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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<!-- Converted by db4-upgrade version 1.1 -->
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="textureProjGrad">
<info>
<copyright>
<year>2011-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>textureProjGrad</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>textureProjGrad</refname>
<refpurpose>perform a texture lookup with projection and explicit gradients</refpurpose>
</refnamediv>
<refsynopsisdiv><title>Declaration</title>
<funcsynopsis>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler1D <parameter>sampler</parameter></paramdef>
<paramdef>vec2 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>pDx</parameter></paramdef>
<paramdef>float <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler1D <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>pDx</parameter></paramdef>
<paramdef>float <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler3D <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec3 <parameter>pDx</parameter></paramdef>
<paramdef>vec3 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureProjGrad</function></funcdef>
<paramdef>sampler1DShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>pDx</parameter></paramdef>
<paramdef>float <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureProjGrad</function></funcdef>
<paramdef>sampler2DShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureProjGrad</function></funcdef>
<paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureProjGrad</function></funcdef>
<paramdef>gsampler2DRectShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>pDx</parameter></paramdef>
<paramdef>vec2 <parameter>pDy</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>sampler</parameter></term>
<listitem>
<para>
Specifies the sampler to which the texture from which texels will be retrieved is bound.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>P</parameter></term>
<listitem>
<para>
Specifies the texture coordinates at which texture will be sampled.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dPdx</parameter></term>
<listitem>
<para>
Specifies the partial derivative of <parameter>P</parameter> with respect to window x.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dPdy</parameter></term>
<listitem>
<para>
Specifies the partial derivative of <parameter>P</parameter> with respect to window y.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>textureProjGrad</function> performs a texture lookup with projection and explicit gradients. The texture coordinates
consumed from <parameter>P</parameter>, not including the last component of <parameter>P</parameter>,
are divided by the last component of <parameter>P</parameter>. The resulting <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msup><mml:mn>3</mml:mn><mml:mi>rd</mml:mi></mml:msup></mml:math></inlineequation>
component of <parameter>P</parameter> in the shadow forms is used as
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msub><mml:mi>D</mml:mi><mml:mi>ref</mml:mi></mml:msub></mml:math></inlineequation>.
After these values are computed, the texture lookup proceeds as in <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
passing <parameter>dPdx</parameter> and <parameter>dPdy</parameter> as gradients.
</para>
</refsect1>
<refsect1 xml:id="versions"><title>Version Support</title>
<informaltable>
<tgroup cols="13" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="funchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry>textureProjGrad</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='13']/*)"/>
</row>
<row>
<entry>textureProjGrad (gsampler2DRect{Shadow})</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='14']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 2011-2014 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.
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
</para>
</refsect1>
</refentry>
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