Cycles Volume Render: work on nodes and closures.

* Henyey-Greenstein scattering closure implementation.
* Rename transparent to absorption node and isotropic to scatter node.
* Volume density is folded into the closure weights.
* OSL support for volume closures and nodes.
* This commit has no user visible changes, there is no volume render code yet.

This is work by "storm", Stuart Broadfoot, Thomas Dinges and myself.

3 files changed, 19 insertions, 14 deletions

diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index 2c6fb5deca4..dca9c3a91e5 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -77,7 +77,7 @@ ccl_device_inline ShaderClosure *svm_node_closure_get_bsdf(ShaderData *sd, float
 	float3 weight = sc->weight * mix_weight;
 	float sample_weight = fabsf(average(weight));
 
-	if(sample_weight > 1e-5f && sd->num_closure < MAX_CLOSURE) {
+	if(sample_weight > CLOSURE_WEIGHT_CUTOFF && sd->num_closure < MAX_CLOSURE) {
 		sc->weight = weight;
 		sc->sample_weight = sample_weight;
 		sd->num_closure++;
@@ -390,7 +390,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 			if(path_flag & PATH_RAY_DIFFUSE_ANCESTOR)
 				param1 = 0.0f;
 
-			if(sample_weight > 1e-5f && sd->num_closure+2 < MAX_CLOSURE) {
+			if(sample_weight > CLOSURE_WEIGHT_CUTOFF && sd->num_closure+2 < MAX_CLOSURE) {
 				/* radius * scale */
 				float3 radius = stack_load_float3(stack, data_node.z)*param1;
 				/* sharpness */
@@ -473,24 +473,25 @@ ccl_device void svm_node_closure_volume(KernelGlobals *kg, ShaderData *sd, float
 #endif
 
 	float param1 = (stack_valid(param1_offset))? stack_load_float(stack, param1_offset): __uint_as_float(node.z);
-	//float param2 = (stack_valid(param2_offset))? stack_load_float(stack, param2_offset): __uint_as_float(node.w);
+	float param2 = (stack_valid(param2_offset))? stack_load_float(stack, param2_offset): __uint_as_float(node.w);
+	float density = param1;
 
 	switch(type) {
-		case CLOSURE_VOLUME_TRANSPARENT_ID: {
-			ShaderClosure *sc = svm_node_closure_get_bsdf(sd, mix_weight);
+		case CLOSURE_VOLUME_ABSORPTION_ID: {
+			ShaderClosure *sc = svm_node_closure_get_bsdf(sd, mix_weight * density);
 
 			if(sc) {
-				float density = param1;
-				sd->flag |= volume_transparent_setup(sc, density);
+				sd->flag |= volume_absorption_setup(sc);
 			}
 			break;
 		}
-		case CLOSURE_VOLUME_ISOTROPIC_ID: {
-			ShaderClosure *sc = svm_node_closure_get_bsdf(sd, mix_weight);
+		case CLOSURE_VOLUME_HENYEY_GREENSTEIN_ID: {
+			ShaderClosure *sc = svm_node_closure_get_bsdf(sd, mix_weight * density);
 
 			if(sc) {
-				float density = param1;
-				sd->flag |= volume_isotropic_setup(sc, density);
+				float g = param2;
+				sc->data0 = g;
+				sd->flag |= volume_henyey_greenstein_setup(sc);
 			}
 			break;
 		}
diff --git a/intern/cycles/kernel/svm/svm_light_path.h b/intern/cycles/kernel/svm/svm_light_path.h
index e7afa2d2200..8968146c5e2 100644
--- a/intern/cycles/kernel/svm/svm_light_path.h
+++ b/intern/cycles/kernel/svm/svm_light_path.h
@@ -30,6 +30,7 @@ ccl_device void svm_node_light_path(ShaderData *sd, float *stack, uint type, uin
 		case NODE_LP_singular: info = (path_flag & PATH_RAY_SINGULAR)? 1.0f: 0.0f; break;
 		case NODE_LP_reflection: info = (path_flag & PATH_RAY_REFLECT)? 1.0f: 0.0f; break;
 		case NODE_LP_transmission: info = (path_flag & PATH_RAY_TRANSMIT)? 1.0f: 0.0f; break;
+		case NODE_LP_volume_scatter: info = (path_flag & PATH_RAY_VOLUME_SCATTER)? 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;
diff --git a/intern/cycles/kernel/svm/svm_types.h b/intern/cycles/kernel/svm/svm_types.h
index abd63530d63..e6df5fe17b7 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -154,6 +154,7 @@ typedef enum NodeLightPath {
 	NODE_LP_singular,
 	NODE_LP_reflection,
 	NODE_LP_transmission,
+	NODE_LP_volume_scatter,
 	NODE_LP_backfacing,
 	NODE_LP_ray_length,
 	NODE_LP_ray_depth
@@ -389,8 +390,8 @@ typedef enum ClosureType {
 
 	/* Volume */
 	CLOSURE_VOLUME_ID,
-	CLOSURE_VOLUME_TRANSPARENT_ID,
-	CLOSURE_VOLUME_ISOTROPIC_ID,
+	CLOSURE_VOLUME_ABSORPTION_ID,
+	CLOSURE_VOLUME_HENYEY_GREENSTEIN_ID,
 
 	NBUILTIN_CLOSURES
 } ClosureType;
@@ -402,12 +403,14 @@ typedef enum ClosureType {
 #define CLOSURE_IS_BSDF_TRANSMISSION(type) (type >= CLOSURE_BSDF_TRANSMISSION_ID && type <= CLOSURE_BSDF_HAIR_TRANSMISSION_ID)
 #define CLOSURE_IS_BSDF_BSSRDF(type) (type == CLOSURE_BSDF_BSSRDF_ID)
 #define CLOSURE_IS_BSSRDF(type) (type >= CLOSURE_BSSRDF_CUBIC_ID && type <= CLOSURE_BSSRDF_GAUSSIAN_ID)
-#define CLOSURE_IS_VOLUME(type) (type >= CLOSURE_VOLUME_ID && type <= CLOSURE_VOLUME_ISOTROPIC_ID)
+#define CLOSURE_IS_VOLUME(type) (type >= CLOSURE_VOLUME_ID && type <= CLOSURE_VOLUME_HENYEY_GREENSTEIN_ID)
 #define CLOSURE_IS_EMISSION(type) (type == CLOSURE_EMISSION_ID)
 #define CLOSURE_IS_HOLDOUT(type) (type == CLOSURE_HOLDOUT_ID)
 #define CLOSURE_IS_BACKGROUND(type) (type == CLOSURE_BACKGROUND_ID)
 #define CLOSURE_IS_AMBIENT_OCCLUSION(type) (type == CLOSURE_AMBIENT_OCCLUSION_ID)
 
+#define CLOSURE_WEIGHT_CUTOFF 1e-5f
+
 CCL_NAMESPACE_END
 
 #endif /*  __SVM_TYPES_H__ */