Android vulkan validator crashes on depth only (shadow map ) rendering #3486
Description
Describe the bug
I have enabled vulkan validation on android with https://developer.android.com/ndk/guides/graphics/validation-layer.
Our app crashed here with shadowmap rendering shader.
https://github.com/bkaradzic/bgfx/blob/35911ac2d9b651bc0097ea40867f193274d9d960/src/renderer_vk.cpp#L3891C13-L3891C24
Turning off shadowmap rendering fixed the crash. So I checked what is different for this shaders.
I had already seen a strange thing in renderdoc. The shadowmap rendering pass looked like this:
vkCmdBeginRenderPass(C=Unused, D=Clear)
C = Unused looked strange. Why there is a Color buffer?
Line 3377 in 35911ac
It always set color buffer, even when not used.
Commit is here:
870d141
So it was a fix to be able to output color even where there is no color buffer attached.
I have removed this unused colorbuffer. And also removed shader outputs from shaders.
Removed half4 fragColor[[color(0)]]; from metal fragment shader output.
And removed layout(location=0) out vec4 fragColor; from glsl shader output.
It works for metal/gles/vulkan. I don't know if this is possible on d3d11/12, but I think
it would be a cleaner solution to not output color info in shader when there is no color buffer.