Implement additional modes for Shrinkwrap to a surface.

In addition to the original map to surface and Keep Above Surface,
add modes that only affect vertices that are inside or outside
the object. This is inspired by the Limit Distance constraint,
and can be useful for crude collision detection in rigs.

The inside/outside test works based on face normals and may not be
completely reliable near 90 degree or sharper angles in the target.

Reviewers: campbellbarton, mont29

Differential Revision: https://developer.blender.org/D3717

3 files changed, 31 insertions, 5 deletions

diff --git a/source/blender/makesrna/RNA_enum_types.h b/source/blender/makesrna/RNA_enum_types.h
index 56b82c6c2f9..935af5c8bbd 100644
--- a/source/blender/makesrna/RNA_enum_types.h
+++ b/source/blender/makesrna/RNA_enum_types.h
@@ -72,6 +72,7 @@ extern const EnumPropertyItem rna_enum_object_shaderfx_type_items[];
 
 extern const EnumPropertyItem rna_enum_modifier_triangulate_quad_method_items[];
 extern const EnumPropertyItem rna_enum_modifier_triangulate_ngon_method_items[];
+extern const EnumPropertyItem rna_enum_modifier_shrinkwrap_mode_items[];
 
 extern const EnumPropertyItem rna_enum_image_type_items[];
 extern const EnumPropertyItem rna_enum_image_color_mode_items[];
diff --git a/source/blender/makesrna/intern/rna_constraint.c b/source/blender/makesrna/intern/rna_constraint.c
index 52c6bc105fd..39966983a8a 100644
--- a/source/blender/makesrna/intern/rna_constraint.c
+++ b/source/blender/makesrna/intern/rna_constraint.c
@@ -1934,6 +1934,12 @@ static void rna_def_constraint_shrinkwrap(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Shrinkwrap Type", "Select type of shrinkwrap algorithm for target position");
 	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
 
+	prop = RNA_def_property(srna, "wrap_mode", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "shrinkMode");
+	RNA_def_property_enum_items(prop, rna_enum_modifier_shrinkwrap_mode_items);
+	RNA_def_property_ui_text(prop, "Snap Mode", "Select how to constrain the object to the target surface");
+	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+
 	prop = RNA_def_property(srna, "distance", PROP_FLOAT, PROP_DISTANCE);
 	RNA_def_property_float_sdna(prop, NULL, "dist");
 	RNA_def_property_range(prop, 0.0f, FLT_MAX);
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 2b0f22eb8fc..1755a37016a 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -140,6 +140,24 @@ const EnumPropertyItem rna_enum_modifier_triangulate_ngon_method_items[] = {
 	{0, NULL, 0, NULL, NULL}
 };
 
+const EnumPropertyItem rna_enum_modifier_shrinkwrap_mode_items[] = {
+	{MOD_SHRINKWRAP_ON_SURFACE, "ON_SURFACE", 0, "On Surface",
+	                            "The point is constrained to the surface of the target object, "
+	                            "with distance offset towards the original point location"},
+	{MOD_SHRINKWRAP_INSIDE, "INSIDE", 0, "Inside",
+	                        "The point is constrained to be inside the target object"},
+	{MOD_SHRINKWRAP_OUTSIDE, "OUTSIDE", 0, "Outside",
+	                         "The point is constrained to be outside the target object"},
+	{MOD_SHRINKWRAP_OUTSIDE_SURFACE, "OUTSIDE_SURFACE", 0, "Outside Surface",
+	                                 "The point is constrained to the surface of the target object, "
+	                                 "with distance offset always to the outside, towards or away from the original location"},
+	{MOD_SHRINKWRAP_ABOVE_SURFACE, "ABOVE_SURFACE", 0, "Above Surface",
+	                               "The point is constrained to the surface of the target object, "
+	                               "with distance offset applied exactly along the target normal"},
+	{0, NULL, 0, NULL, NULL}
+};
+
+
 #ifndef RNA_RUNTIME
 /* use eWarp_Falloff_*** & eHook_Falloff_***, they're in sync */
 static const EnumPropertyItem modifier_warp_falloff_items[] = {
@@ -3173,6 +3191,12 @@ static void rna_def_modifier_shrinkwrap(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Mode", "");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");
 
+	prop = RNA_def_property(srna, "wrap_mode", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "shrinkMode");
+	RNA_def_property_enum_items(prop, rna_enum_modifier_shrinkwrap_mode_items);
+	RNA_def_property_ui_text(prop, "Snap Mode", "Select how vertices are constrained to the target surface");
+	RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
 	prop = RNA_def_property(srna, "cull_face", PROP_ENUM, PROP_NONE);
 	RNA_def_property_enum_sdna(prop, NULL, "shrinkOpts");
 	RNA_def_property_enum_items(prop, shrink_face_cull_items);
@@ -3249,11 +3273,6 @@ static void rna_def_modifier_shrinkwrap(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Positive", "Allow vertices to move in the positive direction of axis");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");
 
-	prop = RNA_def_property(srna, "use_keep_above_surface", PROP_BOOLEAN, PROP_NONE);
-	RNA_def_property_boolean_sdna(prop, NULL, "shrinkOpts", MOD_SHRINKWRAP_KEEP_ABOVE_SURFACE);
-	RNA_def_property_ui_text(prop, "Keep Above Surface", "");
-	RNA_def_property_update(prop, 0, "rna_Modifier_update");
-
 	prop = RNA_def_property(srna, "invert_vertex_group", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "shrinkOpts", MOD_SHRINKWRAP_INVERT_VGROUP);
 	RNA_def_property_ui_text(prop, "Invert", "Invert vertex group influence");