<div class="refentry" title="glPointSize"><a id="glPointSize"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPointSize — specify the diameter of rasterized points</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glPointSize</b>(</code></td><td>GLfloat <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glPointSizex</b>(</code></td><td>GLfixed <var class="pdparam">size</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term">

<em class="parameter"><code>size</code></em>

</span></dt><dd><p>Specifies the diameter of rasterized points. The

initial value is 1.</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p><code class="function">glPointSize</code>

specifies the rasterized diameter of both aliased and

antialiased points. Using a point size other than 1 has

different effects, depending on whether point antialiasing is

enabled. To enable and disable point antialiasing, call

<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_POINT_SMOOTH</code>.

Point antialiasing is initially disabled.</p><p>If point antialiasing is disabled, the actual size is

determined by rounding the supplied size to the nearest

integer. (If the rounding results in the value 0, it is as if

the point size were 1.) If the rounded size is odd, then the

center point

<math overflow="scroll">

<mfenced><mi>x</mi><mi>y</mi></mfenced>

</math>

of the pixel fragment that represents the point is computed

as</p><div class="informalequation"><math overflow="scroll">

<mfenced>

<mrow>

<mo>[</mo>

<msub><mi>x</mi><mi>w</mi></msub>

<mo>]</mo>

<mo>+</mo>

<mfrac><mn>1</mn><mn>2</mn></mfrac>

</mrow>

<mrow>

<mo>[</mo>

<msub><mi>y</mi><mi>w</mi></msub>

<mo>]</mo>

<mo>+</mo>

<mfrac><mn>1</mn><mn>2</mn></mfrac>

</mrow>

</mfenced>

</math></div><p>where <em class="replaceable"><code>w</code></em>

subscripts indicate window coordinates. All pixels that lie

within the square grid of the rounded size centered at

<math overflow="scroll">

<mfenced><mi>x</mi><mi>y</mi></mfenced>

</math>

make up the fragment. If the size is even, the center point

is</p><div class="informalequation"><math overflow="scroll">

<mfenced>

<mrow>

<mo>[</mo>

<msub><mi>x</mi><mi>w</mi></msub>

<mo>+</mo>

<mfrac><mn>1</mn><mn>2</mn></mfrac>

<mo>]</mo>

</mrow>

<mrow>

<mo>[</mo>

<msub><mi>y</mi><mi>w</mi></msub>

<mo>+</mo>

<mfrac><mn>1</mn><mn>2</mn></mfrac>

<mo>]</mo>

</mrow>

</mfenced>

</math></div><p>and the rasterized fragment's centers are the

half-integer window coordinates within the square of the

rounded size centered at

<math overflow="scroll">

<mfenced><mi>x</mi><mi>y</mi></mfenced>

</math>.

All pixel fragments produced in rasterizing a nonantialiased

point are assigned the same associated data, that of the vertex

corresponding to the point.</p><p>If antialiasing is enabled, then point rasterization

produces a fragment for each pixel square that intersects the

region lying within the circle having diameter equal to the

current point size and centered at the point's

<math overflow="scroll">

<mfenced>

<msub><mi>x</mi><mi>w</mi></msub>

<msub><mi>y</mi><mi>w</mi></msub>

</mfenced>

</math>.

The coverage value for each fragment is the window

coordinate area of the intersection of the circular region with

the corresponding pixel square. This value is saved and used in

the final rasterization step. The data associated with each

fragment is the data associated with the point being

rasterized.</p><p>Not all sizes are supported when point antialiasing is

enabled. If an unsupported size is requested, the nearest

supported size is used. Only size 1 is guaranteed to be

supported; others depend on the implementation. To query the

range of supported sizes, call

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>

with the argument

<code class="constant">GL_SMOOTH_POINT_SIZE_RANGE</code>.

For aliased points, query the supported ranges

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>

with the argument

<code class="constant">GL_ALIASED_POINT_SIZE_RANGE</code>.</p></div><div class="refsect1" title="Notes"><a id="notes"></a><h2>Notes</h2><p>A non-antialiased point size may be clamped to an

implementation-dependent maximum. Although this maximum cannot

be queried, it must be no less than the maximum value for

antialiased points, rounded to the nearest integer

value.</p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p>

<code class="constant">GL_INVALID_VALUE</code> is generated if

<em class="parameter"><code>size</code></em> is less than or equal to 0.</p></div><div class="refsect1" title="Associated Gets"><a id="associatedgets"></a><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_ALIASED_POINT_SIZE_RANGE</code></p><p>

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>

with argument <code class="constant">GL_SMOOTH_POINT_SIZE_RANGE</code></p></div><div class="refsect1" title="See Also"><a id="seealso"></a><h2>See Also</h2><p>

<a class="citerefentry" href="glEnable"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>

</p></div><div class="refsect1" title="Copyright"><a id="copyright"></a><h2>Copyright</h2><p>

Copyright © 2003-2004

Silicon Graphics, Inc. This document is licensed under the SGI

Free Software B License. For details, see

<a class="ulink" 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>