Cycles: change Ambient Occlusion shader to output colors.

This means the shader can now be used for procedural texturing. New
settings on the node are Samples, Inside, Local Only and Distance.

Original patch by Lukas with further changes by Brecht.

Differential Revision: https://developer.blender.org/D3479

4 files changed, 122 insertions, 24 deletions

diff --git a/intern/cycles/kernel/svm/svm.h b/intern/cycles/kernel/svm/svm.h
index ce2affe96c8..10d5fe0e42b 100644
--- a/intern/cycles/kernel/svm/svm.h
+++ b/intern/cycles/kernel/svm/svm.h
@@ -144,6 +144,7 @@ CCL_NAMESPACE_END
 #include "kernel/svm/svm_color_util.h"
 #include "kernel/svm/svm_math_util.h"
 
+#include "kernel/svm/svm_ao.h"
 #include "kernel/svm/svm_attribute.h"
 #include "kernel/svm/svm_gradient.h"
 #include "kernel/svm/svm_blackbody.h"
@@ -324,9 +325,6 @@ ccl_device_noinline void svm_eval_nodes(KernelGlobals *kg, ShaderData *sd, ccl_a
 			case NODE_CLOSURE_HOLDOUT:
 				svm_node_closure_holdout(sd, stack, node);
 				break;
-			case NODE_CLOSURE_AMBIENT_OCCLUSION:
-				svm_node_closure_ambient_occlusion(sd, stack, node);
-				break;
 			case NODE_FRESNEL:
 				svm_node_fresnel(sd, stack, node.y, node.z, node.w);
 				break;
@@ -480,6 +478,9 @@ ccl_device_noinline void svm_eval_nodes(KernelGlobals *kg, ShaderData *sd, ccl_a
 			case NODE_BEVEL:
 				svm_node_bevel(kg, sd, state, stack, node);
 				break;
+			case NODE_AMBIENT_OCCLUSION:
+				svm_node_ao(kg, sd, state, stack, node);
+				break;
 #  endif  /* __SHADER_RAYTRACE__ */
 #endif  /* NODES_GROUP(NODE_GROUP_LEVEL_3) */
 			case NODE_END:
diff --git a/intern/cycles/kernel/svm/svm_ao.h b/intern/cycles/kernel/svm/svm_ao.h
new file mode 100644
index 00000000000..3f761627e2c
--- /dev/null
+++ b/intern/cycles/kernel/svm/svm_ao.h
@@ -0,0 +1,111 @@
+/*
+* Copyright 2011-2018 Blender Foundation
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+CCL_NAMESPACE_BEGIN
+
+ccl_device_noinline float svm_ao(KernelGlobals *kg,
+                                 ShaderData *sd,
+                                 float3 N,
+                                 ccl_addr_space PathState *state,
+                                 float max_dist,
+                                 int num_samples,
+                                 int flags)
+{
+	if(flags & NODE_AO_GLOBAL_RADIUS) {
+		max_dist = kernel_data.background.ao_distance;
+	}
+
+	/* Early out if no sampling needed. */
+	if(max_dist <= 0.0f || num_samples < 1 || sd->object == OBJECT_NONE) {
+		return 0.0f;
+	}
+
+	if(flags & NODE_AO_INSIDE) {
+		N = -N;
+	}
+
+	float3 T, B;
+	make_orthonormals(N, &T, &B);
+
+	int unoccluded = 0;
+	for(int sample = 0; sample < num_samples; sample++) {
+		float disk_u, disk_v;
+		path_branched_rng_2D(kg, state->rng_hash, state, sample, num_samples,
+		                     PRNG_BEVEL_U, &disk_u, &disk_v);
+
+		float2 d = concentric_sample_disk(disk_u, disk_v);
+		float3 D = make_float3(d.x, d.y, safe_sqrtf(1.0f - dot(d, d)));
+
+		/* Create ray. */
+		Ray ray;
+		ray.P = ray_offset(sd->P, N);
+		ray.D = D.x*T + D.y*B + D.z*N;
+		ray.t = max_dist;
+		ray.time = sd->time;
+
+		if(flags & NODE_AO_ONLY_LOCAL) {
+			if(!scene_intersect_local(kg,
+			                          ray,
+			                          NULL,
+			                          sd->object,
+			                          NULL,
+			                          0)) {
+				unoccluded++;
+			}
+		}
+		else {
+			Intersection isect;
+			if(!scene_intersect(kg,
+			                    ray,
+			                    PATH_RAY_SHADOW_OPAQUE,
+			                    &isect,
+			                    NULL,
+			                    0.0f, 0.0f)) {
+				unoccluded++;
+			}
+		}
+	}
+
+	return ((float) unoccluded) / num_samples;
+}
+
+ccl_device void svm_node_ao(KernelGlobals *kg,
+                            ShaderData *sd,
+                            ccl_addr_space PathState *state,
+                            float *stack,
+                            uint4 node)
+{
+	uint flags, dist_offset, normal_offset, out_ao_offset;
+	decode_node_uchar4(node.y, &flags, &dist_offset, &normal_offset, &out_ao_offset);
+
+	uint color_offset, out_color_offset, samples;
+	decode_node_uchar4(node.z, &color_offset, &out_color_offset, &samples, NULL);
+
+	float dist = stack_load_float_default(stack, dist_offset, node.w);
+	float3 normal = stack_valid(normal_offset)? stack_load_float3(stack, normal_offset): sd->N;
+	float ao = svm_ao(kg, sd, normal, state, dist, samples, flags);
+
+	if (stack_valid(out_ao_offset)) {
+		stack_store_float(stack, out_ao_offset, ao);
+	}
+
+	if (stack_valid(out_color_offset)) {
+		float3 color = stack_load_float3(stack, color_offset);
+		stack_store_float3(stack, out_color_offset, ao * color);
+	}
+}
+
+CCL_NAMESPACE_END
diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index 76464e37c66..f5b316c67da 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -996,24 +996,6 @@ ccl_device void svm_node_closure_holdout(ShaderData *sd, float *stack, uint4 nod
 	sd->flag |= SD_HOLDOUT;
 }
 
-ccl_device void svm_node_closure_ambient_occlusion(ShaderData *sd, float *stack, uint4 node)
-{
-	uint mix_weight_offset = node.y;
-
-	if(stack_valid(mix_weight_offset)) {
-		float mix_weight = stack_load_float(stack, mix_weight_offset);
-
-		if(mix_weight == 0.0f)
-			return;
-
-		closure_alloc(sd, sizeof(ShaderClosure), CLOSURE_AMBIENT_OCCLUSION_ID, sd->svm_closure_weight * mix_weight);
-	}
-	else
-		closure_alloc(sd, sizeof(ShaderClosure), CLOSURE_AMBIENT_OCCLUSION_ID, sd->svm_closure_weight);
-
-	sd->flag |= SD_AO;
-}
-
 /* Closure Nodes */
 
 ccl_device_inline void svm_node_closure_store_weight(ShaderData *sd, float3 weight)
diff --git a/intern/cycles/kernel/svm/svm_types.h b/intern/cycles/kernel/svm/svm_types.h
index ac24d23ecd2..54db18cd7bb 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -124,7 +124,7 @@ typedef enum ShaderNodeType {
 	NODE_PARTICLE_INFO,
 	NODE_TEX_BRICK,
 	NODE_CLOSURE_SET_NORMAL,
-	NODE_CLOSURE_AMBIENT_OCCLUSION,
+	NODE_AMBIENT_OCCLUSION,
 	NODE_TANGENT,
 	NODE_NORMAL_MAP,
 	NODE_HAIR_INFO,
@@ -386,6 +386,12 @@ typedef enum NodeTexVoxelSpace {
 	NODE_TEX_VOXEL_SPACE_WORLD  = 1,
 } NodeTexVoxelSpace;
 
+typedef enum NodeAO {
+	NODE_AO_ONLY_LOCAL = (1 << 0),
+	NODE_AO_INSIDE = (1 << 1),
+	NODE_AO_GLOBAL_RADIUS = (1 << 2),
+} NodeAO;
+
 typedef enum ShaderType {
 	SHADER_TYPE_SURFACE,
 	SHADER_TYPE_VOLUME,
@@ -456,7 +462,6 @@ typedef enum ClosureType {
 
 	/* Other */
 	CLOSURE_HOLDOUT_ID,
-	CLOSURE_AMBIENT_OCCLUSION_ID,
 
 	/* Volume */
 	CLOSURE_VOLUME_ID,
@@ -491,7 +496,6 @@ typedef enum ClosureType {
 #define CLOSURE_IS_VOLUME_SCATTER(type) (type == CLOSURE_VOLUME_HENYEY_GREENSTEIN_ID)
 #define CLOSURE_IS_VOLUME_ABSORPTION(type) (type == CLOSURE_VOLUME_ABSORPTION_ID)
 #define CLOSURE_IS_HOLDOUT(type) (type == CLOSURE_HOLDOUT_ID)
-#define CLOSURE_IS_AMBIENT_OCCLUSION(type) (type == CLOSURE_AMBIENT_OCCLUSION_ID)
 #define CLOSURE_IS_PHASE(type) (type == CLOSURE_VOLUME_HENYEY_GREENSTEIN_ID)
 #define CLOSURE_IS_GLASS(type) (type >= CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID && type <= CLOSURE_BSDF_SHARP_GLASS_ID)
 #define CLOSURE_IS_PRINCIPLED(type) (type == CLOSURE_BSDF_PRINCIPLED_ID)