EarlyFragmentTests

[twanks123]

Hello Sascha,
i am working on a rendering engine with vulkan and i have a really silly question :D
So far so good i can render unlimited objects with textures and lighting also works (forward rendering with blending pipelines).
But i need the Depth-Test to be calculated before the fragment shader executes and i dont know how i can specify this in the shader. I dont understand what the Vulkan Documentation means:

An explicit control is provided to allow fragment shaders to enable early fragment tests. If the fragment shader specifies the EarlyFragmentTests OpExecutionMode, the per-fragment tests described in Early Fragment Test Mode are performed prior to fragment shader execution. Otherwise, they are performed after fragment shader execution.

So how i specify "EarlyFragmentTests OpExecutionMode"? Thanks in advance :) (and thanks for your awesome code samples!)

[SaschaWillems]

I haven't yet used early fragment tests in Vulkan, but they should be enabled the same way as with OpenGL (see here).

The "OpExecutionMode" refers to SPIR-V. To enable this, put this in your GLSL shader:

layout(early_fragment_tests) in;

This will enable the SPIR-V exection mode:

P.S. : Can you please use the official Khronos forums for Vulkan or stakoverflow for asking Vulkan related questions instead of the issue tracker? I'm active on both 😉

[twanks123]

okay thanks i didnt know where to ask such questions. :)