Code cleanup: remove hack to avoid seeing transparent objects in noise.

Previously the Sobol pattern suffered from some correlation issues that
made the outline of objects like a smoke domain visible. This helps
simplify the code and also makes some other optimizations possible.

8 files changed, 32 insertions, 67 deletions

diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 3a242a06a72..2c79f5892e6 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -210,8 +210,8 @@ ccl_device_forceinline VolumeIntegrateResult kernel_path_volume(
 				/* indirect sample. if we use distance sampling and take just
 				 * one sample for direct and indirect light, we could share
 				 * this computation, but makes code a bit complex */
-				float rphase = path_state_rng_1D_for_decision(kg, state, PRNG_PHASE);
-				float rscatter = path_state_rng_1D_for_decision(kg, state, PRNG_SCATTER_DISTANCE);
+				float rphase = path_state_rng_1D(kg, state, PRNG_PHASE);
+				float rscatter = path_state_rng_1D(kg, state, PRNG_SCATTER_DISTANCE);
 
 				result = kernel_volume_decoupled_scatter(kg,
 					state, &volume_ray, sd, throughput,
@@ -434,7 +434,7 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg,
 		                      sd,
 		                      &isect,
 		                      ray);
-		float rbsdf = path_state_rng_1D_for_decision(kg, state, PRNG_BSDF);
+		float rbsdf = path_state_rng_1D(kg, state, PRNG_BSDF);
 		shader_eval_surface(kg, sd, state, rbsdf, state->flag);
 #ifdef __BRANCHED_PATH__
 		shader_merge_closures(sd);
@@ -462,7 +462,7 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg,
 			break;
 		}
 		else if(probability != 1.0f) {
-			float terminate = path_state_rng_1D_for_decision(kg, state, PRNG_TERMINATE);
+			float terminate = path_state_rng_1D(kg, state, PRNG_TERMINATE);
 
 			if(terminate >= probability)
 				break;
@@ -591,7 +591,7 @@ ccl_device_forceinline void kernel_path_integrate(
 
 		/* Setup and evaluate shader. */
 		shader_setup_from_ray(kg, &sd, &isect, ray);
-		float rbsdf = path_state_rng_1D_for_decision(kg, state, PRNG_BSDF);
+		float rbsdf = path_state_rng_1D(kg, state, PRNG_BSDF);
 		shader_eval_surface(kg, &sd, state, rbsdf, state->flag);
 
 		/* Apply shadow catcher, holdout, emission. */
@@ -616,7 +616,7 @@ ccl_device_forceinline void kernel_path_integrate(
 			break;
 		}
 		else if(probability != 1.0f) {
-			float terminate = path_state_rng_1D_for_decision(kg, state, PRNG_TERMINATE);
+			float terminate = path_state_rng_1D(kg, state, PRNG_TERMINATE);
 			if(terminate >= probability)
 				break;
 
diff --git a/intern/cycles/kernel/kernel_path_branched.h b/intern/cycles/kernel/kernel_path_branched.h
index 3994d8d4954..e525e008945 100644
--- a/intern/cycles/kernel/kernel_path_branched.h
+++ b/intern/cycles/kernel/kernel_path_branched.h
@@ -339,8 +339,8 @@ ccl_device void kernel_branched_path_integrate(KernelGlobals *kg,
 					/* scatter sample. if we use distance sampling and take just one
 					 * sample for direct and indirect light, we could share this
 					 * computation, but makes code a bit complex */
-					float rphase = path_state_rng_1D_for_decision(kg, &ps, PRNG_PHASE);
-					float rscatter = path_state_rng_1D_for_decision(kg, &ps, PRNG_SCATTER_DISTANCE);
+					float rphase = path_state_rng_1D(kg, &ps, PRNG_PHASE);
+					float rscatter = path_state_rng_1D(kg, &ps, PRNG_SCATTER_DISTANCE);
 
 					VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
 						&ps, &pray, &sd, &tp, rphase, rscatter, &volume_segment, NULL, false);
@@ -466,7 +466,7 @@ ccl_device void kernel_branched_path_integrate(KernelGlobals *kg,
 				break;
 			}
 			else if(probability != 1.0f) {
-				float terminate = path_state_rng_1D_for_decision(kg, &state, PRNG_TERMINATE);
+				float terminate = path_state_rng_1D(kg, &state, PRNG_TERMINATE);
 
 				if(terminate >= probability)
 					break;
diff --git a/intern/cycles/kernel/kernel_path_state.h b/intern/cycles/kernel/kernel_path_state.h
index bb09b4ac080..eccee54c0e3 100644
--- a/intern/cycles/kernel/kernel_path_state.h
+++ b/intern/cycles/kernel/kernel_path_state.h
@@ -76,12 +76,12 @@ ccl_device_inline void path_state_next(KernelGlobals *kg, ccl_addr_space PathSta
 		state->flag |= PATH_RAY_TRANSPARENT;
 		state->transparent_bounce++;
 
-		/* don't increase random number generator offset here, to avoid some
-		 * unwanted patterns, see path_state_rng_1D_for_decision */
-
 		if(!kernel_data.integrator.transparent_shadows)
 			state->flag |= PATH_RAY_MIS_SKIP;
 
+		/* random number generator next bounce */
+		state->rng_offset += PRNG_BOUNCE_NUM;
+
 		return;
 	}
 
diff --git a/intern/cycles/kernel/kernel_path_volume.h b/intern/cycles/kernel/kernel_path_volume.h
index e7e24f853c2..f645a109ce9 100644
--- a/intern/cycles/kernel/kernel_path_volume.h
+++ b/intern/cycles/kernel/kernel_path_volume.h
@@ -155,8 +155,8 @@ ccl_device void kernel_branched_path_volume_connect_light(
 				float3 tp = throughput;
 
 				/* sample position on volume segment */
-				float rphase = path_branched_rng_1D_for_decision(kg, state->rng_hash, state, j, num_samples, PRNG_PHASE);
-				float rscatter = path_branched_rng_1D_for_decision(kg, state->rng_hash, state, j, num_samples, PRNG_SCATTER_DISTANCE);
+				float rphase = path_branched_rng_1D(kg, state->rng_hash, state, j, num_samples, PRNG_PHASE);
+				float rscatter = path_branched_rng_1D(kg, state->rng_hash, state, j, num_samples, PRNG_SCATTER_DISTANCE);
 
 				VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
 					state, ray, sd, &tp, rphase, rscatter, segment, (ls.t != FLT_MAX)? &ls.P: NULL, false);
@@ -201,8 +201,8 @@ ccl_device void kernel_branched_path_volume_connect_light(
 				float3 tp = throughput;
 
 				/* sample position on volume segment */
-				float rphase = path_branched_rng_1D_for_decision(kg, state->rng_hash, state, j, num_samples, PRNG_PHASE);
-				float rscatter = path_branched_rng_1D_for_decision(kg, state->rng_hash, state, j, num_samples, PRNG_SCATTER_DISTANCE);
+				float rphase = path_branched_rng_1D(kg, state->rng_hash, state, j, num_samples, PRNG_PHASE);
+				float rscatter = path_branched_rng_1D(kg, state->rng_hash, state, j, num_samples, PRNG_SCATTER_DISTANCE);
 
 				VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
 					state, ray, sd, &tp, rphase, rscatter, segment, (ls.t != FLT_MAX)? &ls.P: NULL, false);
@@ -238,8 +238,8 @@ ccl_device void kernel_branched_path_volume_connect_light(
 		float3 tp = throughput;
 
 		/* sample position on volume segment */
-		float rphase = path_state_rng_1D_for_decision(kg, state, PRNG_PHASE);
-		float rscatter = path_state_rng_1D_for_decision(kg, state, PRNG_SCATTER_DISTANCE);
+		float rphase = path_state_rng_1D(kg, state, PRNG_PHASE);
+		float rscatter = path_state_rng_1D(kg, state, PRNG_SCATTER_DISTANCE);
 
 		VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
 			state, ray, sd, &tp, rphase, rscatter, segment, (ls.t != FLT_MAX)? &ls.P: NULL, false);
diff --git a/intern/cycles/kernel/kernel_random.h b/intern/cycles/kernel/kernel_random.h
index b35ed3bd279..eb23c77d6a4 100644
--- a/intern/cycles/kernel/kernel_random.h
+++ b/intern/cycles/kernel/kernel_random.h
@@ -186,25 +186,6 @@ ccl_device_inline float path_state_rng_1D(KernelGlobals *kg,
 	                   state->rng_offset + dimension);
 }
 
-ccl_device_inline float path_state_rng_1D_for_decision(
-        KernelGlobals *kg,
-        const ccl_addr_space PathState *state,
-        int dimension)
-{
-	/* The rng_offset is not increased for transparent bounces. if we do then
-	 * fully transparent objects can become subtly visible by the different
-	 * sampling patterns used where the transparent object is.
-	 *
-	 * however for some random numbers that will determine if we next bounce
-	 * is transparent we do need to increase the offset to avoid always making
-	 * the same decision. */
-	const int rng_offset = state->rng_offset + state->transparent_bounce * PRNG_BOUNCE_NUM;
-	return path_rng_1D(kg,
-	                   state->rng_hash,
-	                   state->sample, state->num_samples,
-	                   rng_offset + dimension);
-}
-
 ccl_device_inline void path_state_rng_2D(KernelGlobals *kg,
                                          const ccl_addr_space PathState *state,
                                          int dimension,
@@ -232,22 +213,6 @@ ccl_device_inline float path_branched_rng_1D(
 	                   state->rng_offset + dimension);
 }
 
-ccl_device_inline float path_branched_rng_1D_for_decision(
-        KernelGlobals *kg,
-        uint rng_hash,
-        const ccl_addr_space PathState *state,
-        int branch,
-        int num_branches,
-        int dimension)
-{
-	const int rng_offset = state->rng_offset + state->transparent_bounce * PRNG_BOUNCE_NUM;
-	return path_rng_1D(kg,
-	                   rng_hash,
-	                   state->sample * num_branches + branch,
-	                   state->num_samples * num_branches,
-	                   rng_offset + dimension);
-}
-
 ccl_device_inline void path_branched_rng_2D(
         KernelGlobals *kg,
         uint rng_hash,
@@ -273,7 +238,7 @@ ccl_device_inline float path_state_rng_light_termination(
         const ccl_addr_space PathState *state)
 {
 	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
-		return path_state_rng_1D_for_decision(kg, state, PRNG_LIGHT_TERMINATE);
+		return path_state_rng_1D(kg, state, PRNG_LIGHT_TERMINATE);
 	}
 	return 0.0f;
 }
@@ -286,12 +251,12 @@ ccl_device_inline float path_branched_rng_light_termination(
         int num_branches)
 {
 	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
-		return path_branched_rng_1D_for_decision(kg,
-		                                         rng_hash,
-		                                         state,
-		                                         branch,
-		                                         num_branches,
-		                                         PRNG_LIGHT_TERMINATE);
+		return path_branched_rng_1D(kg,
+		                            rng_hash,
+		                            state,
+		                            branch,
+		                            num_branches,
+		                            PRNG_LIGHT_TERMINATE);
 	}
 	return 0.0f;
 }
diff --git a/intern/cycles/kernel/kernel_volume.h b/intern/cycles/kernel/kernel_volume.h
index d8e8e192ab2..bdaba2e2e4b 100644
--- a/intern/cycles/kernel/kernel_volume.h
+++ b/intern/cycles/kernel/kernel_volume.h
@@ -379,13 +379,13 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_homogeneous(
 
 		/* pick random color channel, we use the Veach one-sample
 		 * model with balance heuristic for the channels */
-		float rphase = path_state_rng_1D_for_decision(kg, state, PRNG_PHASE);
+		float rphase = path_state_rng_1D(kg, state, PRNG_PHASE);
 		int channel = (int)(rphase*3.0f);
 		sd->randb_closure = rphase*3.0f - channel;
 
 		/* decide if we will hit or miss */
 		bool scatter = true;
-		float xi = path_state_rng_1D_for_decision(kg, state, PRNG_SCATTER_DISTANCE);
+		float xi = path_state_rng_1D(kg, state, PRNG_SCATTER_DISTANCE);
 
 		if(probalistic_scatter) {
 			float sample_sigma_t = kernel_volume_channel_get(sigma_t, channel);
@@ -483,8 +483,8 @@ ccl_device VolumeIntegrateResult kernel_volume_integrate_heterogeneous_distance(
 
 	/* pick random color channel, we use the Veach one-sample
 	 * model with balance heuristic for the channels */
-	float xi = path_state_rng_1D_for_decision(kg, state, PRNG_SCATTER_DISTANCE);
-	float rphase = path_state_rng_1D_for_decision(kg, state, PRNG_PHASE);
+	float xi = path_state_rng_1D(kg, state, PRNG_SCATTER_DISTANCE);
+	float rphase = path_state_rng_1D(kg, state, PRNG_PHASE);
 	int channel = (int)(rphase*3.0f);
 	sd->randb_closure = rphase*3.0f - channel;
 	bool has_scatter = false;
diff --git a/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
index 9036b1e473d..4d9e08becc4 100644
--- a/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
+++ b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
@@ -140,7 +140,7 @@ ccl_device void kernel_holdout_emission_blurring_pathtermination_ao(
 			kernel_split_path_end(kg, ray_index);
 		}
 		else if(probability < 1.0f) {
-			float terminate = path_state_rng_1D_for_decision(kg, state, PRNG_TERMINATE);
+			float terminate = path_state_rng_1D(kg, state, PRNG_TERMINATE);
 			if(terminate >= probability) {
 				kernel_split_path_end(kg, ray_index);
 			}
diff --git a/intern/cycles/kernel/split/kernel_shader_eval.h b/intern/cycles/kernel/split/kernel_shader_eval.h
index eac29dcd0d1..20bd211837e 100644
--- a/intern/cycles/kernel/split/kernel_shader_eval.h
+++ b/intern/cycles/kernel/split/kernel_shader_eval.h
@@ -51,13 +51,13 @@ ccl_device void kernel_shader_eval(KernelGlobals *kg)
 		ccl_global PathState *state = &kernel_split_state.path_state[ray_index];
 
 #ifndef __BRANCHED_PATH__
-		float rbsdf = path_state_rng_1D_for_decision(kg, state, PRNG_BSDF);
+		float rbsdf = path_state_rng_1D(kg, state, PRNG_BSDF);
 		shader_eval_surface(kg, &kernel_split_state.sd[ray_index], state, rbsdf, state->flag);
 #else
 		float rbsdf = 0.0f;
 
 		if(!kernel_data.integrator.branched || IS_FLAG(ray_state, ray_index, RAY_BRANCHED_INDIRECT)) {
-			rbsdf = path_state_rng_1D_for_decision(kg, state, PRNG_BSDF);
+			rbsdf = path_state_rng_1D(kg, state, PRNG_BSDF);
 
 		}