Perform sampling before branching to discard

Browse source

This two fragment shaders that exhibit undefined behavior. In GLSL,
it is undefined to use implicit or explicit derivatives in
non-uniform control flow [1]. The SPIR-V produced by glslang contained
similar undefined behavior, which results in incorrect codegen
with the amdvlk's LLPC shader compiler, and produces visually
incorrect image.

This PR fixes this issue by hoisting the sampling so that it's
executed before discarding. It's a simple fix and may not be
the optimial way to resolve this issue.

[1]
https://www.khronos.org/registry/OpenGL/specs/gl/GLSLangSpec.4.60.pdf
p. 137.

...

This commit is contained in:

Jakub Kuderski 2020-02-13 00:58:44 -05:00 • committed by Jakub Kuderski

parent 3977935d94

commit 8982f8f2ec

4 changed files with 11 additions and 3 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

BIN

data/shaders/parallaxmapping/parallax.frag.spv

View file

Binary file not shown.