Cycles: add random walk subsurface scattering to Principled BSDF.

Differential Revision: https://developer.blender.org/D3054

3 files changed, 25 insertions, 3 deletions

diff --git a/source/blender/editors/space_node/drawnode.c b/source/blender/editors/space_node/drawnode.c
index eccf3c057d4..9d873795eaf 100644
--- a/source/blender/editors/space_node/drawnode.c
+++ b/source/blender/editors/space_node/drawnode.c
@@ -1082,6 +1082,12 @@ static void node_shader_buts_glossy(uiLayout *layout, bContext *UNUSED(C), Point
 	uiItemR(layout, ptr, "distribution", 0, "", ICON_NONE);
 }
 
+static void node_shader_buts_principled(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
+{
+	uiItemR(layout, ptr, "distribution", 0, "", ICON_NONE);
+	uiItemR(layout, ptr, "subsurface_method", 0, "", ICON_NONE);
+}
+
 static void node_shader_buts_anisotropic(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
 	uiItemR(layout, ptr, "distribution", 0, "", ICON_NONE);
@@ -1254,9 +1260,11 @@ static void node_shader_set_butfunc(bNodeType *ntype)
 		case SH_NODE_BSDF_GLOSSY:
 		case SH_NODE_BSDF_GLASS:
 		case SH_NODE_BSDF_REFRACTION:
-		case SH_NODE_BSDF_PRINCIPLED:
 			ntype->draw_buttons = node_shader_buts_glossy;
 			break;
+		case SH_NODE_BSDF_PRINCIPLED:
+			ntype->draw_buttons = node_shader_buts_principled;
+			break;
 		case SH_NODE_BSDF_ANISOTROPIC:
 			ntype->draw_buttons = node_shader_buts_anisotropic;
 			break;
diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index bbe78d43f50..ccd16e16760 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -3293,11 +3293,18 @@ static const EnumPropertyItem node_script_mode_items[] = {
 };
 
 static const EnumPropertyItem node_principled_distribution_items[] = {
-	{ SHD_GLOSSY_GGX, "GGX", 0, "GGX", "" },
-	{ SHD_GLOSSY_MULTI_GGX, "MULTI_GGX", 0, "Multiscatter GGX", "" },
+	{SHD_GLOSSY_GGX, "GGX", 0, "GGX", ""},
+	{SHD_GLOSSY_MULTI_GGX, "MULTI_GGX", 0, "Multiscatter GGX", ""},
+	{0, NULL, 0, NULL, NULL}
+};
+
+static const EnumPropertyItem node_subsurface_method_items[] = {
+	{SHD_SUBSURFACE_BURLEY, "BURLEY", 0, "Christensen-Burley", "Approximation to physically based volume scattering"},
+	{SHD_SUBSURFACE_RANDOM_WALK, "RANDOM_WALK", 0, "Random Walk", "Volumetric approximation to physically based volume scattering"},
 	{ 0, NULL, 0, NULL, NULL }
 };
 
+
 /* -- Common nodes ---------------------------------------------------------- */
 
 static void def_group_input(StructRNA *srna)
@@ -4241,6 +4248,12 @@ static void def_principled(StructRNA *srna)
 	RNA_def_property_enum_items(prop, node_principled_distribution_items);
 	RNA_def_property_ui_text(prop, "Distribution", "");
 	RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_ShaderNodePrincipled_update");
+
+	prop = RNA_def_property(srna, "subsurface_method", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "custom2");
+	RNA_def_property_enum_items(prop, node_subsurface_method_items);
+	RNA_def_property_ui_text(prop, "Subsurface Method", "Method for rendering subsurface scattering");
+	RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_ShaderNodePrincipled_update");
 }
 
 static void def_refraction(StructRNA *srna)
diff --git a/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c b/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
index e0330d110ca..cd83139dcaa 100644
--- a/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
+++ b/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
@@ -61,6 +61,7 @@ static bNodeSocketTemplate sh_node_bsdf_principled_out[] = {
 static void node_shader_init_principled(bNodeTree *UNUSED(ntree), bNode *node)
 {
 	node->custom1 = SHD_GLOSSY_MULTI_GGX;
+	node->custom2 = SHD_SUBSURFACE_BURLEY;
 }
 
 static int node_shader_gpu_bsdf_principled(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)