| 1 | <?xml version="1.0" encoding="UTF-8"?>\r |
| 2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"\r |
| 3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">\r |
| 4 | <refentry id="textureGatherOffset">\r |
| 5 | <refmeta>\r |
| 6 | <refmetainfo>\r |
| 7 | <copyright>\r |
| 8 | <year>2011</year>\r |
| 9 | <holder>Khronos Group</holder>\r |
| 10 | </copyright>\r |
| 11 | </refmetainfo>\r |
| 12 | <refentrytitle>textureGatherOffset</refentrytitle>\r |
| 13 | <manvolnum>3G</manvolnum>\r |
| 14 | </refmeta>\r |
| 15 | <refnamediv>\r |
| 16 | <refname>textureGatherOffset</refname>\r |
| 17 | <refpurpose>gathers four texels from a texture with offset</refpurpose>\r |
| 18 | </refnamediv>\r |
| 19 | <refsynopsisdiv><title>Declaration</title>\r |
| 20 | <funcsynopsis>\r |
| 21 | <funcprototype>\r |
| 22 | <funcdef>gvec4 <function>textureGatherOffset</function></funcdef>\r |
| 23 | <paramdef>gsampler2D <parameter>sampler</parameter></paramdef>\r |
| 24 | <paramdef>vec2 <parameter>P</parameter></paramdef>\r |
| 25 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 26 | <paramdef>[int <parameter>comp]</parameter></paramdef>\r |
| 27 | </funcprototype>\r |
| 28 | <funcprototype>\r |
| 29 | <funcdef>gvec4 <function>textureGatherOffset</function></funcdef>\r |
| 30 | <paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>\r |
| 31 | <paramdef>vec3 <parameter>P</parameter></paramdef>\r |
| 32 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 33 | <paramdef>[int <parameter>comp]</parameter></paramdef>\r |
| 34 | </funcprototype>\r |
| 35 | <funcprototype>\r |
| 36 | <funcdef>gvec4 <function>textureGatherOffset</function></funcdef>\r |
| 37 | <paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>\r |
| 38 | <paramdef>vec3 <parameter>P</parameter></paramdef>\r |
| 39 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 40 | <paramdef>[int <parameter>comp]</parameter></paramdef>\r |
| 41 | </funcprototype>\r |
| 42 | <funcprototype>\r |
| 43 | <funcdef>vec4 <function>textureGatherOffset</function></funcdef>\r |
| 44 | <paramdef>gsampler2DShadow <parameter>sampler</parameter></paramdef>\r |
| 45 | <paramdef>vec2 <parameter>P</parameter></paramdef>\r |
| 46 | <paramdef>float <parameter>refZ</parameter></paramdef>\r |
| 47 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 48 | </funcprototype>\r |
| 49 | <funcprototype>\r |
| 50 | <funcdef>vec4 <function>textureGatherOffset</function></funcdef>\r |
| 51 | <paramdef>gsampler2DArrayShadow <parameter>sampler</parameter></paramdef>\r |
| 52 | <paramdef>vec3 <parameter>P</parameter></paramdef>\r |
| 53 | <paramdef>float <parameter>refZ</parameter></paramdef>\r |
| 54 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 55 | </funcprototype>\r |
| 56 | <funcprototype>\r |
| 57 | <funcdef>vec4 <function>textureGatherOffset</function></funcdef>\r |
| 58 | <paramdef>gsampler2DRectShadow <parameter>sampler</parameter></paramdef>\r |
| 59 | <paramdef>vec3 <parameter>P</parameter></paramdef>\r |
| 60 | <paramdef>float <parameter>refZ</parameter></paramdef>\r |
| 61 | <paramdef>ivec2 <parameter>offset</parameter></paramdef>\r |
| 62 | </funcprototype>\r |
| 63 | </funcsynopsis>\r |
| 64 | </refsynopsisdiv>\r |
| 65 | <refsect1 id="parameters"><title>Parameters</title>\r |
| 66 | <variablelist>\r |
| 67 | <varlistentry>\r |
| 68 | <term><parameter>sampler</parameter></term>\r |
| 69 | <listitem>\r |
| 70 | <para>\r |
| 71 | Specifies the sampler to which the texture from which texels will be retrieved is bound.\r |
| 72 | </para>\r |
| 73 | </listitem>\r |
| 74 | </varlistentry>\r |
| 75 | <varlistentry>\r |
| 76 | <term><parameter>P</parameter></term>\r |
| 77 | <listitem>\r |
| 78 | <para>\r |
| 79 | Specifies the texture coordinates at which texture will be sampled.\r |
| 80 | </para>\r |
| 81 | </listitem>\r |
| 82 | </varlistentry>\r |
| 83 | <varlistentry>\r |
| 84 | <term><parameter>comp</parameter></term>\r |
| 85 | <listitem>\r |
| 86 | <para>\r |
| 87 | Specifies the component of the source texture that will be used to generate the resulting vector.\r |
| 88 | </para>\r |
| 89 | </listitem>\r |
| 90 | </varlistentry>\r |
| 91 | <varlistentry>\r |
| 92 | <term><parameter>refZ</parameter></term>\r |
| 93 | <listitem>\r |
| 94 | <para>\r |
| 95 | Specifies the reference Z value used in the comparison for shadow forms.\r |
| 96 | </para>\r |
| 97 | </listitem>\r |
| 98 | </varlistentry>\r |
| 99 | <varlistentry>\r |
| 100 | <term><parameter>offset</parameter></term>\r |
| 101 | <listitem>\r |
| 102 | <para>\r |
| 103 | Specifies the offset from the specified texture coordinate <parameter>P</parameter> from which the texels will be gathered.\r |
| 104 | </para>\r |
| 105 | </listitem>\r |
| 106 | </varlistentry>\r |
| 107 | </variablelist>\r |
| 108 | </refsect1>\r |
| 109 | <refsect1 id="description"><title>Description</title>\r |
| 110 | <para>\r |
| 111 | <function>textureGatherOffset</function> returns the value:\r |
| 112 | </para>\r |
| 113 | <para>\r |
| 114 | <programlisting><![CDATA[ vec4(Sample_i0_j1(P + offset, base).comp,\r |
| 115 | Sample_i1_j1(P + offset, base).comp,\r |
| 116 | Sample_i1_j0(P + offset, base).comp,\r |
| 117 | Sample_i0_j9(P + offset, base).comp);]]></programlisting>\r |
| 118 | </para>\r |
| 119 | <para>\r |
| 120 | It perfoms as <citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry> but with <parameter>offset</parameter>\r |
| 121 | applied as described in <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>, except that the\r |
| 122 | implementation-dependent minimum and maximum offset values are given by <constant>GL_MIN_PROGRRAM_TEXTURE_GATHER_OFFSET</constant>\r |
| 123 | and <constant>GL_MAX_PROGRAM_TEXTURE_GATHER_OFFSET</constant>, respectively.\r |
| 124 | </para>\r |
| 125 | <para>\r |
| 126 | If specified, the value of <parameter>comp</parameter> must ba constant integer expression with a value\r |
| 127 | of 0, 1, 2, or 3, identifying the x, y, z or w component of the four-component vector lookup result for each\r |
| 128 | texel, respectively. If <parameter>comp</parameter> is not specified, it is treated as 0, selecting the x\r |
| 129 | component of each texel to generate the result.\r |
| 130 | </para>\r |
| 131 | </refsect1>\r |
| 132 | <refsect1 id="versions"><title>Version Support</title>\r |
| 133 | <informaltable frame="topbot">\r |
| 134 | #VARTABLECOLS#\r |
| 135 | <thead>\r |
| 136 | #FUNCTABLEHEADER#\r |
| 137 | <row>\r |
| 138 | <entry>textureGatherOffset</entry>#newin40#\r |
| 139 | </row>\r |
| 140 | </thead>\r |
| 141 | </tgroup>\r |
| 142 | </informaltable>\r |
| 143 | </refsect1>\r |
| 144 | <refsect1 id="seealso"><title>See Also</title>\r |
| 145 | <para>\r |
| 146 | <citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,\r |
| 147 | <citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,\r |
| 148 | <citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,\r |
| 149 | <citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,\r |
| 150 | <citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,\r |
| 151 | <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,\r |
| 152 | <citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,\r |
| 153 | <citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,\r |
| 154 | <citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,\r |
| 155 | <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,\r |
| 156 | <citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,\r |
| 157 | <citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,\r |
| 158 | <citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,\r |
| 159 | <citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,\r |
| 160 | <citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,\r |
| 161 | <citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,\r |
| 162 | <citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,\r |
| 163 | <citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>\r |
| 164 | </para>\r |
| 165 | </refsect1>\r |
| 166 | <refsect1 id="Copyright"><title>Copyright</title>\r |
| 167 | <para>\r |
| 168 | Copyright <trademark class="copyright"></trademark> 2011 Khronos Group. \r |
| 169 | This material may be distributed subject to the terms and conditions set forth in \r |
| 170 | the Open Publication License, v 1.0, 8 June 1999.\r |
| 171 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.\r |
| 172 | </para>\r |
| 173 | </refsect1>\r |
| 174 | </refentry>\r |