[Bf-blender-cvs] [73252d3f600] master: Fix T63701 Eevee: High Volumetric end distance darkens the image

[Clément Foucault]

Commit: 73252d3f60053bc3f949abaa08a5eb37fcd227a2
Author: Clément Foucault
Date:   Thu Jun 6 18:46:35 2019 +0200
Branches: master
https://developer.blender.org/rB73252d3f60053bc3f949abaa08a5eb37fcd227a2

Fix T63701 Eevee: High Volumetric end distance darkens the image

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

M	source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
M	source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl

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

diff --git a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
index 052fdbb43a2..4096fc2d511 100644
--- a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
@@ -50,7 +50,7 @@ void main()
 #endif
 
   volumeScattering = vec4(cl.scatter, 1.0);
-  volumeExtinction = vec4(max(vec3(1e-4), cl.absorption + cl.scatter), 1.0);
+  volumeExtinction = vec4(cl.absorption + cl.scatter, 1.0);
   volumeEmissive = vec4(cl.emission, 1.0);
 
   /* Do not add phase weight if no scattering. */
diff --git a/source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl b/source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl
index 83ed9067087..e756cafba52 100644
--- a/source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl
@@ -10,14 +10,14 @@ uniform sampler3D volumeExtinction;
 
 flat in int slice;
 
-layout(location = 0) out vec4 finalScattering;
-layout(location = 1) out vec4 finalTransmittance;
+layout(location = 0) out vec3 finalScattering;
+layout(location = 1) out vec3 finalTransmittance;
 
 void main()
 {
   /* Start with full transmittance and no scattered light. */
-  finalScattering = vec4(0.0);
-  finalTransmittance = vec4(1.0);
+  finalScattering = vec3(0.0);
+  finalTransmittance = vec3(1.0);
 
   vec3 tex_size = vec3(textureSize(volumeScattering, 0).xyz);
 
@@ -42,8 +42,8 @@ void main()
   for (int i = 0; i < slice; ++i) {
     ivec3 volume_cell = ivec3(gl_FragCoord.xy, i);
 
-    vec4 Lscat = texelFetch(volumeScattering, volume_cell, 0);
-    vec4 s_extinction = texelFetch(volumeExtinction, volume_cell, 0);
+    vec3 Lscat = texelFetch(volumeScattering, volume_cell, 0).rgb;
+    vec3 s_extinction = texelFetch(volumeExtinction, volume_cell, 0).rgb;
 
     float cell_depth = volume_z_to_view_z((float(i) + 1.0) / tex_size.z);
     float ray_len = orig_ray_len * cell_depth;
@@ -51,10 +51,10 @@ void main()
     /* Evaluate Scattering */
     float s_len = abs(ray_len - prev_ray_len);
     prev_ray_len = ray_len;
-    vec4 Tr = exp(-s_extinction * s_len);
+    vec3 Tr = exp(-s_extinction * s_len);
 
     /* integrate along the current step segment */
-    Lscat = (Lscat - Lscat * Tr) / s_extinction;
+    Lscat = (Lscat - Lscat * Tr) / max(vec3(1e-8), s_extinction);
     /* accumulate and also take into account the transmittance from previous steps */
     finalScattering += finalTransmittance * Lscat;