5 files changed, 14 insertions, 6 deletions

diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index cd7701a0c75..0ef1425e68a 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -21,7 +21,7 @@ CCL_NAMESPACE_BEGIN
 /* Direction Emission */
 
 __device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
-	LightSample *ls, float u, float v, float3 I, float time)
+	LightSample *ls, float u, float v, float3 I, float t, float time)
 {
 	/* setup shading at emitter */
 	ShaderData sd;
@@ -40,7 +40,7 @@ __device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
 	else
 #endif
 	{
-		shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, time);
+		shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time);
 		ls->Ng = sd.Ng;
 
 		/* no path flag, we're evaluating this for all closures. that's weak but
@@ -87,7 +87,7 @@ __device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
 		return false;
 
 	/* evaluate closure */
-	float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, sd->time);
+	float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, ls.t, sd->time);
 
 	if(is_zero(light_eval))
 		return false;
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index e4edc480272..af821bad868 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -77,6 +77,7 @@ __device_inline void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
 	sd->N = Ng;
 	sd->I = -ray->D;
 	sd->shader = shader;
+	sd->ray_length = isect->t;
 
 	/* smooth normal */
 	if(sd->shader & SHADER_SMOOTH_NORMAL)
@@ -127,7 +128,7 @@ __device_inline void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
 
 __device void shader_setup_from_sample(KernelGlobals *kg, ShaderData *sd,
 	const float3 P, const float3 Ng, const float3 I,
-	int shader, int object, int prim, float u, float v, float time)
+	int shader, int object, int prim, float u, float v, float t, float time)
 {
 	/* vectors */
 	sd->P = P;
@@ -145,6 +146,7 @@ __device void shader_setup_from_sample(KernelGlobals *kg, ShaderData *sd,
 	sd->u = u;
 	sd->v = v;
 #endif
+	sd->ray_length = t;
 
 	/* detect instancing, for non-instanced the object index is -object-1 */
 #ifdef __INSTANCING__
@@ -242,7 +244,7 @@ __device void shader_setup_from_displace(KernelGlobals *kg, ShaderData *sd,
 
 	/* watch out: no instance transform currently */
 
-	shader_setup_from_sample(kg, sd, P, Ng, I, shader, object, prim, u, v, TIME_INVALID);
+	shader_setup_from_sample(kg, sd, P, Ng, I, shader, object, prim, u, v, 0.0f, TIME_INVALID);
 }
 
 /* ShaderData setup from ray into background */
@@ -259,6 +261,7 @@ __device_inline void shader_setup_from_background(KernelGlobals *kg, ShaderData
 #ifdef __MOTION__
 	sd->time = ray->time;
 #endif
+	sd->ray_length = 0.0f;
 
 #ifdef __INSTANCING__
 	sd->object = ~0;
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index bf48ec8c000..85ee16fc5c6 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -401,6 +401,9 @@ typedef struct ShaderData {
 
 	/* motion blur sample time */
 	float time;
+	
+	/* length of the ray being shaded */
+	float ray_length;
 
 #ifdef __MOTION__
 	/* object <-> world space transformations, cached to avoid
diff --git a/intern/cycles/kernel/svm/svm_light_path.h b/intern/cycles/kernel/svm/svm_light_path.h
index 1b13fd93a0f..ebbcb5be61f 100644
--- a/intern/cycles/kernel/svm/svm_light_path.h
+++ b/intern/cycles/kernel/svm/svm_light_path.h
@@ -33,6 +33,7 @@ __device void svm_node_light_path(ShaderData *sd, float *stack, uint type, uint
 		case NODE_LP_reflection: info = (path_flag & PATH_RAY_REFLECT)? 1.0f: 0.0f; break;
 		case NODE_LP_transmission: info = (path_flag & PATH_RAY_TRANSMIT)? 1.0f: 0.0f; break;
 		case NODE_LP_backfacing: info = (sd->flag & SD_BACKFACING)? 1.0f: 0.0f; break;
+		case NODE_LP_ray_length: info = sd->ray_length; break;
 	}
 
 	stack_store_float(stack, out_offset, info);
diff --git a/intern/cycles/kernel/svm/svm_types.h b/intern/cycles/kernel/svm/svm_types.h
index fa7c211b5f9..8037c3964a9 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -115,7 +115,8 @@ typedef enum NodeLightPath {
 	NODE_LP_singular,
 	NODE_LP_reflection,
 	NODE_LP_transmission,
-	NODE_LP_backfacing
+	NODE_LP_backfacing,
+	NODE_LP_ray_length
 } NodeLightPath;
 
 typedef enum NodeTexCoord {