1) Append "Shadow" to samplers representing depth textures.
2) Sampling a depth texture returns f32, not vec4<f32>
3) Sampling a depth texture requires a Dref parameter, so we must
generate one if none is provided.
4) GLSL requires Dref to be appended to the texture coordinates vector,
*unless* it's a samplerCubeArrayShadow, since this would require vec5.
In that case, it's passed as a separate parameter.
5) GLSL's textureGather() with a depth sampler always requires a refZ
parameter, so provide zero to emulate WGSL's compare-less textureGather().
6) texelFetch() does not support depth textures, so this will have to be
validated out.
7) textureOffset() does not support sampler2DArrayShadow in GLES, so this will
have to be validated out.
Bug: tint:1298
Change-Id: Idaebe89cac6c1ec97c50a361b1d3aa3b84fb6c12
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78760
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
d4d7153bad