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GLCOMPRESSEDTEXIMAGE(3G)                         OpenGL 3.3                         GLCOMPRESSEDTEXIMAGE(3G)



NAME
       glCompressedTexImage2D - specify a two-dimensional texture image in a compressed format

C SPECIFICATION
       void glCompressedTexImage2D(GLenum target, GLint level, GLenum internalformat, GLsizei width,
                                   GLsizei height, GLint border, GLsizei imageSize, const GLvoid * data);

PARAMETERS
       target
           Specifies the target texture. Must be GL_TEXTURE_2D, GL_PROXY_TEXTURE_2D, GL_TEXTURE_1D_ARRAY,
           GL_PROXY_TEXTURE_1D_ARRAY, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
           GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z,
           GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP.

       level
           Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap
           reduction image.

       internalformat
           Specifies the format of the compressed image data stored at address data.

       width
           Specifies the width of the texture image. All implementations support 2D texture images that are
           at least 64 texels wide and cube-mapped texture images that are at least 16 texels wide.

       height
           Specifies the height of the texture image. All implementations support 2D texture images that are
           at least 64 texels high and cube-mapped texture images that are at least 16 texels high.

       border
           This value must be 0.

       imageSize
           Specifies the number of unsigned bytes of image data starting at the address specified by data.

       data
           Specifies a pointer to the compressed image data in memory.

DESCRIPTION
       Texturing allows elements of an image array to be read by shaders.


       glCompressedTexImage2D loads a previously defined, and retrieved, compressed two-dimensional texture
       image if target is GL_TEXTURE_2D, or one of the cube map faces such as
       GL_TEXTURE_CUBE_MAP_POSITIVE_X. (see glTexImage2D()).

       If target is GL_TEXTURE_1D_ARRAY, data is treated as an array of compressed 1D textures.

       If target is GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_1D_ARRAY or GL_PROXY_CUBE_MAP, no data is read
       from data, but all of the texture image state is recalculated, checked for consistency, and checked
       against the implementation's capabilities. If the implementation cannot handle a texture of the
       requested texture size, it sets all of the image state to 0, but does not generate an error (see
       glGetError()). To query for an entire mipmap array, use an image array level greater than or equal to
       1.


       internalformat must be a known compressed image format (such as GL_RGTC) or an extension-specified
       compressed-texture format. When a texture is loaded with glTexImage2D() using a generic compressed
       texture format (e.g., GL_COMPRESSED_RGB), the GL selects from one of its extensions supporting
       compressed textures. In order to load the compressed texture image using glCompressedTexImage2D,
       query the compressed texture image's size and format using glGetTexLevelParameter().

       If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer())
       while a texture image is specified, data is treated as a byte offset into the buffer object's data
       store.

ERRORS
       GL_INVALID_ENUM is generated if internalformat is not one of the generic compressed internal formats:
       GL_COMPRESSED_RED, GL_COMPRESSED_RG, GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA.  GL_COMPRESSED_SRGB, or
       GL_COMPRESSED_SRGB_ALPHA.


       GL_INVALID_VALUE is generated if imageSize is not consistent with the format, dimensions, and
       contents of the specified compressed image data.


       GL_INVALID_VALUE is generated if border is not 0.


       GL_INVALID_OPERATION is generated if parameter combinations are not supported by the specific
       compressed internal format as specified in the specific texture compression extension.


       GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
       GL_PIXEL_UNPACK_BUFFER target and the buffer object's data store is currently mapped.


       GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
       GL_PIXEL_UNPACK_BUFFER target and the data would be unpacked from the buffer object such that the
       memory reads required would exceed the data store size.

       Undefined results, including abnormal program termination, are generated if data is not encoded in a
       manner consistent with the extension specification defining the internal compression format.

ASSOCIATED GETS
       glGetCompressedTexImage()


       glGet() with argument GL_TEXTURE_COMPRESSED


       glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING


       glGetTexLevelParameter() with arguments GL_TEXTURE_INTERNAL_FORMAT and
       GL_TEXTURE_COMPRESSED_IMAGE_SIZE

SEE ALSO
       glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage3D(), glCompressedTexSubImage1D(),
       glCompressedTexSubImage2D(), glCompressedTexSubImage3D(), glCopyTexImage1D(), glCopyTexSubImage1D(),
       glCopyTexSubImage2D(), glCopyTexSubImage3D(), glPixelStore(), glTexImage2D(), glTexImage3D(),
       glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D(), glTexParameter()


COPYRIGHT
       Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software
       B License. For details, see http://oss.sgi.com/projects/FreeB/.



OpenGL 3.3                                       03/08/2011                         GLCOMPRESSEDTEXIMAGE(3G)