Cycles: make multiple importance sampling for lamps an option per lamp now,

disabled by default for backwards compatibility.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Integrator

4 files changed, 13 insertions, 39 deletions

diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index 54bc0717b60..e234d54e228 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -93,7 +93,7 @@ __device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
 	}
 
 	/* return lamp index for MIS */
-	if(ls.use_mis)
+	if(ls.shader & SHADER_USE_MIS)
 		*lamp = ls.lamp;
 	else
 		*lamp= ~0;
@@ -114,7 +114,7 @@ __device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
 
 	shader_bsdf_eval(kg, sd, ls.D, eval, &bsdf_pdf);
 
-	if(ls.use_mis) {
+	if(ls.shader & SHADER_USE_MIS) {
 		/* multiple importance sampling */
 		float mis_weight = power_heuristic(ls.pdf, bsdf_pdf);
 		light_eval *= mis_weight;
diff --git a/intern/cycles/kernel/kernel_light.h b/intern/cycles/kernel/kernel_light.h
index 6ba3e439329..8b32b7bd2e8 100644
--- a/intern/cycles/kernel/kernel_light.h
+++ b/intern/cycles/kernel/kernel_light.h
@@ -31,7 +31,6 @@ typedef struct LightSample {
 	int prim;			/* primitive id for triangle/curve ligths */
 	int shader;			/* shader id */
 	int lamp;			/* lamp id */
-	int use_mis;		/* for lamps with size zero */
 	LightType type;		/* type of light */
 } LightSample;
 
@@ -218,11 +217,10 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 
 	LightType type = (LightType)__float_as_int(data0.x);
 	ls->type = type;
-#ifdef __LAMP_MIS__
-	ls->use_mis = true;
-#else
-	ls->use_mis = false;
-#endif
+	ls->shader = __float_as_int(data1.x);
+	ls->object = ~0;
+	ls->prim = ~0;
+	ls->lamp = lamp;
 
 	if(type == LIGHT_DISTANT) {
 		/* distant light */
@@ -233,10 +231,6 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 
 		if(radius > 0.0f)
 			D = distant_light_sample(D, radius, randu, randv);
-#ifdef __LAMP_MIS__
-		else
-			ls->use_mis = false;
-#endif
 
 		ls->P = D;
 		ls->Ng = D;
@@ -257,9 +251,6 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 		ls->D = -D;
 		ls->t = FLT_MAX;
 		ls->eval_fac = 1.0f;
-#ifndef __LAMP_MIS__
-		ls->use_mis = true;
-#endif
 	}
 #endif
 	else {
@@ -271,10 +262,6 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 			if(radius > 0.0f)
 				/* sphere light */
 				ls->P += sphere_light_sample(P, ls->P, radius, randu, randv);
-#ifdef __LAMP_MIS__
-			else
-				ls->use_mis = false;
-#endif
 
 			ls->D = normalize_len(ls->P - P, &ls->t);
 			ls->Ng = -ls->D;
@@ -304,13 +291,6 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 
 			float invarea = data2.x;
 
-			if(invarea == 0.0f) {
-#ifdef __LAMP_MIS__
-				ls->use_mis = false;
-#endif
-				invarea = 1.0f;
-			}
-
 			ls->eval_fac = 0.25f*invarea;
 			ls->pdf = invarea;
 		}
@@ -318,11 +298,6 @@ __device void lamp_light_sample(KernelGlobals *kg, int lamp,
 		ls->eval_fac *= kernel_data.integrator.inv_pdf_lights;
 		ls->pdf *= lamp_light_pdf(kg, ls->Ng, -ls->D, ls->t);
 	}
-
-	ls->shader = __float_as_int(data1.x);
-	ls->object = ~0;
-	ls->prim = ~0;
-	ls->lamp = lamp;
 }
 
 __device bool lamp_light_eval(KernelGlobals *kg, int lamp, float3 P, float3 D, float t, LightSample *ls)
@@ -336,7 +311,6 @@ __device bool lamp_light_eval(KernelGlobals *kg, int lamp, float3 P, float3 D, f
 	ls->object = ~0;
 	ls->prim = ~0;
 	ls->lamp = lamp;
-	ls->use_mis = false; /* flag not used for eval */
 
 	if(type == LIGHT_DISTANT) {
 		/* distant light */
@@ -475,7 +449,7 @@ __device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
 	ls->object = object;
 	ls->prim = prim;
 	ls->lamp = ~0;
-	ls->use_mis = true;
+	ls->shader |= SHADER_USE_MIS;
 	ls->t = 0.0f;
 	ls->type = LIGHT_AREA;
 	ls->eval_fac = 1.0f;
@@ -529,11 +503,10 @@ __device void curve_segment_light_sample(KernelGlobals *kg, int prim, int object
 	ls->object = object;
 	ls->prim = prim;
 	ls->lamp = ~0;
-	ls->use_mis = true;
 	ls->t = 0.0f;
 	ls->type = LIGHT_STRAND;
 	ls->eval_fac = 1.0f;
-	ls->shader = __float_as_int(v00.z);
+	ls->shader = __float_as_int(v00.z) | SHADER_USE_MIS;
 
 	object_transform_light_sample(kg, ls, object, time);
 }
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 1a5df66e6c2..06276c8167a 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -254,7 +254,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
 		bool hit = scene_intersect(kg, &ray, visibility, &isect);
 
 #ifdef __LAMP_MIS__
-		if(kernel_data.integrator.pdf_lights > 0.0f && !(state.flag & PATH_RAY_CAMERA)) {
+		if(kernel_data.integrator.use_lamp_mis && !(state.flag & PATH_RAY_CAMERA)) {
 			/* ray starting from previous non-transparent bounce */
 			Ray light_ray;
 
@@ -501,7 +501,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
 		bool hit = scene_intersect(kg, &ray, visibility, &isect);
 
 #ifdef __LAMP_MIS__
-		if(kernel_data.integrator.pdf_lights > 0.0f && !(state.flag & PATH_RAY_CAMERA)) {
+		if(kernel_data.integrator.use_lamp_mis && !(state.flag & PATH_RAY_CAMERA)) {
 			/* ray starting from previous non-transparent bounce */
 			Ray light_ray;
 
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 1236f43e018..2ef3d71dd1d 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -288,8 +288,9 @@ typedef enum ShaderFlag {
 	SHADER_SMOOTH_NORMAL = (1 << 31),
 	SHADER_CAST_SHADOW = (1 << 30),
 	SHADER_AREA_LIGHT = (1 << 29),
+	SHADER_USE_MIS = (1 << 28),
 
-	SHADER_MASK = ~(SHADER_SMOOTH_NORMAL|SHADER_CAST_SHADOW|SHADER_AREA_LIGHT)
+	SHADER_MASK = ~(SHADER_SMOOTH_NORMAL|SHADER_CAST_SHADOW|SHADER_AREA_LIGHT|SHADER_USE_MIS)
 } ShaderFlag;
 
 /* Light Type */
@@ -680,7 +681,7 @@ typedef struct KernelIntegrator {
 	int transmission_samples;
 	int ao_samples;
 	int mesh_light_samples;
-	int pad1;
+	int use_lamp_mis;
 } KernelIntegrator;
 
 typedef struct KernelBVH {