[Bf-blender-cvs] [a201b99c5a] master: Fix T50975: Cycles: Light sampling threshold inadvertently clamps negative lamps

[Sergey Sharybin]

Commit: a201b99c5aaa7945bd0702c42987a60e3d70ee46
Author: Sergey Sharybin
Date:   Mon Mar 20 14:48:37 2017 +0100
Branches: master
https://developer.blender.org/rBa201b99c5aaa7945bd0702c42987a60e3d70ee46

Fix T50975: Cycles: Light sampling threshold inadvertently clamps negative lamps

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

M	intern/cycles/kernel/kernel_emission.h

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

diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index bc2d960412..cf14a159e4 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -157,7 +157,7 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg,
 		return false;
 
 	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
-		float probability = max3(bsdf_eval_sum(eval)) * kernel_data.integrator.light_inv_rr_threshold;
+		float probability = max3(fabs(bsdf_eval_sum(eval))) * kernel_data.integrator.light_inv_rr_threshold;
 		if(probability < 1.0f) {
 			if(rand_terminate >= probability) {
 				return false;