glgetcompressedteximage(3g) [mojave man page]
GLGETCOMPRESSEDTEXIM(3G) OpenGL 3.3 GLGETCOMPRESSEDTEXIM(3G) NAME
glGetCompressedTexImage - return a compressed texture image C SPECIFICATION
void glGetCompressedTexImage(GLenum target, GLint lod, GLvoid * img); PARAMETERS
target Specifies which texture is to be obtained. GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, 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, and GL_TEXTURE_CUBE_MAP_NEGATIVE_Z are accepted. lod Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level n is the nth mipmap reduction image. img Returns the compressed texture image. DESCRIPTION
glGetCompressedTexImage returns the compressed texture image associated with target and lod into img. img should be an array of GL_TEXTURE_COMPRESSED_IMAGE_SIZE bytes. target specifies whether the desired texture image was one specified by glTexImage1D() (GL_TEXTURE_1D), glTexImage2D() (GL_TEXTURE_2D or any of GL_TEXTURE_CUBE_MAP_*), or glTexImage3D() (GL_TEXTURE_3D). lod specifies the level-of-detail number of the desired image. If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer()) while a texture image is requested, img is treated as a byte offset into the buffer object's data store. To minimize errors, first verify that the texture is compressed by calling glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED. If the texture is compressed, then determine the amount of memory required to store the compressed texture by calling glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED_IMAGE_SIZE. Finally, retrieve the internal format of the texture by calling glGetTexLevelParameter() with argument GL_TEXTURE_INTERNAL_FORMAT. To store the texture for later use, associate the internal format and size with the retrieved texture image. These data can be used by the respective texture or subtexture loading routine used for loading target textures. ERRORS
GL_INVALID_VALUE is generated if lod is less than zero or greater than the maximum number of LODs permitted by the implementation. GL_INVALID_OPERATION is generated if glGetCompressedTexImage is used to retrieve a texture that is in an uncompressed internal format. GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_PACK_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_PACK_BUFFER target and the data would be packed to the buffer object such that the memory writes required would exceed the data store size. ASSOCIATED GETS
glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED_IMAGE_SIZE glGetTexLevelParameter() with argument GL_TEXTURE_INTERNAL_FORMAT glGet() with argument GL_PIXEL_PACK_BUFFER_BINDING SEE ALSO
glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage2D(), glCompressedTexImage3D(), glCompressedTexSubImage1D(), glCompressedTexSubImage2D(), glCompressedTexSubImage3D(), glReadPixels(), glTexImage1D(), glTexImage2D(), glTexImage3D(), glTexParameter(), glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D() 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 GLGETCOMPRESSEDTEXIM(3G)
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GLCOMPRESSEDTEXIMAGE(3G) OpenGL 3.3 GLCOMPRESSEDTEXIMAGE(3G) 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. 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 (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)