Reference glGetTextureSubImage

glGetTextureSubImage: procedure(texture: GLuint; level: GLint; xoffset: GLint; yoffset: GLint; zoffset: GLint; width: GLsizei; height: GLsizei; depth: GLsizei; format: GLenum; type_: GLenum; bufSize: GLsizei; pixels: Pointer); cdecl;