom: 2px solid ; ">✔</td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                  <code class="function">glBlendFunci</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="glBlendColor"><span class="citerefentry"><span class="refentrytitle">glBlendColor</span></span></a>,
            <a class="citerefentry" href="glBlendEquation"><span class="citerefentry"><span class="refentrytitle">glBlendEquation</span></span></a>,
            <a class="citerefentry" href="glBlendFuncSeparate"><span class="citerefentry"><span class="refentrytitle">glBlendFuncSeparate</span></span></a>,
            <a class="citerefentry" href="glClear"><span class="citerefentry"><span class="refentrytitle">glClear</span></span></a>,
            <a class="citerefentry" href="glDrawBuffer"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>,
            <a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
            <a class="citerefentry" href="glLogicOp"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>,
            <a class="citerefentry" href="glStencilFunc"><span class="citerefentry"><span class="refentrytitle">glStencilFunc</span></span></a>
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright © 1991-2006 Silicon Graphics, Inc.
            Copyright © 2010-2014 Khronos Group.
            This document is licensed under the SGI Free Software B License.
            For details, see
            <a class="link" href="https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/" target="_top">https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/</a>.
        </p>
      </div>
    </div>