NAME

       glCompressedTexSubImage1D - specify a one-dimensional texture subimage in a compressed
       format

C SPECIFICATION

       void glCompressedTexSubImage1D(GLenum target, GLint level, GLint xoffset, GLsizei width,
                                      GLenum format, GLsizei imageSize, const GLvoid * data);

PARAMETERS

       target
           Specifies the target texture. Must be GL_TEXTURE_1D.

       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.

       width
           Specifies the width 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.

       glCompressedTexSubImage1D redefines a contiguous subregion of an existing one-dimensional
       texture image. The texels referenced by data replace the portion of the existing texture
       array with x indices xoffset and xoffset + width - 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 glTexImage1D()), 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 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_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(), glCompressedTexSubImage2D(), glCompressedTexSubImage3D(),
       glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
       glCopyTexSubImage3D(), glPixelStore(), glTexImage2D(), glTexImage3D(), glTexSubImage1D(),
       glTexSubImage2D(), glTexSubImage3D(), glTexParameter()

COPYRIGHT

       Copyright © 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/.

AUTHORS

       opengl.org