The values of rendered fragments are undefined when a shader stage fetches texels and the same texels are written via fragment shader outputs, even if the reads and writes are not in the same drawing command. To safely read the result of a written texel via a texel fetch in a subsequent drawing command, call glTextureBarrier between the two drawing commands to guarantee that writes have completed and caches have been invalidated before subsequent drawing commands are executed.
The situation described above is referred to as a rendering feedback loop and is discussed in more detail in section 9.3 of the OpenGL 4.5 Specification.
|Function / Feature Name||2.0||2.1||3.0||3.1||3.2||3.3||4.0||4.1||4.2||4.3||4.4||4.5|
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Copyright © 2014 Khronos Group