skia2/tests/sksl/intrinsics/DFdx.glsl
John Stiles 9078a89b26 Avoid mix-up between MAIN_COORDS and FRAGCOORD.
When compiling test shaders, we were setting SK_FRAGCOORD_BUILTIN on the
`coords` parameter to main() instead of SK_MAIN_COORDS_BUILTIN. These
two built-ins don't have the same type (float2 vs. float4) and don't
mean quite the same thing.

The SPIR-V code generator saw a variable with the SK_FRAGCOORD_BUILTIN
builtin value and assumed the presence of a global variable named
`sk_FragCoord`, which didn't exist (because it was never referenced in
the code, so it was never cloned in from the sksl_frag module).

This is only a concern when compiling test shaders with skslc; real
shaders don't hit these code paths. The generated code here is still
imperfect; if you look closely, you'll see the GLSL and Metal code is
referencing the `coords` variable but it's never declared anywhere.

Change-Id: I3ad249469927ff35eb1e75d6536f95317502708f
Bug: skia:12340
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/440520
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2021-08-18 20:11:19 +00:00

10 lines
459 B
GLSL

out vec4 sk_FragColor;
uniform vec4 testInputs;
uniform vec4 colorGreen;
uniform vec4 colorRed;
vec4 main() {
vec4 expected = vec4(0.0);
return (((((dFdx(testInputs.x) == expected.x && dFdx(testInputs.xy) == expected.xy) && dFdx(testInputs.xyz) == expected.xyz) && dFdx(testInputs) == expected) && sign(dFdx(coords.xx)) == vec2(1.0, 1.0)) && sign(dFdx(coords.yy)) == vec2(0.0, 0.0)) && sign(dFdx(coords)) == vec2(1.0, 0.0) ? colorGreen : colorRed;
}