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GLCOMPRESSEDTEXSUBIM(3G)                         OpenGL 3.3                         GLCOMPRESSEDTEXSUBIM(3G)



NAME
       glCompressedTexSubImage2D - specify a two-dimensional texture subimage in a compressed format

C SPECIFICATION
       void glCompressedTexSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset,
                                      GLsizei width, GLsizei height, GLenum format, GLsizei imageSize,
                                      const GLvoid * data);

PARAMETERS
       target
           Specifies the target texture. Must be GL_TEXTURE_2D, 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, or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z.

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

       xoffset
           Specifies a texel offset in the x direction within the texture array.

       yoffset
           Specifies a texel offset in the y direction within the texture array.

       width
           Specifies the width of the texture subimage.

       height
           Specifies the height of the texture subimage.

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

       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.


       glCompressedTexSubImage2D redefines a contiguous subregion of an existing two-dimensional texture
       image. The texels referenced by data replace the portion of the existing texture array with x indices
       xoffset and xoffset + width - 1, and the y indices yoffset and yoffset + height - 1, inclusive. This
       region may not include any texels outside the range of the texture array as it was originally
       specified. It is not an error to specify a subtexture with width of 0, but such a specification has
       no effect.


       internalformat must be a known compressed image format (such as GL_RGTC) or an extension-specified
       compressed-texture format. The format of the compressed texture image is selected by the GL
       implementation that compressed it (see glTexImage2D()) and should be queried at the time the texture
       was compressed with 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 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_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(), glCompressedTexImage2D(), glCompressedTexImage3D(),
       glCompressedTexSubImage1D(), glCompressedTexSubImage3D(), glCopyTexImage1D(), glCopyTexImage2D(),
       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                         GLCOMPRESSEDTEXSUBIM(3G)