Bug Ambient Occlusion +Texture not working. Apple M1 GPU Rendering #94050

New Issue

Gerrit · 2021-12-14T09:57:15+01:00

Gerrit commented

2021-12-14 09:57:15 +01:00

{F12739017}System Information
Operating system: 'macOS-12.0.1-arm64-arm-64bit'
Graphics card: Apple M1 8 Core GPU '4.1 Metal - 76.1' / 8 Core CPU. 16GB

Blender Version
Broken:
version: 3.1.0 Alpha, branch: master, commit date: 2021-12-14 00:16, hash: c1f5d8d023, type: release
build date: 2021-12-14, 00:59:09

Ambient Occlusion is not working together with texture input. Resulting in black Material (GPU Rendering!)

CPU Rendering is fine.

Exact steps for others to reproduce the error
Switch to GPU Rendering. Add Ambient Occlusion Shader with texture to shader node.

![GPU.png](https://archive.blender.org/developer/F12739018/GPU.png) {[F12739017](https://archive.blender.org/developer/F12739017/CPU.png)}**System Information** Operating system: 'macOS-12.0.1-arm64-arm-64bit' Graphics card: Apple M1 8 Core GPU '4.1 Metal - 76.1' / 8 Core CPU. 16GB **Blender Version** Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-12-14 00:16, hash: c1f5d8d023c6, type: release build date: 2021-12-14, 00:59:09 Ambient Occlusion is not working together with texture input. Resulting in black Material (GPU Rendering!) CPU Rendering is fine. **Exact steps for others to reproduce the error** Switch to GPU Rendering. Add Ambient Occlusion Shader with texture to shader node.

Gerrit commented

2021-12-14 09:57:15 +01:00

Added subscriber: @Khameir

Gerrit changed title from ~~Ambient Occlusion +Texture not working. Apple M1 GPU Rendering~~ to Bug Ambient Occlusion +Texture not working. Apple M1 GPU Rendering

2021-12-14 10:02:39 +01:00

Brecht Van Lommel commented

2021-12-14 16:38:57 +01:00

Added subscribers: @Michael-Jones, @brecht

Brecht Van Lommel commented

2021-12-14 16:38:57 +01:00

CC @michael_jones.

Michael Jones (Apple) commented

2021-12-22 18:20:08 +01:00

I found a workaround after some experimentation:

diff --git a/intern/cycles/kernel/device/gpu/kernel.h b/intern/cycles/kernel/device/gpu/kernel.h
index b50f492e8c7..0c93d3fcf77 100644
--- a/intern/cycles/kernel/device/gpu/kernel.h
+++ b/intern/cycles/kernel/device/gpu/kernel.h
@@ -243,6 +243,10 @@ ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS)
   }
 }
 
+#ifdef __KERNEL_METAL_APPLE__
+constant int __dummy_constant [[function_constant(0)]];
+#endif
+
 ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS)
     ccl_gpu_kernel_signature(integrator_shade_surface_raytrace,
                              ccl_global const int *path_index_array,
@@ -253,7 +257,14 @@ ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS)
 
   if (global_index < work_size) {
     const int state = (path_index_array) ? path_index_array[global_index] : global_index;
-    ccl_gpu_kernel_call(integrator_shade_surface_raytrace(NULL, state, render_buffer));
+
+    KernelGlobals kg = NULL;
+#ifdef __KERNEL_METAL_APPLE__
+    /* T94050: Bug Ambient Occlusion +Texture not working. Apple M1 GPU Rendering */
+    /* Workaround: Dummy offset should not affect result, but somehow fixes bug! */
+    kg +=__dummy_constant;
+#endif
+    ccl_gpu_kernel_call(integrator_shade_surface_raytrace(kg, state, render_buffer));
   }
 }

I found a workaround after some experimentation: ``` diff --git a/intern/cycles/kernel/device/gpu/kernel.h b/intern/cycles/kernel/device/gpu/kernel.h index b50f492e8c7..0c93d3fcf77 100644 --- a/intern/cycles/kernel/device/gpu/kernel.h +++ b/intern/cycles/kernel/device/gpu/kernel.h @@ -243,6 +243,10 @@ ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS) } } +#ifdef __KERNEL_METAL_APPLE__ +constant int __dummy_constant [[function_constant(0)]]; +#endif + ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS) ccl_gpu_kernel_signature(integrator_shade_surface_raytrace, ccl_global const int *path_index_array, @@ -253,7 +257,14 @@ ccl_gpu_kernel(GPU_KERNEL_BLOCK_NUM_THREADS, GPU_KERNEL_MAX_REGISTERS) if (global_index < work_size) { const int state = (path_index_array) ? path_index_array[global_index] : global_index; - ccl_gpu_kernel_call(integrator_shade_surface_raytrace(NULL, state, render_buffer)); + + KernelGlobals kg = NULL; +#ifdef __KERNEL_METAL_APPLE__ + /* T94050: Bug Ambient Occlusion +Texture not working. Apple M1 GPU Rendering */ + /* Workaround: Dummy offset should not affect result, but somehow fixes bug! */ + kg +=__dummy_constant; +#endif + ccl_gpu_kernel_call(integrator_shade_surface_raytrace(kg, state, render_buffer)); } } ```

Michael Jones (Apple) commented

2021-12-22 18:21:38 +01:00

The workaround makes very little sense to me at present, but is being investigated further.