[Bf-blender-cvs] [d611cf92335] master: Fix mixed BSDF + BSSRDF sampling bug in path tracing, after 095a01a73a35.

[Brecht Van Lommel]

Commit: d611cf9233583a04b9168850ddbf708236de44b3
Author: Brecht Van Lommel
Date:   Fri Jan 26 18:31:36 2018 +0100
Branches: master
https://developer.blender.org/rBd611cf9233583a04b9168850ddbf708236de44b3

Fix mixed BSDF + BSSRDF sampling bug in path tracing, after 095a01a73a35.

Spotted by Ha Hyung-jin, thanks!

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

M	intern/cycles/kernel/kernel_shader.h

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

diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index 26d3fcf15b2..5f2f00c5ceb 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -611,6 +611,8 @@ void shader_bsdf_eval(KernelGlobals *kg,
 ccl_device_inline const ShaderClosure *shader_bsdf_pick(ShaderData *sd,
                                                         float *randu)
 {
+	/* Note the sampling here must match shader_bssrdf_pick,
+	 * since we reuse the same random number. */
 	int sampled = 0;
 
 	if(sd->num_closure > 1) {
@@ -620,7 +622,7 @@ ccl_device_inline const ShaderClosure *shader_bsdf_pick(ShaderData *sd,
 		for(int i = 0; i < sd->num_closure; i++) {
 			const ShaderClosure *sc = &sd->closure[i];
 
-			if(CLOSURE_IS_BSDF(sc->type)) {
+			if(CLOSURE_IS_BSDF_OR_BSSRDF(sc->type)) {
 				sum += sc->sample_weight;
 			}
 		}
@@ -631,7 +633,7 @@ ccl_device_inline const ShaderClosure *shader_bsdf_pick(ShaderData *sd,
 		for(int i = 0; i < sd->num_closure; i++) {
 			const ShaderClosure *sc = &sd->closure[i];
 
-			if(CLOSURE_IS_BSDF(sc->type)) {
+			if(CLOSURE_IS_BSDF_OR_BSSRDF(sc->type)) {
 				float next_sum = partial_sum + sc->sample_weight;
 
 				if(r < next_sum) {
@@ -648,13 +650,16 @@ ccl_device_inline const ShaderClosure *shader_bsdf_pick(ShaderData *sd,
 		}
 	}
 
-	return &sd->closure[sampled];
+	const ShaderClosure *sc = &sd->closure[sampled];
+	return CLOSURE_IS_BSDF(sc->type)? sc: NULL;
 }
 
 ccl_device_inline const ShaderClosure *shader_bssrdf_pick(ShaderData *sd,
                                                           ccl_addr_space float3 *throughput,
                                                           float *randu)
 {
+	/* Note the sampling here must match shader_bsdf_pick,
+	 * since we reuse the same random number. */
 	int sampled = 0;
 
 	if(sd->num_closure > 1) {
@@ -703,7 +708,8 @@ ccl_device_inline const ShaderClosure *shader_bssrdf_pick(ShaderData *sd,
 		}
 	}
 
-	return &sd->closure[sampled];
+	const ShaderClosure *sc = &sd->closure[sampled];
+	return CLOSURE_IS_BSSRDF(sc->type)? sc: NULL;
 }
 
 ccl_device_inline int shader_bsdf_sample(KernelGlobals *kg,