Bugfix #25301

Material Node trees:
SSS wasn't displaying in Nodes.

Implementation notes:
- Currently copying local data for preview render, only copies
  the base material. Node materials are re-used.
- This causes data to be in 2 "main" databases... complex.
- To make it work for preview, I had to add another loop in the
  SSS code that checks the original Main dbase. That's marked
  as warning in code to be fixed up.

Another bug:
- Material properties "SSS presets" copied settings to the
  active material, not to the displayed one. Added RNA call 
  to retrieve this from Objects.

(Next commit will fix preset scripts)

3 files changed, 60 insertions, 1 deletions

diff --git a/source/blender/editors/render/render_preview.c b/source/blender/editors/render/render_preview.c
index f8c8faffc88..2eac7c20350 100644
--- a/source/blender/editors/render/render_preview.c
+++ b/source/blender/editors/render/render_preview.c
@@ -49,6 +49,7 @@
 #include "DNA_world_types.h"
 #include "DNA_camera_types.h"
 #include "DNA_material_types.h"
+#include "DNA_node_types.h"
 #include "DNA_object_types.h"
 #include "DNA_lamp_types.h"
 #include "DNA_space_types.h"
@@ -309,6 +310,32 @@ static Object *find_object(ListBase *lb, const char *name)
 	return ob;
 }
 
+static int preview_mat_has_sss(Material *mat, bNodeTree *ntree)
+{
+	if(mat) {
+		if(mat->sss_flag & MA_DIFF_SSS)
+			return 1;
+		if(mat->nodetree)
+			if( preview_mat_has_sss(NULL, mat->nodetree))
+				return 1;
+	}
+	else if(ntree) {
+		bNode *node;
+		for(node= ntree->nodes.first; node; node= node->next) {
+			if(node->type==NODE_GROUP && node->id) {
+				if( preview_mat_has_sss(NULL, (bNodeTree *)node->id))
+					return 1;
+			}
+			else if(node->id && ELEM(node->type, SH_NODE_MATERIAL, SH_NODE_MATERIAL_EXT)) {
+				mat= (Material *)node->id;
+				if(mat->sss_flag & MA_DIFF_SSS)
+					return 1;
+			}
+		}
+	}
+	return 0;
+}
+
 /* call this with a pointer to initialize preview scene */
 /* call this with NULL to restore assigned ID pointers in preview scene */
 static Scene *preview_prepare_scene(Scene *scene, ID *id, int id_type, ShaderPreview *sp)
@@ -361,7 +388,7 @@ static Scene *preview_prepare_scene(Scene *scene, ID *id, int id_type, ShaderPre
 					sce->r.mode |= R_RAYTRACE;
 				if((mat->mode_l & MA_RAYTRANSP) && (mat->mode_l & MA_TRANSP))
 					sce->r.mode |= R_RAYTRACE;
-				if(mat->sss_flag & MA_DIFF_SSS)
+				if(preview_mat_has_sss(mat, NULL))
 					sce->r.mode |= R_SSS;
 				
 				/* turn off fake shadows if needed */
diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index 2c5cddca77f..6031d3e29d9 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -587,12 +587,29 @@ static void rna_Object_active_material_index_range(PointerRNA *ptr, int *min, in
 	*max= MAX2(ob->totcol-1, 0);
 }
 
+/* returns active base material */
 static PointerRNA rna_Object_active_material_get(PointerRNA *ptr)
 {
 	Object *ob= (Object*)ptr->id.data;
 	Material *ma;
+	
+	ma= (ob->totcol)? give_current_material(ob, ob->actcol): NULL;
+	return rna_pointer_inherit_refine(ptr, &RNA_Material, ma);
+}
 
+/* returns (optional) active node material in base material */
+static PointerRNA rna_Object_active_node_material_get(PointerRNA *ptr)
+{
+	Object *ob= (Object*)ptr->id.data;
+	Material *ma;
+	
 	ma= (ob->totcol)? give_current_material(ob, ob->actcol): NULL;
+	if(ma) {
+		Material *manode= give_node_material(ma);
+		if(manode)
+			return rna_pointer_inherit_refine(ptr, &RNA_Material, manode);
+	}
+	
 	return rna_pointer_inherit_refine(ptr, &RNA_Material, ma);
 }
 
@@ -1777,6 +1794,13 @@ static void rna_def_object(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Active Material", "Active material being displayed");
 	RNA_def_property_update(prop, NC_OBJECT|ND_DRAW, "rna_MaterialSlot_update");
 
+	prop= RNA_def_property(srna, "active_node_material", PROP_POINTER, PROP_NONE);
+	RNA_def_property_struct_type(prop, "Material");
+	RNA_def_property_pointer_funcs(prop, "rna_Object_active_node_material_get", NULL, NULL, NULL);
+	RNA_def_property_ui_text(prop, "Active Material", "Active (node) material being displayed");
+	RNA_def_property_update(prop, NC_OBJECT|ND_DRAW, NULL);
+	
+	
 	prop= RNA_def_property(srna, "active_material_index", PROP_INT, PROP_UNSIGNED);
 	RNA_def_property_int_sdna(prop, NULL, "actcol");
 	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
diff --git a/source/blender/render/intern/source/sss.c b/source/blender/render/intern/source/sss.c
index 993e0aeb9c3..4bccb46d3d8 100644
--- a/source/blender/render/intern/source/sss.c
+++ b/source/blender/render/intern/source/sss.c
@@ -997,6 +997,14 @@ void make_sss_tree(Render *re)
 		if(mat->id.us && (mat->flag & MA_IS_USED) && (mat->sss_flag & MA_DIFF_SSS))
 			sss_create_tree_mat(re, mat);
 	
+	/* XXX preview exception */
+	/* localizing preview render data is not fun for node trees :( */
+	if(re->main!=G.main) {
+		for(mat= G.main->mat.first; mat; mat= mat->id.next)
+			if(mat->id.us && (mat->flag & MA_IS_USED) && (mat->sss_flag & MA_DIFF_SSS))
+				sss_create_tree_mat(re, mat);
+	}
+	
 }
 
 void free_sss(Render *re)