Cycles / Ray Depth:

* Added a Ray Depth output to the Light Path node, which gives the user access to the current bounce.
This can be used to limit the maximum ray bounce on a per shader basis. Another use case is to restrict light influence with this, to have a lamp only contribute to the direct lighting. 

http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/More#Light_Path

This is part of my GSoC 2013 project. SVN merge of r58091 and r58772 from soc-2013-dingto. 

10 files changed, 54 insertions, 31 deletions

diff --git a/intern/cycles/kernel/kernel_displace.h b/intern/cycles/kernel/kernel_displace.h
index ae2e35e8d93..b4ece1610be 100644
--- a/intern/cycles/kernel/kernel_displace.h
+++ b/intern/cycles/kernel/kernel_displace.h
@@ -57,7 +57,7 @@ __device void kernel_shader_evaluate(KernelGlobals *kg, __global uint4 *input, _
 #endif
 
 		/* setup shader data */
-		shader_setup_from_background(kg, &sd, &ray);
+		shader_setup_from_background(kg, &sd, &ray, 0);
 
 		/* evaluate */
 		int flag = 0; /* we can't know which type of BSDF this is for */
diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index 77dc59d2691..a6bd3ed2850 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_noinline float3 direct_emissive_eval(KernelGlobals *kg, float rando,
-	LightSample *ls, float u, float v, float3 I, differential3 dI, float t, float time)
+	LightSample *ls, float u, float v, float3 I, differential3 dI, float t, float time, int bounce)
 {
 	/* setup shading at emitter */
 	ShaderData sd;
@@ -41,7 +41,7 @@ __device_noinline float3 direct_emissive_eval(KernelGlobals *kg, float rando,
 #ifdef __CAMERA_MOTION__
 		ray.time = time;
 #endif
-		shader_setup_from_background(kg, &sd, &ray);
+		shader_setup_from_background(kg, &sd, &ray, bounce+1);
 		eval = shader_eval_background(kg, &sd, 0, SHADER_CONTEXT_EMISSION);
 	}
 	else
@@ -49,10 +49,10 @@ __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, ls->prim);
+			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);
 		else
 #endif
-			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time, ~0);
+			shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time, bounce+1, ~0);
 
 		ls->Ng = sd.Ng;
 
@@ -74,7 +74,7 @@ __device_noinline float3 direct_emissive_eval(KernelGlobals *kg, float rando,
 
 __device_noinline bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
 	float randt, float rando, float randu, float randv, Ray *ray, BsdfEval *eval,
-	bool *is_lamp)
+	bool *is_lamp, int bounce)
 {
 	LightSample ls;
 
@@ -97,7 +97,7 @@ __device_noinline bool direct_emission(KernelGlobals *kg, ShaderData *sd, int li
 	differential3 dD = differential3_zero();
 
 	/* evaluate closure */
-	float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, dD, ls.t, sd->time);
+	float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, dD, ls.t, sd->time, bounce);
 
 	if(is_zero(light_eval))
 		return false;
@@ -185,7 +185,7 @@ __device_noinline float3 indirect_primitive_emission(KernelGlobals *kg, ShaderDa
 
 /* Indirect Lamp Emission */
 
-__device_noinline bool indirect_lamp_emission(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf, float randt, float3 *emission)
+__device_noinline bool indirect_lamp_emission(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf, float randt, float3 *emission, int bounce)
 {
 	LightSample ls;
 	int lamp = lamp_light_eval_sample(kg, randt);
@@ -209,7 +209,7 @@ __device_noinline bool indirect_lamp_emission(KernelGlobals *kg, Ray *ray, int p
 	/* 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);
+	float3 L = direct_emissive_eval(kg, 0.0f, &ls, u, v, -ray->D, ray->dD, ls.t, ray->time, bounce);
 
 	if(!(path_flag & PATH_RAY_MIS_SKIP)) {
 		/* multiple importance sampling, get regular light pdf,
@@ -224,7 +224,7 @@ __device_noinline bool indirect_lamp_emission(KernelGlobals *kg, Ray *ray, int p
 
 /* Indirect Background */
 
-__device_noinline float3 indirect_background(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf)
+__device_noinline float3 indirect_background(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf, int bounce)
 {
 #ifdef __BACKGROUND__
 	int shader = kernel_data.background.shader;
@@ -240,7 +240,7 @@ __device_noinline float3 indirect_background(KernelGlobals *kg, Ray *ray, int pa
 
 	/* evaluate background closure */
 	ShaderData sd;
-	shader_setup_from_background(kg, &sd, ray);
+	shader_setup_from_background(kg, &sd, ray, bounce+1);
 
 	float3 L = shader_eval_background(kg, &sd, path_flag, SHADER_CONTEXT_EMISSION);
 
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 0ef255786fa..40ecb1be91b 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -215,7 +215,7 @@ __device_inline bool shadow_blocked(KernelGlobals *kg, PathState *state, Ray *ra
 					return true;
 
 				ShaderData sd;
-				shader_setup_from_ray(kg, &sd, &isect, ray);
+				shader_setup_from_ray(kg, &sd, &isect, ray, state->bounce+1);
 				shader_eval_surface(kg, &sd, 0.0f, PATH_RAY_SHADOW, SHADER_CONTEXT_SHADOW);
 
 				throughput *= shader_bsdf_transparency(kg, &sd);
@@ -300,7 +300,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
 			float light_t = path_rng_1D(kg, rng, sample, num_samples, rng_offset + PRNG_LIGHT);
 			float3 emission;
 
-			if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission))
+			if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission, state.bounce))
 				path_radiance_accum_emission(&L, throughput, emission, state.bounce);
 		}
 #endif
@@ -318,7 +318,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
 
 #ifdef __BACKGROUND__
 			/* sample background shader */
-			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf);
+			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf, state.bounce);
 			path_radiance_accum_background(&L, throughput, L_background, state.bounce);
 #endif
 
@@ -327,7 +327,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
 
 		/* setup shading */
 		ShaderData sd;
-		shader_setup_from_ray(kg, &sd, &isect, &ray);
+		shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce);
 		float rbsdf = path_rng_1D(kg, rng, sample, num_samples, rng_offset + PRNG_BSDF);
 		shader_eval_surface(kg, &sd, rbsdf, state.flag, SHADER_CONTEXT_MAIN);
 
@@ -464,7 +464,7 @@ __device float4 kernel_path_progressive(KernelGlobals *kg, RNG *rng, int sample,
 				light_ray.time = sd.time;
 #endif
 
-				if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
+				if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp, state.bounce)) {
 					/* trace shadow ray */
 					float3 shadow;
 
@@ -575,7 +575,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
 			float light_t = path_rng_1D(kg, rng, sample, num_total_samples, rng_offset + PRNG_LIGHT);
 			float3 emission;
 
-			if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission))
+			if(indirect_lamp_emission(kg, &light_ray, state.flag, ray_pdf, light_t, &emission, state.bounce))
 				path_radiance_accum_emission(L, throughput, emission, state.bounce);
 		}
 #endif
@@ -583,7 +583,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
 		if(!hit) {
 #ifdef __BACKGROUND__
 			/* sample background shader */
-			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf);
+			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf, state.bounce);
 			path_radiance_accum_background(L, throughput, L_background, state.bounce);
 #endif
 
@@ -592,7 +592,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
 
 		/* setup shading */
 		ShaderData sd;
-		shader_setup_from_ray(kg, &sd, &isect, &ray);
+		shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce);
 		float rbsdf = path_rng_1D(kg, rng, sample, num_total_samples, rng_offset + PRNG_BSDF);
 		shader_eval_surface(kg, &sd, rbsdf, state.flag, SHADER_CONTEXT_INDIRECT);
 		shader_merge_closures(kg, &sd);
@@ -706,7 +706,7 @@ __device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, int sample, Ray
 #endif
 
 				/* sample random light */
-				if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
+				if(direct_emission(kg, &sd, -1, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp, state.bounce)) {
 					/* trace shadow ray */
 					float3 shadow;
 
@@ -838,7 +838,7 @@ __device_noinline void kernel_path_non_progressive_lighting(KernelGlobals *kg, R
 				float light_u, light_v;
 				path_rng_2D(kg, &lamp_rng, sample*num_samples + j, aa_samples*num_samples, rng_offset + PRNG_LIGHT_U, &light_u, &light_v);
 
-				if(direct_emission(kg, sd, i, 0.0f, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
+				if(direct_emission(kg, sd, i, 0.0f, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp, state.bounce)) {
 					/* trace shadow ray */
 					float3 shadow;
 
@@ -867,7 +867,7 @@ __device_noinline void kernel_path_non_progressive_lighting(KernelGlobals *kg, R
 				if(kernel_data.integrator.num_all_lights)
 					light_t = 0.5f*light_t;
 
-				if(direct_emission(kg, sd, -1, light_t, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
+				if(direct_emission(kg, sd, -1, light_t, 0.0f, light_u, light_v, &light_ray, &L_light, &is_lamp, state.bounce)) {
 					/* trace shadow ray */
 					float3 shadow;
 
@@ -1013,7 +1013,7 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
 
 #ifdef __BACKGROUND__
 			/* sample background shader */
-			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf);
+			float3 L_background = indirect_background(kg, &ray, state.flag, ray_pdf, state.bounce);
 			path_radiance_accum_background(&L, throughput, L_background, state.bounce);
 #endif
 
@@ -1022,7 +1022,7 @@ __device float4 kernel_path_non_progressive(KernelGlobals *kg, RNG *rng, int sam
 
 		/* setup shading */
 		ShaderData sd;
-		shader_setup_from_ray(kg, &sd, &isect, &ray);
+		shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce);
 		shader_eval_surface(kg, &sd, 0.0f, state.flag, SHADER_CONTEXT_MAIN);
 		shader_merge_closures(kg, &sd);
 
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index 039981a031a..b902230a9b9 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -64,7 +64,7 @@ __device_noinline
 __device
 #endif
 void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
-	const Intersection *isect, const Ray *ray)
+	const Intersection *isect, const Ray *ray, int bounce)
 {
 #ifdef __INSTANCING__
 	sd->object = (isect->object == ~0)? kernel_tex_fetch(__prim_object, isect->prim): isect->object;
@@ -80,6 +80,7 @@ void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
 
 	sd->prim = kernel_tex_fetch(__prim_index, isect->prim);
 	sd->ray_length = isect->t;
+	sd->ray_depth = bounce;
 
 #ifdef __HAIR__
 	if(kernel_tex_fetch(__prim_segment, isect->prim) != ~0) {
@@ -277,7 +278,7 @@ __device
 #endif
 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 t, float time, int segment)
+	int shader, int object, int prim, float u, float v, float t, float time, int bounce, int segment)
 {
 	/* vectors */
 	sd->P = P;
@@ -300,6 +301,7 @@ void shader_setup_from_sample(KernelGlobals *kg, ShaderData *sd,
 	sd->v = v;
 #endif
 	sd->ray_length = t;
+	sd->ray_depth = bounce;
 
 	/* detect instancing, for non-instanced the object index is -object-1 */
 #ifdef __INSTANCING__
@@ -408,12 +410,12 @@ __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, 0.0f, TIME_INVALID, ~0);
+	shader_setup_from_sample(kg, sd, P, Ng, I, shader, object, prim, u, v, 0.0f, TIME_INVALID, 0, ~0);
 }
 
 /* ShaderData setup from ray into background */
 
-__device_inline void shader_setup_from_background(KernelGlobals *kg, ShaderData *sd, const Ray *ray)
+__device_inline void shader_setup_from_background(KernelGlobals *kg, ShaderData *sd, const Ray *ray, int bounce)
 {
 	/* vectors */
 	sd->P = ray->D;
@@ -426,6 +428,7 @@ __device_inline void shader_setup_from_background(KernelGlobals *kg, ShaderData
 	sd->time = ray->time;
 #endif
 	sd->ray_length = 0.0f;
+	sd->ray_depth = bounce;
 
 #ifdef __INSTANCING__
 	sd->object = ~0;
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 38ababa96bd..733eb665860 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -540,6 +540,9 @@ typedef struct ShaderData {
 	
 	/* length of the ray being shaded */
 	float ray_length;
+	
+	/* ray bounce depth */
+	int ray_depth;
 
 #ifdef __RAY_DIFFERENTIALS__
 	/* differential of P. these are orthogonal to Ng, not N */
diff --git a/intern/cycles/kernel/osl/osl_services.cpp b/intern/cycles/kernel/osl/osl_services.cpp
index e1e43b117e7..f3b79da8894 100644
--- a/intern/cycles/kernel/osl/osl_services.cpp
+++ b/intern/cycles/kernel/osl/osl_services.cpp
@@ -84,6 +84,7 @@ ustring OSLRenderServices::u_curve_thickness("geom:curve_thickness");
 ustring OSLRenderServices::u_curve_tangent_normal("geom:curve_tangent_normal");
 #endif
 ustring OSLRenderServices::u_path_ray_length("path:ray_length");
+ustring OSLRenderServices::u_path_ray_depth("path:ray_depth");
 ustring OSLRenderServices::u_trace("trace");
 ustring OSLRenderServices::u_hit("hit");
 ustring OSLRenderServices::u_hitdist("hitdist");
@@ -660,6 +661,11 @@ bool OSLRenderServices::get_background_attribute(KernelGlobals *kg, ShaderData *
 		float f = sd->ray_length;
 		return set_attribute_float(f, type, derivatives, val);
 	}
+	else if (name == u_path_ray_depth) {
+		/* Ray Depth */
+		int f = sd->ray_depth;
+		return set_attribute_int(f, type, derivatives, val);
+	}
 	else if (name == u_ndc) {
 		/* NDC coordinates with special exception for otho */
 		OSLThreadData *tdata = kg->osl_tdata;
@@ -919,7 +925,10 @@ bool OSLRenderServices::getmessage(OSL::ShaderGlobals *sg, ustring source, ustri
 
 				if(!tracedata->setup) {
 					/* lazy shader data setup */
-					shader_setup_from_ray(kg, sd, &tracedata->isect, &tracedata->ray);
+					ShaderData *original_sd = (ShaderData *)(sg->renderstate);
+					int bounce = original_sd->ray_depth + 1;
+
+					shader_setup_from_ray(kg, sd, &tracedata->isect, &tracedata->ray, bounce);
 					tracedata->setup = true;
 				}
 
diff --git a/intern/cycles/kernel/osl/osl_services.h b/intern/cycles/kernel/osl/osl_services.h
index ca18c85a167..5ec4673ef37 100644
--- a/intern/cycles/kernel/osl/osl_services.h
+++ b/intern/cycles/kernel/osl/osl_services.h
@@ -135,6 +135,7 @@ public:
 	static ustring u_curve_thickness;
 	static ustring u_curve_tangent_normal;
 	static ustring u_path_ray_length;
+	static ustring u_path_ray_depth;
 	static ustring u_trace;
 	static ustring u_hit;
 	static ustring u_hitdist;
diff --git a/intern/cycles/kernel/shaders/node_light_path.osl b/intern/cycles/kernel/shaders/node_light_path.osl
index 9e3f6c7b4a9..ed3c6969970 100644
--- a/intern/cycles/kernel/shaders/node_light_path.osl
+++ b/intern/cycles/kernel/shaders/node_light_path.osl
@@ -26,7 +26,8 @@ shader node_light_path(
 	output float IsSingularRay = 0.0,
 	output float IsReflectionRay = 0.0,
 	output float IsTransmissionRay = 0.0,
-	output float RayLength = 0.0)
+	output float RayLength = 0.0,
+	output float RayDepth = 0.0)
 {
 	IsCameraRay = raytype("camera");
 	IsShadowRay = raytype("shadow");
@@ -37,5 +38,9 @@ shader node_light_path(
 	IsTransmissionRay = raytype("refraction");
 
 	getattribute("path:ray_length", RayLength);
+
+	int ray_depth;
+	getattribute("path:ray_depth", ray_depth);
+	RayDepth = (float)ray_depth;
 }
 
diff --git a/intern/cycles/kernel/svm/svm_light_path.h b/intern/cycles/kernel/svm/svm_light_path.h
index b29dc9cbd45..0f16ef83894 100644
--- a/intern/cycles/kernel/svm/svm_light_path.h
+++ b/intern/cycles/kernel/svm/svm_light_path.h
@@ -34,6 +34,7 @@ __device void svm_node_light_path(ShaderData *sd, float *stack, uint type, uint
 		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;
+		case NODE_LP_ray_depth: info = (float)sd->ray_depth; 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 e5b3e2b972f..85719265292 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -153,7 +153,8 @@ typedef enum NodeLightPath {
 	NODE_LP_reflection,
 	NODE_LP_transmission,
 	NODE_LP_backfacing,
-	NODE_LP_ray_length
+	NODE_LP_ray_length,
+	NODE_LP_ray_depth
 } NodeLightPath;
 
 typedef enum NodeLightFalloff {