SPIRV-Cross/reference/shaders/vulkan/frag/demote-to-helper.vk.nocompat.frag.vk

#version 450
#extension GL_EXT_demote_to_helper_invocation : require

void main()
{
    demote;
    bool _9 = helperInvocationEXT();
    bool helper = _9;
}
Support the SPV_EXT_demote_to_helper_invocation extension. This extension provides a new operation which causes a fragment to be discarded without terminating the fragment shader invocation. The invocation for the discarded fragment becomes a helper invocation, so that derivatives will remain defined. The old `HelperInvocation` builtin becomes undefined when this occurs, so a second new instruction queries the current helper invocation status. This is only fully supported for GLSL. HLSL doesn't support the `IsHelperInvocation` operation and MSL doesn't support the `DemoteToHelperInvocation` op. Fixes #1052. 2019-07-13 20:57:33 +00:00			`#version 450`
			`#extension GL_EXT_demote_to_helper_invocation : require`

			`void main()`
			`{`
			`demote;`
Don't forward uses of an OpIsHelperInvocationEXT op. If this is computed before a `demote`, but used after, forwarding it will produce the wrong value. This does make for uglier shaders, but it's necessary right now to ensure correctness. I needed to use an assembly shader to produce the test for this. `spirv-opt` is not smart enough (or too smart?) to eliminate the variable that would be used in GLSL to express this. 2019-07-18 22:32:35 +00:00			`bool _9 = helperInvocationEXT();`
			`bool helper = _9;`
Support the SPV_EXT_demote_to_helper_invocation extension. This extension provides a new operation which causes a fragment to be discarded without terminating the fragment shader invocation. The invocation for the discarded fragment becomes a helper invocation, so that derivatives will remain defined. The old `HelperInvocation` builtin becomes undefined when this occurs, so a second new instruction queries the current helper invocation status. This is only fully supported for GLSL. HLSL doesn't support the `IsHelperInvocation` operation and MSL doesn't support the `DemoteToHelperInvocation` op. Fixes #1052. 2019-07-13 20:57:33 +00:00			`}`