glGetCompressedTexImage

glGetCompressedTexImage and glGetnCompressedTexImage return the compressed texture image associated with target and lod into pixels . glGetCompressedTextureImage serves the same purpose, but instead of taking a texture target, it takes the ID of the texture object. pixels should be an array of bufSize bytes for glGetnCompresedTexImage and glGetCompressedTextureImage functions, and of GL_TEXTURE_COMPRESSED_IMAGE_SIZE bytes in case of glGetCompressedTexImage . If the actual data takes less space than bufSize , the remaining bytes will not be touched. target specifies the texture target, to which the texture the data the function should extract the data from is bound to. 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, pixels 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, you can 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.

GL_INVALID_OPERATION is generated by glGetCompressedTextureImage if texture is not the name of an existing texture object.

GL_INVALID_VALUE is generated if level is less than zero or greater than the maximum number of LODs permitted by the implementation.

GL_INVALID_OPERATION is generated if glGetCompressedTexImage , glGetnCompressedTexImage , and glGetCompressedTextureImage 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, the buffer storage was not initialized with glBufferStorage using GL_MAP_PERSISTENT_BIT flag, 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.

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

glActiveTexture , glCompressedTexImage1D , glCompressedTexImage2D , glCompressedTexImage3D , glCompressedTexSubImage1D , glCompressedTexSubImage2D , glCompressedTexSubImage3D , glReadPixels , glTexImage1D , glTexImage2D , glTexImage3D , glTexParameter , glTexSubImage1D , glTexSubImage2D , glTexSubImage3D

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