- void glCompressedTexSubImage1D(GLenum target, GLint level, GLint xoffset, GLsizei width, GLenum format, GLsizei imageSize, const GLvoid * data);
- Specifies the target texture. Must be GL_TEXTURE_1D.
- Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
- Specifies a texel offset in the x direction within the texture array.
- Specifies the width of the texture subimage.
- Specifies the format of the compressed image data stored at address data.
- Specifies the number of unsigned bytes of image data starting at the address specified by data.
- Specifies a pointer to the compressed image data in memory.
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.
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.
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
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