[Bf-blender-cvs] [7230866] master: Fix T39284: clamp cycles volume density to be >= 0, to avoid accidental strange shading.

[Brecht Van Lommel]

Commit: 72308669cebd401535bc533a6c1af9e6f420438e
Author: Brecht Van Lommel
Date:   Tue Apr 15 14:33:13 2014 +0200
https://developer.blender.org/rB72308669cebd401535bc533a6c1af9e6f420438e

Fix T39284: clamp cycles volume density to be >= 0, to avoid accidental strange shading.

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

M	intern/cycles/kernel/shaders/node_absorption_volume.osl
M	intern/cycles/kernel/shaders/node_scatter_volume.osl
M	intern/cycles/kernel/svm/svm_closure.h

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

diff --git a/intern/cycles/kernel/shaders/node_absorption_volume.osl b/intern/cycles/kernel/shaders/node_absorption_volume.osl
index 69c4c0e..6bac83b 100644
--- a/intern/cycles/kernel/shaders/node_absorption_volume.osl
+++ b/intern/cycles/kernel/shaders/node_absorption_volume.osl
@@ -21,6 +21,6 @@ shader node_absorption_volume(
 	float Density = 1.0,
 	output closure color Volume = 0)
 {
-	Volume = ((color(1.0, 1.0, 1.0) - Color) * Density) * absorption();
+	Volume = ((color(1.0, 1.0, 1.0) - Color) * max(Density, 0.0)) * absorption();
 }
 
diff --git a/intern/cycles/kernel/shaders/node_scatter_volume.osl b/intern/cycles/kernel/shaders/node_scatter_volume.osl
index bf23abb..77c157b 100644
--- a/intern/cycles/kernel/shaders/node_scatter_volume.osl
+++ b/intern/cycles/kernel/shaders/node_scatter_volume.osl
@@ -22,6 +22,6 @@ shader node_scatter_volume(
 	float Anisotropy = 0.0,
 	output closure color Volume = 0)
 {
-	Volume = (Color * Density) * henyey_greenstein(Anisotropy);
+	Volume = (Color * max(Density, 0.0)) * henyey_greenstein(Anisotropy);
 }
 
diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index fb1a981..ab9927f 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -498,7 +498,7 @@ ccl_device void svm_node_closure_volume(KernelGlobals *kg, ShaderData *sd, float
 
 	float param1 = (stack_valid(param1_offset))? stack_load_float(stack, param1_offset): __uint_as_float(node.z);
 	float param2 = (stack_valid(param2_offset))? stack_load_float(stack, param2_offset): __uint_as_float(node.w);
-	float density = param1;
+	float density = fmaxf(param1, 0.0f);
 
 	switch(type) {
 		case CLOSURE_VOLUME_ABSORPTION_ID: {