[Bf-blender-cvs] [8072ef2ae9f] cycles-x: Fix wrong render with portals and constant background color

[Brecht Van Lommel]

Commit: 8072ef2ae9f0ae4428a34c99f6df28aa32bcfb27
Author: Brecht Van Lommel
Date:   Wed Sep 15 20:30:33 2021 +0200
Branches: cycles-x
https://developer.blender.org/rB8072ef2ae9f0ae4428a34c99f6df28aa32bcfb27

Fix wrong render with portals and constant background color

Need to apply MIS weight also in that case.

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

M	intern/cycles/kernel/integrator/integrator_shade_background.h

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

diff --git a/intern/cycles/kernel/integrator/integrator_shade_background.h b/intern/cycles/kernel/integrator/integrator_shade_background.h
index 3c72251fa2f..3e4cc837e9b 100644
--- a/intern/cycles/kernel/integrator/integrator_shade_background.h
+++ b/intern/cycles/kernel/integrator/integrator_shade_background.h
@@ -41,14 +41,11 @@ ccl_device float3 integrator_eval_background_shader(INTEGRATOR_STATE_ARGS,
       return zero_float3();
   }
 
-  /* Fast path for constant color shader. */
+  /* Use fast constant background color if available. */
   float3 L = zero_float3();
-  if (shader_constant_emission_eval(kg, shader, &L)) {
-    return L;
-  }
+  if (!shader_constant_emission_eval(kg, shader, &L)) {
+    /* Evaluate background shader. */
 
-  /* Evaluate background shader. */
-  {
     /* TODO: does aliasing like this break automatic SoA in CUDA?
      * Should we instead store closures separate from ShaderData? */
     ShaderDataTinyStorage emission_sd_storage;