Fix T36979: wrong render of textured mesh lights with multiple importance sampling.

3 files changed, 24 insertions, 21 deletions

diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index 1ec116b7635..58bdc2b70ca 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -19,7 +19,7 @@ CCL_NAMESPACE_BEGIN
 /* Direction Emission */
 
 ccl_device_noinline float3 direct_emissive_eval(KernelGlobals *kg, float rando,
-	LightSample *ls, float u, float v, float3 I, differential3 dI, float t, float time, int bounce)
+	LightSample *ls, float3 I, differential3 dI, float t, float time, int bounce)
 {
 	/* setup shading at emitter */
 	ShaderData sd;
@@ -47,10 +47,10 @@ ccl_device_noinline float3 direct_emissive_eval(KernelGlobals *kg, float rando,
 	{
 #ifdef __HAIR__
 		if(ls->type == LIGHT_STRAND)
-			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time, bounce+1, ls->prim);
+			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, ls->u, ls->v, t, time, bounce+1, ls->prim);
 		else
 #endif
-			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time, bounce+1, ~0);
+			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, ls->u, ls->v, t, time, bounce+1, ~0);
 
 		ls->Ng = sd.Ng;
 
@@ -95,7 +95,7 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg, ShaderData *sd, int
 	differential3 dD = differential3_zero();
 
 	/* evaluate closure */
-	float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, dD, ls.t, sd->time, bounce);
+	float3 light_eval = direct_emissive_eval(kg, rando, &ls, -ls.D, dD, ls.t, sd->time, bounce);
 
 	if(is_zero(light_eval))
 		return false;
@@ -211,10 +211,7 @@ ccl_device_noinline bool indirect_lamp_emission(KernelGlobals *kg, Ray *ray, int
 	}
 #endif
 
-	/* todo: missing texture coordinates */
-	float u = 0.0f;
-	float v = 0.0f;
-	float3 L = direct_emissive_eval(kg, 0.0f, &ls, u, v, -ray->D, ray->dD, ls.t, ray->time, bounce);
+	float3 L = direct_emissive_eval(kg, 0.0f, &ls, -ray->D, ray->dD, ls.t, ray->time, bounce);
 
 	if(!(path_flag & PATH_RAY_MIS_SKIP)) {
 		/* multiple importance sampling, get regular light pdf,
diff --git a/intern/cycles/kernel/kernel_light.h b/intern/cycles/kernel/kernel_light.h
index 9915cd2495f..c32f0395744 100644
--- a/intern/cycles/kernel/kernel_light.h
+++ b/intern/cycles/kernel/kernel_light.h
@@ -23,6 +23,7 @@ typedef struct LightSample {
 	float3 Ng;			/* normal on light */
 	float3 D;			/* direction from shading point to light */
 	float t;			/* distance to light (FLT_MAX for distant light) */
+	float u, v;			/* parametric coordinate on primitive */
 	float pdf;			/* light sampling probability density function */
 	float eval_fac;		/* intensity multiplier */
 	int object;			/* object id for triangle/curve lights */
@@ -219,6 +220,8 @@ ccl_device void lamp_light_sample(KernelGlobals *kg, int lamp,
 	ls->object = ~0;
 	ls->prim = ~0;
 	ls->lamp = lamp;
+	ls->u = randu;
+	ls->v = randv;
 
 	if(type == LIGHT_DISTANT) {
 		/* distant light */
@@ -309,6 +312,9 @@ ccl_device bool lamp_light_eval(KernelGlobals *kg, int lamp, float3 P, float3 D,
 	ls->object = ~0;
 	ls->prim = ~0;
 	ls->lamp = lamp;
+	/* todo: missing texture coordinates */
+	ls->u = 0.0f;
+	ls->v = 0.0f;
 
 	if(!(ls->shader & SHADER_USE_MIS))
 		return false;
@@ -443,14 +449,24 @@ ccl_device void object_transform_light_sample(KernelGlobals *kg, LightSample *ls
 ccl_device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
 	float randu, float randv, float time, LightSample *ls)
 {
+	float u, v;
+
+	/* compute random point in triangle */
+	randu = sqrtf(randu);
+
+	u = 1.0f - randu;
+	v = randv*randu;
+
 	/* triangle, so get position, normal, shader */
-	ls->P = triangle_sample_MT(kg, prim, randu, randv);
+	ls->P = triangle_point_MT(kg, prim, u, v);
 	ls->Ng = triangle_normal_MT(kg, prim, &ls->shader);
 	ls->object = object;
 	ls->prim = prim;
 	ls->lamp = ~0;
 	ls->shader |= SHADER_USE_MIS;
 	ls->t = 0.0f;
+	ls->u = u;
+	ls->v = v;
 	ls->type = LIGHT_TRIANGLE;
 	ls->eval_fac = 1.0f;
 
@@ -504,6 +520,8 @@ ccl_device void curve_segment_light_sample(KernelGlobals *kg, int prim, int obje
 	ls->prim = prim;
 	ls->lamp = ~0;
 	ls->t = 0.0f;
+	ls->u = randu;
+	ls->v = randv;
 	ls->type = LIGHT_STRAND;
 	ls->eval_fac = 1.0f;
 	ls->shader = __float_as_int(v00.z) | SHADER_USE_MIS;
diff --git a/intern/cycles/kernel/kernel_triangle.h b/intern/cycles/kernel/kernel_triangle.h
index d457b67e77e..0455df85961 100644
--- a/intern/cycles/kernel/kernel_triangle.h
+++ b/intern/cycles/kernel/kernel_triangle.h
@@ -31,18 +31,6 @@ ccl_device_inline float3 triangle_point_MT(KernelGlobals *kg, int tri_index, flo
 	return (u*v0 + v*v1 + t*v2);
 }
 
-/* Sample point on triangle */
-ccl_device_inline float3 triangle_sample_MT(KernelGlobals *kg, int tri_index, float randu, float randv)
-{
-	/* compute point */
-	randu = sqrtf(randu);
-
-	float u = 1.0f - randu;
-	float v = randv*randu;
-
-	return triangle_point_MT(kg, tri_index, u, v);
-}
-
 /* Normal for Moller-Trumbore triangles */
 ccl_device_inline float3 triangle_normal_MT(KernelGlobals *kg, int tri_index, int *shader)
 {