upstream-doc/manglsl/xhtml/textureGrad.xml

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   4 <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>textureGrad - OpenGL Shading Language (GLSL)</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="textureGrad"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>textureGrad — perform a texture lookup with explicit gradients</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler1D  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler2D  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler3D  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsamplerCube  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler2DRect  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">float <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler2DRectShadow  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">float <b class="fsfunc">textureGrad</b>(</code></td><td>sampler1DShadow  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">float <b class="fsfunc">textureGrad</b>(</code></td><td>sampler2DShadow  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler1DArray  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsampler2DArray  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec2  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr><td><code class="funcdef">float <b class="fsfunc">textureGrad</b>(</code></td><td>sampler1DArrayShadow  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>float  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">gvec4 <b class="fsfunc">textureGrad</b>(</code></td><td>gsamplerCubeArray  </td><td><var class="pdparam">sampler</var>, </td></tr><tr><td> </td><td>vec4  </td><td><var class="pdparam">P</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdx</var>, </td></tr><tr><td> </td><td>vec3  </td><td><var class="pdparam">dPdy</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>sampler</code></em></span></dt><dd><p>
   5                     Specifies the sampler to which the texture from which texels will be retrieved is bound.
   6                 </p></dd><dt><span class="term"><em class="parameter"><code>P</code></em></span></dt><dd><p>
   7                     Specifies the texture coordinates at which texture will be sampled.
   8                 </p></dd><dt><span class="term"><em class="parameter"><code>dPdx</code></em></span></dt><dd><p>
   9                     Specifies the partial derivative of <em class="parameter"><code>P</code></em> with respect to window x.
  10                 </p></dd><dt><span class="term"><em class="parameter"><code>dPdy</code></em></span></dt><dd><p>
  11                     Specifies the partial derivative of <em class="parameter"><code>P</code></em> with respect to window y.
  12                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  13             <code class="function">textureGrad</code> performs a texture lookup at coordinate <em class="parameter"><code>P</code></em> from the
  14             texture bound to <em class="parameter"><code>sampler</code></em> with explicit texture coordinate gradiends as specified in
  15             <em class="parameter"><code>dPdx</code></em> and <em class="parameter"><code>dPdy</code></em>. Set:
  16         </p><p>
  17             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  18                 <mml:mfrac>
  19                   <mml:mi>δs</mml:mi>
  20                   <mml:mi>δx</mml:mi>
  21                 </mml:mfrac>
  22                 <mml:mo>=</mml:mo>
  23                 <mml:mfrac>
  24                   <mml:mi>δP</mml:mi>
  25                   <mml:mi>δx</mml:mi>
  26                 </mml:mfrac>
  27                 <mml:mi>  for a 1D texture,   </mml:mi>
  28                 <mml:mfrac>
  29                   <mml:mi>δP.s</mml:mi>
  30                   <mml:mi>δx</mml:mi>
  31                 </mml:mfrac>
  32                 <mml:mi>   otherwise</mml:mi>
  33             </mml:math>
  34         </p><p>
  35             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  36                 <mml:mfrac>
  37                   <mml:mi>δs</mml:mi>
  38                   <mml:mi>δy</mml:mi>
  39                 </mml:mfrac>
  40                 <mml:mo>=</mml:mo>
  41                 <mml:mfrac>
  42                   <mml:mi>δP</mml:mi>
  43                   <mml:mi>δy</mml:mi>
  44                 </mml:mfrac>
  45                 <mml:mi>   for a 1D texture,  </mml:mi>
  46                 <mml:mfrac>
  47                   <mml:mi>δP.s</mml:mi>
  48                   <mml:mi>δy</mml:mi>
  49                 </mml:mfrac>
  50                 <mml:mi>   otherwise</mml:mi>
  51             </mml:math>
  52         </p><p>
  53             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  54                 <mml:mfrac>
  55                   <mml:mi>δt</mml:mi>
  56                   <mml:mi>δx</mml:mi>
  57                 </mml:mfrac>
  58                 <mml:mo>=</mml:mo>
  59                 <mml:mn>0.0</mml:mn>
  60                 <mml:mi>  for a 1D texture,  </mml:mi>
  61                 <mml:mfrac>
  62                   <mml:mi>δP.t</mml:mi>
  63                   <mml:mi>δx</mml:mi>
  64                 </mml:mfrac>
  65                 <mml:mi> otherwise</mml:mi>
  66             </mml:math>
  67         </p><p>
  68             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  69                 <mml:mfrac>
  70                   <mml:mi>δt</mml:mi>
  71                   <mml:mi>δy</mml:mi>
  72                 </mml:mfrac>
  73                 <mml:mo>=</mml:mo>
  74                 <mml:mn>0.0</mml:mn>
  75                 <mml:mi>  for a 1D texture,  </mml:mi>
  76                 <mml:mfrac>
  77                   <mml:mi>δP.t</mml:mi>
  78                   <mml:mi>δy</mml:mi>
  79                 </mml:mfrac>
  80                 <mml:mi>  otherwise</mml:mi>
  81             </mml:math>
  82         </p><p>
  83             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  84                 <mml:mfrac>
  85                   <mml:mi>δr</mml:mi>
  86                   <mml:mi>δx</mml:mi>
  87                 </mml:mfrac>
  88                 <mml:mo>=</mml:mo>
  89                 <mml:mn>0.0</mml:mn>
  90                 <mml:mi>  for a 1D or 2D texture,  </mml:mi>
  91                 <mml:mfrac>
  92                   <mml:mi>δP.p</mml:mi>
  93                   <mml:mi>δx</mml:mi>
  94                 </mml:mfrac>
  95                 <mml:mi>  otherwise</mml:mi>
  96             </mml:math>
  97         </p><p>
  98             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  99                 <mml:mfrac>
 100                   <mml:mi>δr</mml:mi>
 101                   <mml:mi>δy</mml:mi>
 102                 </mml:mfrac>
 103                 <mml:mo>=</mml:mo>
 104                 <mml:mn>0.0</mml:mn>
 105                 <mml:mi>  for a 1D or 2D texture,  </mml:mi>
 106                 <mml:mfrac>
 107                   <mml:mi>δP.p</mml:mi>
 108                   <mml:mi>δy</mml:mi>
 109                 </mml:mfrac>
 110                 <mml:mi>  otherwise</mml:mi>
 111             </mml:math>
 112         </p><p>
 113             For the cube version, the partial derivatives of <em class="parameter"><code>P</code></em> are assumed to be
 114             in the coordinate system used before texture coordinates are projected onto the appropriate
 115             cube face.
 116         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="versions"></a><h2>Version Support</h2><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>Function</strong></span></th><th align="left"><span class="bold"><strong>Version 1.10</strong></span></th><th align="left"><span class="bold"><strong>Version 1.20</strong></span></th><th align="left"><span class="bold"><strong>Version 1.30</strong></span></th><th align="left"><span class="bold"><strong>Version 1.40</strong></span></th><th align="left"><span class="bold"><strong>Version 1.50</strong></span></th><th align="left"><span class="bold"><strong>Version 3.30</strong></span></th><th align="left"><span class="bold"><strong>Version 4.00</strong></span></th><th align="left"><span class="bold"><strong>Version 4.10</strong></span></th><th align="left"><span class="bold"><strong>Version 4.20</strong></span></th><th align="center"><span class="bold"><strong>Version 4.30</strong></span></th></tr><tr><th align="left">textureGrad</th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr><tr><th align="left">textureGrad (gsampler2DRect{Shadow})</th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr><tr><th align="left">textureGrad (gsamplerCubeArray)</th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr></thead></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 117             <a href="texelFetch.xml"><span class="citerefentry"><span class="refentrytitle">texelFetch</span></span></a>,
 118             <a href="texelFetchOffset.xml"><span class="citerefentry"><span class="refentrytitle">texelFetchOffset</span></span></a>,
 119             <a href="texture.xml"><span class="citerefentry"><span class="refentrytitle">texture</span></span></a>,
 120             <a href="textureGather.xml"><span class="citerefentry"><span class="refentrytitle">textureGather</span></span></a>,
 121             <a href="textureGatherOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureGatherOffset</span></span></a>,
 122             <a href="textureGatherOffsets.xml"><span class="citerefentry"><span class="refentrytitle">textureGatherOffsets</span></span></a>,
 123             <a href="textureGradOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureGradOffset</span></span></a>,
 124             <a href="textureLod.xml"><span class="citerefentry"><span class="refentrytitle">textureLod</span></span></a>,
 125             <a href="textureLodOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureLodOffset</span></span></a>,
 126             <a href="textureOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureOffset</span></span></a>,
 127             <a href="textureProj.xml"><span class="citerefentry"><span class="refentrytitle">textureProj</span></span></a>,
 128             <a href="textureProjGrad.xml"><span class="citerefentry"><span class="refentrytitle">textureProjGrad</span></span></a>,
 129             <a href="textureProjGradOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureProjGradOffset</span></span></a>,
 130             <a href="textureProjLod.xml"><span class="citerefentry"><span class="refentrytitle">textureProjLod</span></span></a>,
 131             <a href="textureProjLodOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureProjLodOffset</span></span></a>,
 132             <a href="textureProjOffset.xml"><span class="citerefentry"><span class="refentrytitle">textureProjOffset</span></span></a>,
 133             <a href="textureQueryLod.xml"><span class="citerefentry"><span class="refentrytitle">textureQueryLod</span></span></a>,
 134             <a href="textureSize.xml"><span class="citerefentry"><span class="refentrytitle">textureSize</span></span></a>
 135         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 136             Copyright <span class="trademark"></span>© 2011 Khronos Group.
 137             This material may be distributed subject to the terms and conditions set forth in
 138             the Open Publication License, v 1.0, 8 June 1999.
 139             <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
 140         </p></div></div></body></html>