Cycles: Stop lamp sampling if the lamp isn't visible

Both spot and area light have large areas where they're not visible.
Therefore, this patch stops the light sampling code when one of these cases (outside of the spotlight cone or behind the area light) occurs, before the lamp shader is evaluated.
In the case of the area light, the solid angle sampling can also be skipped.

In a test scene with Sample All Lights and 18 Area lamps and 9 Spot lamps that all point away from the area that the camera sees, render time drops from 12sec to 5sec.

Reviewers: brecht, sergey, dingto, juicyfruit

Differential Revision: https://developer.blender.org/D2216

1 files changed, 36 insertions, 36 deletions

diff --git a/intern/cycles/kernel/kernel_path_surface.h b/intern/cycles/kernel/kernel_path_surface.h
index 250b8e92a45..27acf8166b3 100644
--- a/intern/cycles/kernel/kernel_path_surface.h
+++ b/intern/cycles/kernel/kernel_path_surface.h
@@ -54,15 +54,15 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 				path_branched_rng_2D(kg, &lamp_rng, state, j, num_samples, PRNG_LIGHT_U, &light_u, &light_v);
 
 				LightSample ls;
-				lamp_light_sample(kg, i, light_u, light_v, ccl_fetch(sd, P), &ls);
-
-				if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
-					/* trace shadow ray */
-					float3 shadow;
-
-					if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
-						/* accumulate */
-						path_radiance_accum_light(L, throughput*num_samples_inv, &L_light, shadow, num_samples_inv, state->bounce, is_lamp);
+				if(lamp_light_sample(kg, i, light_u, light_v, ccl_fetch(sd, P), &ls)) {
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+						/* trace shadow ray */
+						float3 shadow;
+
+						if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
+							/* accumulate */
+							path_radiance_accum_light(L, throughput*num_samples_inv, &L_light, shadow, num_samples_inv, state->bounce, is_lamp);
+						}
 					}
 				}
 			}
@@ -86,15 +86,15 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 					light_t = 0.5f*light_t;
 
 				LightSample ls;
-				light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls);
-
-				if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
-					/* trace shadow ray */
-					float3 shadow;
-
-					if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
-						/* accumulate */
-						path_radiance_accum_light(L, throughput*num_samples_inv, &L_light, shadow, num_samples_inv, state->bounce, is_lamp);
+				if(light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls)) {
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+						/* trace shadow ray */
+						float3 shadow;
+
+						if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
+							/* accumulate */
+							path_radiance_accum_light(L, throughput*num_samples_inv, &L_light, shadow, num_samples_inv, state->bounce, is_lamp);
+						}
 					}
 				}
 			}
@@ -107,16 +107,16 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 		path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
 
 		LightSample ls;
-		light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls);
-
-		/* sample random light */
-		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
-			/* trace shadow ray */
-			float3 shadow;
-
-			if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
-				/* accumulate */
-				path_radiance_accum_light(L, throughput*num_samples_adjust, &L_light, shadow, num_samples_adjust, state->bounce, is_lamp);
+		if(light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls)) {
+			/* sample random light */
+			if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+				/* trace shadow ray */
+				float3 shadow;
+
+				if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
+					/* accumulate */
+					path_radiance_accum_light(L, throughput*num_samples_adjust, &L_light, shadow, num_samples_adjust, state->bounce, is_lamp);
+				}
 			}
 		}
 	}
@@ -206,15 +206,15 @@ ccl_device_inline void kernel_path_surface_connect_light(KernelGlobals *kg, ccl_
 #endif
 
 	LightSample ls;
-	light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls);
-
-	if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
-		/* trace shadow ray */
-		float3 shadow;
+	if(light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls)) {
+		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+			/* trace shadow ray */
+			float3 shadow;
 
-		if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
-			/* accumulate */
-			path_radiance_accum_light(L, throughput, &L_light, shadow, 1.0f, state->bounce, is_lamp);
+			if(!shadow_blocked(kg, emission_sd, state, &light_ray, &shadow)) {
+				/* accumulate */
+				path_radiance_accum_light(L, throughput, &L_light, shadow, 1.0f, state->bounce, is_lamp);
+			}
 		}
 	}
 #endif