<div class="refentry"><a id="glGetShaderPrecisionFormat"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetShaderPrecisionFormat — return the range and precision for different shader numeric formats</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glGetShaderPrecisionFormat</strong>(</code></td><td>GLenum <var class="pdparam">shaderType</var>, </td></tr><tr><td> </td><td>GLenum <var class="pdparam">precisionType</var>, </td></tr><tr><td> </td><td>GLint *<var class="pdparam">range</var>, </td></tr><tr><td> </td><td>GLint *<var class="pdparam">precision</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>shaderType</code></em></span></dt><dd><p>Specifies the type of shader to query.

Must be either <code class="constant">GL_VERTEX_SHADER</code>

or <code class="constant">GL_FRAGMENT_SHADER</code>.</p></dd><dt><span class="term"><em class="parameter"><code>precisionType</code></em></span></dt><dd><p>Specifies the numeric format to query, corresponding to a shader precision qualifier and variable type.

Must be one of <code class="constant">GL_LOW_FLOAT</code>, <code class="constant">GL_MEDIUM_FLOAT</code>,

<code class="constant">GL_HIGH_FLOAT</code>, <code class="constant">GL_LOW_INT</code>,

<code class="constant">GL_MEDIUM_INT</code>, or <code class="constant">GL_HIGH_INT</code>.</p></dd><dt><span class="term"><em class="parameter"><code>range</code></em></span></dt><dd><p>Specifies a pointer to the two-element array in which the

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<mrow>

<msub><mi mathvariant="italic">log</mi>

<mn>2</mn>

</msub>

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of the minimum and maximum representable magnitudes of the format

are returned.</p></dd><dt><span class="term"><em class="parameter"><code>precision</code></em></span></dt><dd><p>Specifies a pointer to the location in which the

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<mrow>

<msub><mi mathvariant="italic">log</mi>

<mn>2</mn>

</msub>

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of the precision of the format is returned.</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p><code class="function">glGetShaderPrecisionFormat</code>

returns range and precision limits for floating-point and integer shader variable formats with low,

medium, and high precision qualifiers.

When <math overflow="scroll"><mi mathvariant="italic">minRep</mi></math>

and <math overflow="scroll"><mi mathvariant="italic">maxRep</mi></math>

are the minimum and maximum representable values of the format,

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<mrow>

<mi mathvariant="italic">floor</mi>

<mo>⁡</mo>

<mfenced open="(" close=")">

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<mn>2</mn>

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<mi mathvariant="italic">minRep</mi>

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and

<math overflow="scroll">

<mrow>

<mi mathvariant="italic">floor</mi>

<mo>⁡</mo>

<mfenced open="(" close=")">

<mrow>

<msub><mi mathvariant="italic">log</mi>

<mn>2</mn>

</msub>

<mo>⁡</mo>

<mfenced open="(" close=")">

<mrow>

<mfenced open="|" close="|">

<mrow>

<mi mathvariant="italic">maxRep</mi>

</mrow>

</mfenced>

</mrow>

</mfenced>

</mrow>

</mfenced>

</mrow>

</math>

are returned in

<em class="parameter"><code>range</code></em> as the first and second elements, respectively.</p><p>If the smallest representable value greater than 1 is

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<mfenced open="(" close=")">

<mrow>

<mn>1</mn>

<mo>+</mo>

<mn>∊</mn>

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then

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<mrow>

<mi mathvariant="italic">floor</mi>

<mo>⁡</mo>

<mfenced open="(" close=")">

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<mo>-</mo>

<msub><mi mathvariant="italic">log</mi>

<mn>2</mn>

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<mn>∊</mn>

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is returned in <em class="parameter"><code>precision</code></em>.

An integer format will have an ∊ of 1, and thus will return 0.

Floating-point formats will return values greater than 0.</p></div><div class="refsect1"><a id="notes"></a><h2>Notes</h2><p>The minimum range and precision required for different formats is

described in the <span class="emphasis"><em>OpenGL ES Shading Language Specification.</em></span></p><p>If a high precision floating-point format is not supported for fragment shaders,

calling <code class="function">glGetShaderPrecisionFormat</code> with arguments <code class="constant">GL_FRAGMENT_SHADER</code>

and <code class="constant">GL_HIGH_FLOAT</code> will return 0 for both <em class="parameter"><code>range</code></em> and

<em class="parameter"><code>precision</code></em>. Support for a high precision floating-point format is mandatory for

vertex shaders.</p><p>Shader compiler support is optional, and thus must be queried

before use by calling <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>

with argument <code class="constant">GL_SHADER_COMPILER</code>. <a class="citerefentry" href="glShaderSource"><span class="citerefentry"><span class="refentrytitle">glShaderSource</span></span></a>,

<a class="citerefentry" href="glCompileShader"><span class="citerefentry"><span class="refentrytitle">glCompileShader</span></span></a>, <code class="function">glGetShaderPrecisionFormat</code>, and

<a class="citerefentry" href="glReleaseShaderCompiler"><span class="citerefentry"><span class="refentrytitle">glReleaseShaderCompiler</span></span></a> will

each generate <code class="constant">GL_INVALID_OPERATION</code> on implementations

that do not support a shader compiler. Such implementations instead offer the

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

alternative for supplying a pre-compiled shader binary.</p><p>If an error is generated, no change is made to the

contents of <em class="parameter"><code>range</code></em> or <em class="parameter"><code>precision</code></em>.</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_OPERATION</code> is generated if

a shader compiler is not supported.</p><p><code class="constant">GL_INVALID_ENUM</code> is generated if

<em class="parameter"><code>shaderType</code></em> or <em class="parameter"><code>precisionType</code></em> is not

an accepted value.</p></div><div class="refsect1"><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_SHADER_COMPILER</code></p></div>

{$pipelinestall}{$examples}

<div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p><a class="citerefentry" href="glCompileShader"><span class="citerefentry"><span class="refentrytitle">glCompileShader</span></span></a>,

<a class="citerefentry" href="glShaderSource"><span class="citerefentry"><span class="refentrytitle">glShaderSource</span></span></a></p></div><div class="refsect1"><div id="Copyright"><h2>Copyright</h2><p>

Copyright © 2008 Khronos Group.

This material may be distributed subject to the terms and conditions set forth in

the Open Publication License, v 1.0, 8 June 1999.

<a class="ulink" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.

</p></div></div></div>