upstream-man-pages/man4/glCompressedTexImage2D.xml

   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="glCompressedTexImage2D">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glCompressedTexImage2D</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glCompressedTexImage2D</refname>
  17         <refpurpose>specify a two-dimensional texture image in a compressed format</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glCompressedTexImage2D</function></funcdef>
  23                 <paramdef>GLenum <parameter>target</parameter></paramdef>
  24                 <paramdef>GLint <parameter>level</parameter></paramdef>
  25                 <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
  26                 <paramdef>GLsizei <parameter>width</parameter></paramdef>
  27                 <paramdef>GLsizei <parameter>height</parameter></paramdef>
  28                 <paramdef>GLint <parameter>border</parameter></paramdef>
  29                 <paramdef>GLsizei <parameter>imageSize</parameter></paramdef>
  30                 <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
  31             </funcprototype>
  32         </funcsynopsis>
  33     </refsynopsisdiv>
  34     <!-- eqn: ignoring delim $$ -->
  35     <refsect1 id="parameters"><title>Parameters</title>
  36         <variablelist>
  37         <varlistentry>
  38             <term><parameter>target</parameter></term>
  39             <listitem>
  40                 <para>
  41                     Specifies the target texture.
  42                     Must be <constant>GL_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_2D</constant>,
  43                     <constant>GL_TEXTURE_1D_ARRAY</constant>, <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>,
  44                     <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_X</constant>,
  45                     <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_X</constant>,
  46                     <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_Y</constant>,
  47                     <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</constant>,
  48                     <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_Z</constant>,
  49                     <constant>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</constant>, or
  50                     <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>.
  51                 </para>
  52             </listitem>
  53         </varlistentry>
  54         <varlistentry>
  55             <term><parameter>level</parameter></term>
  56             <listitem>
  57                 <para>
  58                     Specifies the level-of-detail number.
  59                     Level 0 is the base image level.
  60                     Level <emphasis>n</emphasis> is the <emphasis>n</emphasis>th mipmap reduction image.
  61                 </para>
  62             </listitem>
  63         </varlistentry>
  64         <varlistentry>
  65             <term><parameter>internalformat</parameter></term>
  66             <listitem>
  67                 <para>
  68                     Specifies the format of the compressed image data stored at address <parameter>data</parameter>.
  69                 </para>
  70             </listitem>
  71         </varlistentry>
  72         <varlistentry>
  73             <term><parameter>width</parameter></term>
  74             <listitem>
  75                 <para>
  76                     Specifies the width of the texture image.
  77                     All implementations support 2D texture and cube map texture images that are at least 16384 texels wide.
  78                 </para>
  79             </listitem>
  80         </varlistentry>
  81         <varlistentry>
  82             <term><parameter>height</parameter></term>
  83             <listitem>
  84                 <para>
  85                     Specifies the height of the texture image.
  86                     All implementations support 2D texture and cube map texture images that are at least 16384 texels high.
  87                 </para>
  88             </listitem>
  89         </varlistentry>
  90         <varlistentry>
  91             <term><parameter>border</parameter></term>
  92             <listitem>
  93                 <para>
  94                     This value must be 0.
  95                 </para>
  96             </listitem>
  97         </varlistentry>
  98         <varlistentry>
  99             <term><parameter>imageSize</parameter></term>
 100             <listitem>
 101                 <para>
 102                     Specifies the number of unsigned bytes of image data starting at the
 103                     address specified by <parameter>data</parameter>.
 104                 </para>
 105             </listitem>
 106         </varlistentry>
 107         <varlistentry>
 108             <term><parameter>data</parameter></term>
 109             <listitem>
 110                 <para>
 111                     Specifies a pointer to the compressed image data in memory.
 112                 </para>
 113             </listitem>
 114         </varlistentry>
 115         </variablelist>
 116     </refsect1>
 117     <refsect1 id="description"><title>Description</title>
 118         <para>
 119             Texturing allows elements of an image array to be read by shaders.
 120         </para>
 121         <para>
 122             <function>glCompressedTexImage2D</function> loads a previously defined, and retrieved, compressed two-dimensional
 123             texture image if <parameter>target</parameter> is <constant>GL_TEXTURE_2D</constant>, or one of the
 124             cube map faces such as <constant>GL_TEXTURE_CUBE_MAP_POSITIVE_X</constant>.
 125             (see <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>).
 126         </para>
 127         <para>
 128             If <parameter>target</parameter> is <constant>GL_TEXTURE_1D_ARRAY</constant>, <parameter>data</parameter>
 129             is treated as an array of compressed 1D textures.
 130         </para>
 131         <para>
 132             If <parameter>target</parameter> is <constant>GL_PROXY_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>
 133             or <constant>GL_PROXY_CUBE_MAP</constant>, no data is read from <parameter>data</parameter>, but
 134             all of the texture image state is recalculated, checked for consistency,
 135             and checked against the implementation's capabilities.  If the
 136             implementation cannot handle a texture of the requested texture size, it
 137             sets all of the image state to 0, but does not generate an error (see
 138             <citerefentry><refentrytitle>glGetError</refentrytitle></citerefentry>). To query for an entire mipmap array,
 139             use an image array level greater than or equal to 1.
 140         </para>
 141         <para>
 142             <parameter>internalformat</parameter> must be a known compressed image format (such as <constant>GL_RGTC</constant>)
 143             or an extension-specified compressed-texture format.
 144             When a texture is loaded with <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry> using a generic compressed
 145             texture format (e.g., <constant>GL_COMPRESSED_RGB</constant>), the GL selects from one of
 146             its extensions supporting compressed textures.  In order to load the
 147             compressed texture image using <function>glCompressedTexImage2D</function>, query the compressed texture image's
 148             size and format using <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry>.
 149         </para>
 150         <para>
 151             If a non-zero named buffer object is bound to the <constant>GL_PIXEL_UNPACK_BUFFER</constant> target
 152             (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a texture image is
 153             specified, <parameter>data</parameter> is treated as a byte offset into the buffer object's data store.
 154         </para>
 155         <para>
 156             If the compressed data are arranged into fixed-size blocks of texels, the pixel
 157             storage modes can be used to select a sub-rectangle from a larger containing rectangle.
 158             These pixel storage modes operate in the same way as they do for <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>.
 159             In the following description, denote by <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>,
 160             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>,
 161             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math>, and
 162             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math>,
 163             the values of pixel storage modes <constant>GL_UNPACK_COMPRESSED_BLOCK_SIZE</constant>,
 164             <constant>GL_UNPACK_COMPRESSED_BLOCK_WIDTH</constant>, <constant>GL_UNPACK_COMPRESSED_BLOCK_HEIGHT</constant>,
 165             and <constant>GL_UNPACK_COMPRESSED_BLOCK_DEPTH</constant>, respectively.
 166             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math> is
 167             the compressed block size in bytes; <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>,
 168             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math>,
 169             and <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math> are the compressed block width, height, and depth in pixels.
 170         </para>
 171         <para>
 172             By default the pixel storage modes <constant>GL_UNPACK_ROW_LENGTH</constant>,
 173             <constant>GL_UNPACK_SKIP_ROWS</constant>, <constant>GL_UNPACK_SKIP_PIXELS</constant>,
 174             <constant>GL_UNPACK_IMAGE_HEIGHT</constant> and <constant>GL_UNPACK_SKIP_IMAGES</constant>
 175             are ignored for compressed images. To enable <constant>GL_UNPACK_SKIP_PIXELS</constant>
 176             and <constant>GL_UNPACK_ROW_LENGTH</constant>, <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:mrow></mml:math>
 177             and <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math> must both be non-zero.
 178             To also enable <constant>GL_UNPACK_SKIP_ROWS</constant> and <constant>GL_UNPACK_IMAGE_HEIGHT</constant>,
 179             <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:mrow></mml:math> must be non-zero.
 180             To also enable <constant>GL_UNPACK_SKIP_IMAGES</constant>, <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>d</mml:mi></mml:msub></mml:mrow></mml:math>
 181             must be non-zero. All parameters must be consistent with the compressed format to produce the desired results.
 182         </para>
 183         <para>
 184             When selecting a sub-rectangle from a compressed image:
 185             <itemizedlist>
 186                 <listitem>the value of <constant>GL_UNPACK_SKIP_PIXELS</constant> must be a multiple of <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>;</listitem>
 187                 <listitem>the value of <constant>GL_UNPACK_SKIP_ROWS</constant> must be a multiple of <mml:math><mml:mrow><mml:msub><mml:mi>b</mml:mi><mml:mi>w</mml:mi></mml:msub></mml:mrow></mml:math>.</listitem>
 188             </itemizedlist>
 189         </para>
 190         <para>
 191             <parameter>imageSize</parameter> must be equal to:
 192         </para>
 193         <para>
 194 <mml:math display = 'block'>
 195   <mml:mrow>
 196     <mml:msub>
 197       <mml:mi>b</mml:mi>
 198       <mml:mi>s</mml:mi>
 199     </mml:msub>
 200     <mml:mo lspace='2px' rspace='2px'>&times;</mml:mo>
 201     <mml:mfenced open = '&lceil;' close = '&rceil;'>
 202       <mml:mfrac>
 203         <mml:mi>width</mml:mi>
 204         <mml:msub>
 205           <mml:mi>b</mml:mi>
 206           <mml:mi>w</mml:mi>
 207         </mml:msub>
 208       </mml:mfrac>
 209     </mml:mfenced>
 210     <mml:mo lspace='2px' rspace='2px'>&times;</mml:mo>
 211     <mml:mfenced open = '&lceil;' close = '&rceil;'>
 212       <mml:mfrac>
 213         <mml:mi>height</mml:mi>
 214         <mml:msub>
 215           <mml:mi>b</mml:mi>
 216           <mml:mi>h</mml:mi>
 217         </mml:msub>
 218       </mml:mfrac>
 219     </mml:mfenced>
 220   </mml:mrow>
 221 </mml:math>
 222         </para>
 223     </refsect1>
 224     <refsect1 id="notes"><title>Notes</title>
 225         <para>
 226             The specific compressed internal formats <constant>GL_COMPRESSED_RGB8_ETC2</constant>,
 227           <constant>GL_COMPRESSED_SRGB8_ETC2</constant>,
 228           <constant>GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
 229           <constant>GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
 230           <constant>GL_COMPRESSED_RGBA8_ETC2_EAC</constant>,
 231           <constant>GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC</constant>,
 232           <constant>GL_COMPRESSED_R11_EAC</constant>,
 233           <constant>GL_COMPRESSED_SIGNED_R11_EAC</constant>,
 234           <constant>GL_COMPRESSED_RG11_EAC</constant>, and
 235           <constant>GL_COMPRESSED_SIGNED_RG11_EAC</constant> are available only if the GL version
 236           is 4.3 or higher.
 237         </para>
 238     </refsect1>
 239     <refsect1 id="errors"><title>Errors</title>
 240         <para>
 241           <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the specific
 242           compressed internal formats:
 243           <constant>GL_COMPRESSED_RED_RGTC1</constant>,
 244           <constant>GL_COMPRESSED_SIGNED_RED_RGTC1</constant>,
 245           <constant>GL_COMPRESSED_RG_RGTC2</constant>,
 246           <constant>GL_COMPRESSED_SIGNED_RG_RGTC2</constant>.
 247           <constant>GL_COMPRESSED_RGBA_BPTC_UNORM</constant>,
 248           <constant>GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM</constant>,
 249           <constant>GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT</constant>,
 250           <constant>GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT</constant>,
 251           <constant>GL_COMPRESSED_RGB8_ETC2</constant>,
 252           <constant>GL_COMPRESSED_SRGB8_ETC2</constant>,
 253           <constant>GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
 254           <constant>GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2</constant>,
 255           <constant>GL_COMPRESSED_RGBA8_ETC2_EAC</constant>,
 256           <constant>GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC</constant>,
 257           <constant>GL_COMPRESSED_R11_EAC</constant>,
 258           <constant>GL_COMPRESSED_SIGNED_R11_EAC</constant>,
 259           <constant>GL_COMPRESSED_RG11_EAC</constant>, or
 260           <constant>GL_COMPRESSED_SIGNED_RG11_EAC</constant>.
 261         </para>
 262         <para>
 263             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>imageSize</parameter> is not consistent with
 264             the format, dimensions, and contents of the specified compressed image
 265             data.
 266         </para>
 267         <para>
 268             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>border</parameter> is not 0.
 269         </para>
 270         <para>
 271             <constant>GL_INVALID_OPERATION</constant> is generated if parameter combinations are not
 272             supported by the specific compressed internal format as specified in the
 273             specific texture compression extension.
 274         </para>
 275         <para>
 276             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 277             <constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
 278         </para>
 279         <para>
 280             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 281             <constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer
 282             object such that the memory reads required would exceed the data store size.
 283         </para>
 284         <para>
 285             Undefined results, including abnormal program termination, are generated if
 286             <parameter>data</parameter> is not encoded in a manner consistent with the extension
 287             specification defining the internal compression format.
 288         </para>
 289     </refsect1>
 290     <refsect1 id="associatedgets"><title>Associated Gets</title>
 291         <para>
 292             <citerefentry><refentrytitle>glGetCompressedTexImage</refentrytitle></citerefentry>
 293         </para>
 294         <para>
 295             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_COMPRESSED</constant>
 296         </para>
 297         <para>
 298             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
 299         </para>
 300         <para>
 301             <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> with arguments <constant>GL_TEXTURE_INTERNAL_FORMAT</constant>
 302             and <constant>GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant>
 303         </para>
 304     </refsect1>
 305     <refsect1 id="seealso"><title>See Also</title>
 306         <para>
 307             <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
 308             <citerefentry><refentrytitle>glCompressedTexImage1D</refentrytitle></citerefentry>,
 309             <citerefentry><refentrytitle>glCompressedTexImage3D</refentrytitle></citerefentry>,
 310             <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>,
 311             <citerefentry><refentrytitle>glCompressedTexSubImage2D</refentrytitle></citerefentry>,
 312             <citerefentry><refentrytitle>glCompressedTexSubImage3D</refentrytitle></citerefentry>,
 313             <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
 314             <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
 315             <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
 316             <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
 317             <citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry>,
 318             <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
 319             <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
 320             <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
 321             <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
 322             <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>,
 323             <citerefentry><refentrytitle>glTexParameter</refentrytitle></citerefentry>
 324         </para>
 325     </refsect1>
 326     <refsect1 id="Copyright"><title>Copyright</title>
 327         <para>
 328             Copyright <trademark class="copyright"></trademark> 1991-2006
 329             Silicon Graphics, Inc. <trademark class="copyright"></trademark> 2011
 330             Khronos Group. This document is licensed under the SGI
 331             Free Software B License. For details, see
 332             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 333         </para>
 334     </refsect1>
 335 </refentry>