Undefined behaviour in specular_occlusion is visible on Apple M1 #86660

New Issue

Michael · 2021-03-17T12:53:08+01:00

Michael commented

2021-03-17 12:53:08 +01:00

System Information
Operating system: macOS Big Sur
Graphics card: Apple M1

Blender Version
Broken: (example: 2.93alpha, 8936550269, Sun Mar 14 15:10:18 2021 +0100 "EEVEE: Specular Occlusion: Avoid overdarkening on smooth surfaces") until current version
Worked: The versions before

Short description of error
Switching the default defaultcube scene to the matrial view immediately shows the defaultcube in camo pattern of dark shapes.

Exact steps for others to reproduce the error

Use an Apple M1, it is an error that probably doesn't show up on other machines but it is no driver error.
Create new default scene
Switch on material view
Watch camo pattern of dark shapes.
Switch on ambient occlusion
Watch defaultcube in it's usual correct shape.

Long description of error

In the function specular_occlusion (in ambient_occlusion_lib.glsl) visibility_error is defined but not initialized.
occlusion_eval is called and when int(aoSettings) & USE_AO is false (ambient occlusion is off) the function returns leaving
visibility_error undefined.
Back in specular_occlusion "visibility *= mix(safe_rcp(visibility_error), 1.0, roughness);" visibility_error contains now a wide range of undefined values.

Proposed fix (which works for me): Set visibility_error to zero in the early exit case of occlusion_eval:

diff --git a/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl b/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl
index dc5c048422b..9836aa49cd0 100644
--- a/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl
@@ -200,6 +200,7 @@ void occlusion_eval(OcclusionData data,
 {
   if ((int(aoSettings) & USE_AO) == 0) {
     visibility = data.custom_occlusion;
+    visibility_error = 0.0;
     bent_normal = N;
     return;
   }

**System Information** Operating system: macOS Big Sur Graphics card: Apple M1 **Blender Version** Broken: (example: 2.93alpha, 8936550269333297f6c083c92c90f11660b22e33, Sun Mar 14 15:10:18 2021 +0100 "EEVEE: Specular Occlusion: Avoid overdarkening on smooth surfaces") until current version Worked: The versions before **Short description of error** Switching the default defaultcube scene to the matrial view immediately shows the defaultcube in camo pattern of dark shapes. **Exact steps for others to reproduce the error** 1) Use an Apple M1, it is an error that probably doesn't show up on other machines but it is no driver error. 1) Create new default scene 2) Switch on material view 3) Watch camo pattern of dark shapes. 4) Switch on ambient occlusion 5) Watch defaultcube in it's usual correct shape. Long description of error 1) In the function specular_occlusion (in ambient_occlusion_lib.glsl) visibility_error is defined but not initialized. 2) occlusion_eval is called and when int(aoSettings) & USE_AO is false (ambient occlusion is off) the function returns leaving visibility_error undefined. 3) Back in specular_occlusion "visibility *= mix(safe_rcp(visibility_error), 1.0, roughness);" visibility_error contains now a wide range of undefined values. Proposed fix (which works for me): Set visibility_error to zero in the early exit case of occlusion_eval: ``` diff --git a/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl b/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl index dc5c048422b..9836aa49cd0 100644 --- a/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl +++ b/source/blender/draw/engines/eevee/shaders/ambient_occlusion_lib.glsl @@ -200,6 +200,7 @@ void occlusion_eval(OcclusionData data, { if ((int(aoSettings) & USE_AO) == 0) { visibility = data.custom_occlusion; + visibility_error = 0.0; bent_normal = N; return; } ```

Michael commented

2021-03-17 12:53:08 +01:00

Added subscriber: @michael64

Clément Foucault was assigned by Michael

2021-03-17 12:54:44 +01:00

Eitan Traurig commented

2021-03-17 15:51:55 +01:00

Added subscribers: @fclem, @EitanSomething

Clément Foucault was unassigned by Eitan Traurig

2021-03-17 15:51:55 +01:00

Eitan Traurig commented

2021-03-17 15:51:55 +01:00