glCompressedTexSubImage2D

Texturing allows elements of an image array to be read by shaders.

glCompressedTexSubImage2D and glCompressedTextureSubImage2D redefine 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 $\mathit{xoffset}+\mathit{width}-1$ , and the y indices yoffset and $\mathit{yoffset}+\mathit{height}-1$ , 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.

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_ENUM is generated by glCompressedTexSubImage2D if target is GL_TEXTURE_RECTANGLE or GL_PROXY_TEXTURE_RECTANGLE .

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.

GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if texture is not the name of an existing texture object.

GL_INVALID_OPERATION is generated by glCompressedTextureSubImage2D if the effective target is GL_TEXTURE_RECTANGLE .

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.

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

glActiveTexture , glCompressedTexImage1D , glCompressedTexImage2D , glCompressedTexImage3D , glCompressedTexSubImage1D , glCompressedTexSubImage3D , glCopyTexImage1D , glCopyTexImage2D , glCopyTexSubImage1D , glCopyTexSubImage2D , glCopyTexSubImage3D , glPixelStore , glTexImage2D , glTexImage3D , glTexSubImage1D , glTexSubImage2D , glTexSubImage3D , glTexParameter

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