Cycles: shadow pass support. Note that this only takes into account lamps,

emitting objects or world lighting do not contribute to the shadow pass.

Consider this more as a pass useful for some compositing tricks, unlike
other lighting passes this pass can't be used to exactly reconstruct the
combined pass.

5 files changed, 31 insertions, 13 deletions

diff --git a/intern/cycles/kernel/kernel_accumulate.h b/intern/cycles/kernel/kernel_accumulate.h
index 7860913ce94..1e6605541ca 100644
--- a/intern/cycles/kernel/kernel_accumulate.h
+++ b/intern/cycles/kernel/kernel_accumulate.h
@@ -136,6 +136,7 @@ __device_inline void path_radiance_init(PathRadiance *L, int use_light_pass)
 		L->emission = make_float3(0.0f, 0.0f, 0.0f);
 		L->background = make_float3(0.0f, 0.0f, 0.0f);
 		L->ao = make_float3(0.0f, 0.0f, 0.0f);
+		L->shadow = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
 	}
 	else
 		L->emission = make_float3(0.0f, 0.0f, 0.0f);
@@ -215,26 +216,35 @@ __device_inline void path_radiance_accum_ao(PathRadiance *L, float3 throughput,
 #endif
 }
 
-__device_inline void path_radiance_accum_light(PathRadiance *L, float3 throughput, BsdfEval *bsdf_eval, int bounce)
+__device_inline void path_radiance_accum_light(PathRadiance *L, float3 throughput, BsdfEval *bsdf_eval, float3 shadow, int bounce, bool is_lamp)
 {
 #ifdef __PASSES__
 	if(L->use_light_pass) {
 		if(bounce == 0) {
 			/* directly visible lighting */
-			L->direct_diffuse += throughput*bsdf_eval->diffuse;
-			L->direct_glossy += throughput*bsdf_eval->glossy;
-			L->direct_transmission += throughput*bsdf_eval->transmission;
+			L->direct_diffuse += throughput*bsdf_eval->diffuse*shadow;
+			L->direct_glossy += throughput*bsdf_eval->glossy*shadow;
+			L->direct_transmission += throughput*bsdf_eval->transmission*shadow;
+
+			if(is_lamp) {
+				float3 sum = throughput*(bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission);
+
+				L->shadow.x += shadow.x;
+				L->shadow.y += shadow.y;
+				L->shadow.z += shadow.z;
+				L->shadow.w += average(sum);
+			}
 		}
 		else {
 			/* indirectly visible lighting after BSDF bounce */
 			float3 sum = bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission;
-			L->indirect += throughput*sum;
+			L->indirect += throughput*sum*shadow;
 		}
 	}
 	else
-		L->emission += throughput*bsdf_eval->diffuse;
+		L->emission += throughput*bsdf_eval->diffuse*shadow;
 #else
-	*L += throughput*(*bsdf_eval);
+	*L += throughput*(*bsdf_eval)*shadow;
 #endif
 }
 
diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index 2243858a403..764ac599991 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -60,7 +60,8 @@ __device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
 }
 
 __device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
-	float randt, float rando, float randu, float randv, Ray *ray, BsdfEval *eval)
+	float randt, float rando, float randu, float randv, Ray *ray, BsdfEval *eval,
+	bool *is_lamp)
 {
 	LightSample ls;
 
@@ -135,6 +136,8 @@ __device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
 		ray->t = 0.0f;
 	}
 
+	*is_lamp = (ls.prim == ~0);
+
 	return true;
 }
 
diff --git a/intern/cycles/kernel/kernel_passes.h b/intern/cycles/kernel/kernel_passes.h
index 44e06be8c16..51067630f09 100644
--- a/intern/cycles/kernel/kernel_passes.h
+++ b/intern/cycles/kernel/kernel_passes.h
@@ -132,6 +132,8 @@ __device_inline void kernel_write_light_passes(KernelGlobals *kg, __global float
 		kernel_write_pass_float3(buffer + kernel_data.film.pass_glossy_color, sample, L->color_glossy);
 	if(flag & PASS_TRANSMISSION_COLOR)
 		kernel_write_pass_float3(buffer + kernel_data.film.pass_transmission_color, sample, L->color_transmission);
+	if(flag & PASS_SHADOW)
+		kernel_write_pass_float4(buffer + kernel_data.film.pass_shadow, sample, L->shadow);
 #endif
 }
 
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 23860b41de3..f9eeccb1f11 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -327,6 +327,7 @@ __device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample, R
 
 				Ray light_ray;
 				BsdfEval L_light;
+				bool is_lamp;
 
 #ifdef __MULTI_LIGHT__
 				/* index -1 means randomly sample from distribution */
@@ -336,14 +337,13 @@ __device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample, R
 #else
 				const int i = -1;
 #endif
-					if(direct_emission(kg, &sd, i, light_t, light_o, light_u, light_v, &light_ray, &L_light)) {
+					if(direct_emission(kg, &sd, i, light_t, light_o, light_u, light_v, &light_ray, &L_light, &is_lamp)) {
 						/* trace shadow ray */
 						float3 shadow;
 
 						if(!shadow_blocked(kg, &state, &light_ray, &shadow)) {
 							/* accumulate */
-							bsdf_eval_mul(&L_light, shadow);
-							path_radiance_accum_light(&L, throughput, &L_light, state.bounce);
+							path_radiance_accum_light(&L, throughput, &L_light, shadow, state.bounce, is_lamp);
 						}
 					}
 #ifdef __MULTI_LIGHT__
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index c198ee1d24e..453d5c826e6 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -175,7 +175,8 @@ typedef enum PassType {
 	PASS_TRANSMISSION_DIRECT = 32768,
 	PASS_EMISSION = 65536,
 	PASS_BACKGROUND = 131072,
-	PASS_AO = 262144
+	PASS_AO = 262144,
+	PASS_SHADOW = 524288
 } PassType;
 
 #define PASS_ALL (~0)
@@ -206,6 +207,8 @@ typedef struct PathRadiance {
 	float3 indirect_diffuse;
 	float3 indirect_glossy;
 	float3 indirect_transmission;
+
+	float4 shadow;
 } PathRadiance;
 
 typedef struct BsdfEval {
@@ -464,7 +467,7 @@ typedef struct KernelFilm {
 	int pass_emission;
 	int pass_background;
 	int pass_ao;
-	int pass_pad2;
+	int pass_shadow;
 } KernelFilm;
 
 typedef struct KernelBackground {