1 <?xml version=
"1.0" encoding=
"UTF-8"?>
2 <!DOCTYPE book PUBLIC
"-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
3 "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
4 <refentry id=
"textureGather">
9 <holder>Khronos Group
</holder>
12 <refentrytitle>textureGather
</refentrytitle>
13 <manvolnum>3G
</manvolnum>
16 <refname>textureGather
</refname>
17 <refpurpose>gathers four texels from a texture
</refpurpose>
19 <refsynopsisdiv><title>Declaration
</title>
22 <funcdef>gvec4
<function>textureGather
</function></funcdef>
23 <paramdef>gsampler2D
<parameter>sampler
</parameter></paramdef>
24 <paramdef>vec2
<parameter>P
</parameter></paramdef>
25 <paramdef>[int
<parameter>comp]
</parameter></paramdef>
28 <funcdef>gvec4
<function>textureGather
</function></funcdef>
29 <paramdef>gsampler2DArray
<parameter>sampler
</parameter></paramdef>
30 <paramdef>vec3
<parameter>P
</parameter></paramdef>
31 <paramdef>[int
<parameter>comp]
</parameter></paramdef>
34 <funcdef>gvec4
<function>textureGather
</function></funcdef>
35 <paramdef>gsamplerCube
<parameter>sampler
</parameter></paramdef>
36 <paramdef>vec3
<parameter>P
</parameter></paramdef>
37 <paramdef>[int
<parameter>comp]
</parameter></paramdef>
40 <funcdef>gvec4
<function>textureGather
</function></funcdef>
41 <paramdef>gsamplerCubeArray
<parameter>sampler
</parameter></paramdef>
42 <paramdef>vec4
<parameter>P
</parameter></paramdef>
43 <paramdef>[int
<parameter>comp]
</parameter></paramdef>
46 <funcdef>gvec4
<function>textureGather
</function></funcdef>
47 <paramdef>gsampler2DRect
<parameter>sampler
</parameter></paramdef>
48 <paramdef>vec3
<parameter>P
</parameter></paramdef>
49 <paramdef>[int
<parameter>comp]
</parameter></paramdef>
52 <funcdef>vec4
<function>textureGather
</function></funcdef>
53 <paramdef>gsampler2DShadow
<parameter>sampler
</parameter></paramdef>
54 <paramdef>vec2
<parameter>P
</parameter></paramdef>
55 <paramdef>float
<parameter>refZ
</parameter></paramdef>
58 <funcdef>vec4
<function>textureGather
</function></funcdef>
59 <paramdef>gsampler2DArrayShadow
<parameter>sampler
</parameter></paramdef>
60 <paramdef>vec3
<parameter>P
</parameter></paramdef>
61 <paramdef>float
<parameter>refZ
</parameter></paramdef>
64 <funcdef>vec4
<function>textureGather
</function></funcdef>
65 <paramdef>gsamplerCubeShadow
<parameter>sampler
</parameter></paramdef>
66 <paramdef>vec3
<parameter>P
</parameter></paramdef>
67 <paramdef>float
<parameter>refZ
</parameter></paramdef>
70 <funcdef>vec4
<function>textureGather
</function></funcdef>
71 <paramdef>gsamplerCubeArrayShadow
<parameter>sampler
</parameter></paramdef>
72 <paramdef>vec4
<parameter>P
</parameter></paramdef>
73 <paramdef>float
<parameter>refZ
</parameter></paramdef>
76 <funcdef>vec4
<function>textureGather
</function></funcdef>
77 <paramdef>gsampler2DRectShadow
<parameter>sampler
</parameter></paramdef>
78 <paramdef>vec3
<parameter>P
</parameter></paramdef>
79 <paramdef>float
<parameter>refZ
</parameter></paramdef>
83 <refsect1 id=
"parameters"><title>Parameters
</title>
86 <term><parameter>sampler
</parameter></term>
89 Specifies the sampler to which the texture from which texels will be retrieved is bound.
94 <term><parameter>P
</parameter></term>
97 Specifies the texture coordinates at which texture will be sampled.
102 <term><parameter>comp
</parameter></term>
105 Specifies the component of the source texture that will be used to generate the resulting vector.
110 <term><parameter>refZ
</parameter></term>
113 Specifies the reference Z value used in the comparison for shadow forms.
119 <refsect1 id=
"description"><title>Description
</title>
121 <function>textureGather
</function> returns the value:
124 <programlisting><![CDATA[ vec4(Sample_i0_j1(P, base).comp,
125 Sample_i1_j1(P, base).comp,
126 Sample_i1_j0(P, base).comp,
127 Sample_i0_j9(P, base).comp);]]
></programlisting>
130 If specified, the value of
<parameter>comp
</parameter> must ba constant integer expression with a value
131 of
0,
1,
2, or
3, identifying the x, y, z or w component of the four-component vector lookup result for each
132 texel, respectively. If
<parameter>comp
</parameter> is not specified, it is treated as
0, selecting the x
133 component of each texel to generate the result.
136 <refsect1 id=
"versions"><title>Version Support
</title>
137 <informaltable frame=
"topbot">
142 <entry>textureGather
</entry>#newin40#
148 <refsect1 id=
"seealso"><title>See Also
</title>
150 <citerefentry><refentrytitle>texelFetch
</refentrytitle></citerefentry>,
151 <citerefentry><refentrytitle>texelFetchOffset
</refentrytitle></citerefentry>,
152 <citerefentry><refentrytitle>texture
</refentrytitle></citerefentry>,
153 <citerefentry><refentrytitle>textureGatherOffset
</refentrytitle></citerefentry>,
154 <citerefentry><refentrytitle>textureGatherOffsets
</refentrytitle></citerefentry>,
155 <citerefentry><refentrytitle>textureGrad
</refentrytitle></citerefentry>,
156 <citerefentry><refentrytitle>textureGradOffset
</refentrytitle></citerefentry>,
157 <citerefentry><refentrytitle>textureLod
</refentrytitle></citerefentry>,
158 <citerefentry><refentrytitle>textureLodOffset
</refentrytitle></citerefentry>,
159 <citerefentry><refentrytitle>textureOffset
</refentrytitle></citerefentry>,
160 <citerefentry><refentrytitle>textureProj
</refentrytitle></citerefentry>,
161 <citerefentry><refentrytitle>textureProjGrad
</refentrytitle></citerefentry>,
162 <citerefentry><refentrytitle>textureProjGradOffset
</refentrytitle></citerefentry>,
163 <citerefentry><refentrytitle>textureProjLod
</refentrytitle></citerefentry>,
164 <citerefentry><refentrytitle>textureProjLodOffset
</refentrytitle></citerefentry>,
165 <citerefentry><refentrytitle>textureProjOffset
</refentrytitle></citerefentry>,
166 <citerefentry><refentrytitle>textureQueryLod
</refentrytitle></citerefentry>,
167 <citerefentry><refentrytitle>textureSize
</refentrytitle></citerefentry>
170 <refsect1 id=
"Copyright"><title>Copyright
</title>
172 Copyright
<trademark class=
"copyright"></trademark> 2011 Khronos Group.
173 This material may be distributed subject to the terms and conditions set forth in
174 the Open Publication License, v
1.0,
8 June
1999.
175 <ulink url=
"http://opencontent.org/openpub/">http://opencontent.org/openpub/
</ulink>.