On Thu Apr 27 09:40:48 2023 +0000, Giovanni Mascellani wrote:
Mostly for fun, here is a somewhat more fancy test:
[pixel shader] float4 main(float4 pos : sv_position) : sv_target { pos /= 10.0; float nonlinear = pos.x * pos.y - pos.x * (pos.x + 0.5); return float4(nonlinear, ddx(nonlinear), ddy(nonlinear), 0.0); } [test] draw quad probe (10, 10) rgba (-0.524999976, -0.164999843, 0.104999900, 0.0) 8 probe (11, 10) rgba (-0.689999819, -0.164999843, 0.104999900, 0.0) 8 probe (10, 11) rgba (-0.420000076, -0.164999843, 0.104999900, 0.0) 8 probe (11, 11) rgba (-0.574999928, -0.164999843, 0.104999900, 0.0) 8 probe (12, 10) rgba (-0.874999881, -0.205000162, 0.124999881, 0.0) 8 probe (150, 150) rgba (-7.52500916, -1.56500244, 1.50500488, 0.0) 8An interesting feature is that the partial derivatives are constant across the whole 2x2 tile for all the three drivers I tested (WARP on Windows, RADV on Linux and NVIDIA proprietary on Linux), a non-trivial fact that I would not have given for granted before testing. I also did some tests with trigonometric functions, but NVIDIA's implementation is so wonky that it's nearly impossible to avoid diverging from the other drivers.
Oddly enough this doesn't seem to pass on RADV with a 7900XTX, but just barely:
``` shader_runner:1197: Running tests from a Unix build shader_runner:1199: Compiling shaders with vkd3d-shader and executing with Vulkan shader_runner:601: Section [test], line 19: Test failed: Got {-7.52500343e+00, -1.56500721e+00, 1.50500488e+00, 0.00000000e+00}, expected {-7.52500916e+00, -1.56500244e+00, 1.50500488e+00, 0.00000000e+00} at (150, 150). shader_runner:1202: Compiling shaders with vkd3d-shader and executing with vkd3d shader_runner:612: Driver name: radv, driver info: Mesa 23.2.0-devel. shader_runner:601: Section [test], line 19: Test failed: Got {-7.52500343e+00, -1.56500721e+00, 1.50500488e+00, 0.00000000e+00}, expected {-7.52500916e+00, -1.56500244e+00, 1.50500488e+00, 0.00000000e+00} at (150, 150). shader_runner: 149 tests executed (2 failures, 0 skipped, 0 todo, 0 bugs). FAIL tests/ddxddy.shader_test (exit status: 1) ```