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NAME

       glCompressedTexImage1D - specify a one-dimensional texture image in a compressed format

C SPECIFICATION

       void glCompressedTexImage1D(GLenum target, GLint level, GLenum internalformat,
                                   GLsizei width, GLint border, GLsizei imageSize,
                                   const GLvoid * data);

PARAMETERS

       target
           Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.

       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 texture images
           that are at least 64 texels wide. The height of the 1D texture image is 1.

       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.

       glCompressedTexImage1D loads a previously defined, and retrieved, compressed
       one-dimensional texture image if target is GL_TEXTURE_1D (see glTexImage1D()).

       If target is GL_PROXY_TEXTURE_1D, 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 an extension-specified compressed-texture format. When a texture is
       loaded with glTexImage1D() 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 glCompressedTexImage1D,
       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.

       If the compressed data are arranged into fixed-size blocks of texels, the pixel storage
       modes can be used to select a sub-rectangle from a larger containing rectangle. These
       pixel storage modes operate in the same way as they do for glTexImage1D(). In the
       following description, denote by bs, bw, bh, and bd, the values of pixel storage modes
       GL_UNPACK_COMPRESSED_BLOCK_SIZE, GL_UNPACK_COMPRESSED_BLOCK_WIDTH,
       GL_UNPACK_COMPRESSED_BLOCK_HEIGHT, and GL_UNPACK_COMPRESSED_BLOCK_DEPTH, respectively.  bs
       is the compressed block size in bytes; bw, bh, and bd are the compressed block width,
       height, and depth in pixels.

       By default the pixel storage modes GL_UNPACK_ROW_LENGTH, GL_UNPACK_SKIP_ROWS,
       GL_UNPACK_SKIP_PIXELS, GL_UNPACK_IMAGE_HEIGHT and GL_UNPACK_SKIP_IMAGES are ignored for
       compressed images. To enable GL_UNPACK_SKIP_PIXELS and GL_UNPACK_ROW_LENGTH, bs and bw
       must both be non-zero. To also enable GL_UNPACK_SKIP_ROWS and GL_UNPACK_IMAGE_HEIGHT, bh
       must be non-zero. To also enable GL_UNPACK_SKIP_IMAGES, bd must be non-zero. All
       parameters must be consistent with the compressed format to produce the desired results.

       When selecting a sub-rectangle from a compressed image:

       ·   the value of GL_UNPACK_SKIP_PIXELS must be a multiple of bw;.RE

           imageSize must be equal to:

           b s × width b w

ERRORS

       GL_INVALID_ENUM is generated if internalformat is not a supported specific compressed
       internal formats, or is 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_NUM_COMPRESSED_TEXTURE_FORMATS

       glGet() with argument GL_COMPRESSED_TEXTURE_FORMATS

       glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING

       glGetTexLevelParameter() with arguments GL_TEXTURE_INTERNAL_FORMAT and
       GL_TEXTURE_COMPRESSED_IMAGE_SIZE

SEE ALSO

       glActiveTexture(), glCompressedTexImage2D(), glCompressedTexImage3D(),
       glCompressedTexSubImage1D(), glCompressedTexSubImage2D(), glCompressedTexSubImage3D(),
       glCopyTexImage1D(), glCopyTexImage2D(), glCopyTexSubImage1D(), glCopyTexSubImage2D(),
       glCopyTexSubImage3D(), glPixelStore(), glTexImage2D(), glTexImage3D(), glTexSubImage1D(),
       glTexSubImage2D(), glTexSubImage3D(), glTexParameter()

COPYRIGHT

       Copyright © 1991-2006 Silicon Graphics, Inc.  © 2011 Khronos Group. This document is
       licensed under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

AUTHORS

       opengl.org