unit test numeric failures in test_metal and test_gpu #2211
Description
macOS Sequoia 15.7.1 (i.e. fully up to patch level for Sequoia)
GL Vendor: Apple
GL Renderer: Apple M4 Max
GL Version: 2.1 Metal - 89.4
GLSL Version: 1.20
[202/241] [Lut1DOp / lut1d_file2_disallow_tex1D_test ] - FAILED -
Maximum error: 1 at pixel: 43691 on component 1 larger than epsilon.
src = {1.000015259, 1.000026703, 1.000038147, 1.000049591}
cpu = {0, 1, 0, 1.000049591}
gpu = {0, 0, 0, 1.000049591}
absolute tolerance=9.999999747e-05
If the tolerance is 0.0001, and the failure magnitude is 1.0, this feels like a rounding error in the LUT somewhere.
As an example of a more typical error, as it turns out there are two failures in test_metal, the other being this one:
[ 56/241] [FixedFunction / style_aces2_rgb_to_jmh_fwd ] - FAILED -
Maximum error: 0.000244140625 at pixel: 13 on component 2 larger than epsilon.
src = {0.2668400109, 0.2460400015, 0.4093199968, 1}
cpu = {53.46554947, 13.12156677, 285.6588745, 1}
gpu = {53.4655571, 13.12158012, 285.6591187, 1}
absolute tolerance=0.0001999999949
Over in test_gpu, there's this:
[ 69/241] [FixedFunction / style_RGB_TO_HSV_inv_custom ] - FAILED -
Maximum error: 7.629394531e-06 at pixel: 7 on component 1 larger than epsilon.
src = {0.5, 2.5, 0.03999999911, 0}
cpu = {-39.95812988, 39.9981308, 39.9981308, 0}
gpu = {-39.95812988, 39.99812317, 39.99812317, 0}
absolute tolerance=9.999999975e-07
As I am trying to get ctest to run without failure to satisfy the MacPorts CI system, I'd appreciate insight on the first one here, and would ask if there's a workaround (perhaps a way to relax the tolerances for just one test?) on the second and third ones.