[Bf-blender-cvs] [981d7381cd2] master: Fix T77069 EEVEE: Mix shader with holdout & transparent BSDF fails

[Clément Foucault]

Commit: 981d7381cd27432616c69d63cfaeb16aff6d3edb
Author: Clément Foucault
Date:   Tue Jun 30 21:12:32 2020 +0200
Branches: master
https://developer.blender.org/rB981d7381cd27432616c69d63cfaeb16aff6d3edb

Fix T77069 EEVEE: Mix shader with holdout & transparent BSDF fails

This follows Cycles closer.

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

M	source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl

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

diff --git a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
index 402d306df45..393ecaf1fc5 100644
--- a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
@@ -877,6 +877,14 @@ Closure closure_mix(Closure cl1, Closure cl2, float fac)
 {
   Closure cl;
   cl.holdout = mix(cl1.holdout, cl2.holdout, fac);
+
+  if (FLAG_TEST(cl1.flag, CLOSURE_HOLDOUT_FLAG)) {
+    fac = 1.0;
+  }
+  else if (FLAG_TEST(cl2.flag, CLOSURE_HOLDOUT_FLAG)) {
+    fac = 0.0;
+  }
+
   cl.transmittance = mix(cl1.transmittance, cl2.transmittance, fac);
   cl.radiance = mix(cl1.radiance, cl2.radiance, fac);
   cl.flag = cl1.flag | cl2.flag;
@@ -958,7 +966,7 @@ void main()
 {
   Closure cl = nodetree_exec();
 
-  float holdout = 1.0 - saturate(cl.holdout);
+  float holdout = saturate(1.0 - cl.holdout);
   float transmit = saturate(avg(cl.transmittance));
   float alpha = 1.0 - transmit;
 
@@ -972,8 +980,9 @@ void main()
    * Since we do that using the blending pipeline we need to account for material transmittance. */
   vol_scatter -= vol_scatter * cl.transmittance;
 
-  outRadiance = vec4(cl.radiance * vol_transmit + vol_scatter, alpha * holdout);
-  outTransmittance = vec4(cl.transmittance, transmit * holdout);
+  cl.radiance = cl.radiance * holdout * vol_transmit + vol_scatter;
+  outRadiance = vec4(cl.radiance, alpha * holdout);
+  outTransmittance = vec4(cl.transmittance, transmit) * holdout;
 #    else
   outRadiance = vec4(cl.radiance, holdout);
   ssrNormals = cl.ssr_normal;