[Bf-blender-cvs] [c56cf50bd0b] blender-v3.0-release: Fix T92876: Cycles incorrect volume emission + absorption handling

[Brecht Van Lommel]

Commit: c56cf50bd0b68ccbdba17fe715278f08a9cef7e9
Author: Brecht Van Lommel
Date:   Tue Nov 9 13:04:37 2021 +0100
Branches: blender-v3.0-release
https://developer.blender.org/rBc56cf50bd0b68ccbdba17fe715278f08a9cef7e9

Fix T92876: Cycles incorrect volume emission + absorption handling

===================================================================

M	intern/cycles/kernel/film/accumulate.h
M	intern/cycles/kernel/integrator/shade_background.h
M	intern/cycles/kernel/integrator/shade_light.h
M	intern/cycles/kernel/integrator/shade_surface.h
M	intern/cycles/kernel/integrator/shade_volume.h

===================================================================

diff --git a/intern/cycles/kernel/film/accumulate.h b/intern/cycles/kernel/film/accumulate.h
index 30e1afea751..33f913a6746 100644
--- a/intern/cycles/kernel/film/accumulate.h
+++ b/intern/cycles/kernel/film/accumulate.h
@@ -540,11 +540,10 @@ ccl_device_inline void kernel_accum_background(KernelGlobals kg,
 /* Write emission to render buffer. */
 ccl_device_inline void kernel_accum_emission(KernelGlobals kg,
                                              ConstIntegratorState state,
-                                             const float3 throughput,
                                              const float3 L,
                                              ccl_global float *ccl_restrict render_buffer)
 {
-  float3 contribution = throughput * L;
+  float3 contribution = L;
   kernel_accum_clamp(kg, &contribution, INTEGRATOR_STATE(state, path, bounce) - 1);
 
   ccl_global float *buffer = kernel_accum_pixel_render_buffer(kg, state, render_buffer);
diff --git a/intern/cycles/kernel/integrator/shade_background.h b/intern/cycles/kernel/integrator/shade_background.h
index 24482e85b05..31452de1ca4 100644
--- a/intern/cycles/kernel/integrator/shade_background.h
+++ b/intern/cycles/kernel/integrator/shade_background.h
@@ -175,7 +175,7 @@ ccl_device_inline void integrate_distant_lights(KernelGlobals kg,
 
       /* Write to render buffer. */
       const float3 throughput = INTEGRATOR_STATE(state, path, throughput);
-      kernel_accum_emission(kg, state, throughput, light_eval, render_buffer);
+      kernel_accum_emission(kg, state, throughput * light_eval, render_buffer);
     }
   }
 }
diff --git a/intern/cycles/kernel/integrator/shade_light.h b/intern/cycles/kernel/integrator/shade_light.h
index 7dad3b4e49d..5abe9e98abc 100644
--- a/intern/cycles/kernel/integrator/shade_light.h
+++ b/intern/cycles/kernel/integrator/shade_light.h
@@ -90,7 +90,7 @@ ccl_device_inline void integrate_light(KernelGlobals kg,
 
   /* Write to render buffer. */
   const float3 throughput = INTEGRATOR_STATE(state, path, throughput);
-  kernel_accum_emission(kg, state, throughput, light_eval, render_buffer);
+  kernel_accum_emission(kg, state, throughput * light_eval, render_buffer);
 }
 
 ccl_device void integrator_shade_light(KernelGlobals kg,
diff --git a/intern/cycles/kernel/integrator/shade_surface.h b/intern/cycles/kernel/integrator/shade_surface.h
index d9006e71ce0..e6fe5a87120 100644
--- a/intern/cycles/kernel/integrator/shade_surface.h
+++ b/intern/cycles/kernel/integrator/shade_surface.h
@@ -101,7 +101,7 @@ ccl_device_forceinline void integrate_surface_emission(KernelGlobals kg,
   }
 
   const float3 throughput = INTEGRATOR_STATE(state, path, throughput);
-  kernel_accum_emission(kg, state, throughput, L, render_buffer);
+  kernel_accum_emission(kg, state, throughput * L, render_buffer);
 }
 #endif /* __EMISSION__ */
 
diff --git a/intern/cycles/kernel/integrator/shade_volume.h b/intern/cycles/kernel/integrator/shade_volume.h
index 412be289ebe..86d712cdf32 100644
--- a/intern/cycles/kernel/integrator/shade_volume.h
+++ b/intern/cycles/kernel/integrator/shade_volume.h
@@ -608,7 +608,7 @@ ccl_device_forceinline void volume_integrate_heterogeneous(
         if (!result.indirect_scatter) {
           const float3 emission = volume_emission_integrate(
               &coeff, closure_flag, transmittance, dt);
-          accum_emission += emission;
+          accum_emission += result.indirect_throughput * emission;
         }
       }
 
@@ -661,7 +661,7 @@ ccl_device_forceinline void volume_integrate_heterogeneous(
 
   /* Write accumulated emission. */
   if (!is_zero(accum_emission)) {
-    kernel_accum_emission(kg, state, result.indirect_throughput, accum_emission, render_buffer);
+    kernel_accum_emission(kg, state, accum_emission, render_buffer);
   }
 
 #  ifdef __DENOISING_FEATURES__