Change in behavior to shrinkwrap modifier's offset value with negative enabled.

- negative ray casts would invert the offset direction.
  this meant if positive and negative were enabled at once and the mesh was slightly inside & outside the object it wrapped,
  the offset would be applied in opposite directions.
  This way the offset is always along the vertex normal.

- allow negative offset from RNA, could be useful and no benefit to disable.

2 files changed, 4 insertions, 9 deletions

diff --git a/source/blender/blenkernel/intern/shrinkwrap.c b/source/blender/blenkernel/intern/shrinkwrap.c
index 75a955a09a9..48d9a4e0dee 100644
--- a/source/blender/blenkernel/intern/shrinkwrap.c
+++ b/source/blender/blenkernel/intern/shrinkwrap.c
@@ -378,9 +378,6 @@ static void shrinkwrap_calc_normal_projection(ShrinkwrapCalcData *calc)
 					normal_projection_project_vertex(0, tmp_co, tmp_no, &local2aux, auxData.tree, &hit, auxData.raycast_callback, &auxData);
 
 				normal_projection_project_vertex(calc->smd->shrinkOpts, tmp_co, tmp_no, &calc->local2target, treeData.tree, &hit, treeData.raycast_callback, &treeData);
-
-				if(hit.index != -1)
-					madd_v3_v3v3fl(hit.co, hit.co, tmp_no, -calc->keepDist);
 			}
 
 			//Project over negative direction of axis
@@ -393,14 +390,12 @@ static void shrinkwrap_calc_normal_projection(ShrinkwrapCalcData *calc)
 					normal_projection_project_vertex(0, tmp_co, inv_no, &local2aux, auxData.tree, &hit, auxData.raycast_callback, &auxData);
 
 				normal_projection_project_vertex(calc->smd->shrinkOpts, tmp_co, inv_no, &calc->local2target, treeData.tree, &hit, treeData.raycast_callback, &treeData);
-
-				if(hit.index != -1)
-					madd_v3_v3v3fl(hit.co, hit.co, tmp_no, calc->keepDist);
 			}
 
 
 			if(hit.index != -1)
 			{
+				madd_v3_v3v3fl(hit.co, hit.co, tmp_no, calc->keepDist);
 				interp_v3_v3v3(co, co, hit.co, weight);
 			}
 		}
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 33a6856db73..15da48a82d4 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -1900,11 +1900,11 @@ static void rna_def_modifier_shrinkwrap(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Vertex Group", "Vertex group name");
 	RNA_def_property_string_funcs(prop, NULL, NULL, "rna_ShrinkwrapModifier_vgroup_set");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");
-	
+
 	prop= RNA_def_property(srna, "offset", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_float_sdna(prop, NULL, "keepDist");
-	RNA_def_property_range(prop, 0, FLT_MAX);
-	RNA_def_property_ui_range(prop, 0, 100, 1, 2);
+	RNA_def_property_range(prop, -FLT_MAX, FLT_MAX);
+	RNA_def_property_ui_range(prop, -100, 100, 1, 2);
 	RNA_def_property_ui_text(prop, "Offset", "Distance to keep from the target");
 	RNA_def_property_update(prop, 0, "rna_Modifier_update");