[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [51458] trunk/blender/source/blender: Add option to set object origin to the center of mass

[Sergej Reich]

Revision: 51458
          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=51458
Author:   sergof
Date:     2012-10-20 16:48:54 +0000 (Sat, 20 Oct 2012)
Log Message:
-----------
Add option to set object origin to the center of mass

This uses the weighted average of polygon centroids based on area
It work well in most cases but will be slightly wrong when polygons have 
many vertices.

Modified Paths:
--------------
    trunk/blender/source/blender/blenkernel/BKE_mesh.h
    trunk/blender/source/blender/blenkernel/intern/mesh.c
    trunk/blender/source/blender/editors/object/object_transform.c

Modified: trunk/blender/source/blender/blenkernel/BKE_mesh.h
===================================================================
--- trunk/blender/source/blender/blenkernel/BKE_mesh.h	2012-10-20 16:48:48 UTC (rev 51457)
+++ trunk/blender/source/blender/blenkernel/BKE_mesh.h	2012-10-20 16:48:54 UTC (rev 51458)
@@ -292,6 +292,7 @@
 int BKE_mesh_minmax(struct Mesh *me, float r_min[3], float r_max[3]);
 int BKE_mesh_center_median(struct Mesh *me, float cent[3]);
 int BKE_mesh_center_bounds(struct Mesh *me, float cent[3]);
+int BKE_mesh_center_centroid(struct Mesh *me, float cent[3]);
 void BKE_mesh_translate(struct Mesh *me, float offset[3], int do_keys);
 
 /* mesh_validate.c */

Modified: trunk/blender/source/blender/blenkernel/intern/mesh.c
===================================================================
--- trunk/blender/source/blender/blenkernel/intern/mesh.c	2012-10-20 16:48:48 UTC (rev 51457)
+++ trunk/blender/source/blender/blenkernel/intern/mesh.c	2012-10-20 16:48:54 UTC (rev 51458)
@@ -3175,6 +3175,32 @@
 	return 0;
 }
 
+int BKE_mesh_center_centroid(Mesh *me, float cent[3])
+{
+	int i = me->totpoly;
+	MPoly *mpoly;
+	float poly_area;
+	float total_area = 0.0f;
+	float poly_cent[3];
+	
+	zero_v3(cent);
+	
+	/* calculate a weighted average of polygon centroids */
+	for (mpoly = me->mpoly; i--; mpoly++) {
+		BKE_mesh_calc_poly_center(mpoly, me->mloop + mpoly->loopstart, me->mvert, poly_cent);
+		poly_area = BKE_mesh_calc_poly_area(mpoly, me->mloop + mpoly->loopstart, me->mvert, NULL);
+		
+		madd_v3_v3fl(cent, poly_cent, poly_area);
+		total_area += poly_area;
+	}
+	/* otherwise we get NAN for 0 polys */
+	if (me->totpoly) {
+		mul_v3_fl(cent, 1.0f / total_area);
+	}
+
+	return (me->totpoly != 0);
+}
+
 void BKE_mesh_translate(Mesh *me, float offset[3], int do_keys)
 {
 	int i = me->totvert;

Modified: trunk/blender/source/blender/editors/object/object_transform.c
===================================================================
--- trunk/blender/source/blender/editors/object/object_transform.c	2012-10-20 16:48:48 UTC (rev 51457)
+++ trunk/blender/source/blender/editors/object/object_transform.c	2012-10-20 16:48:54 UTC (rev 51458)
@@ -654,7 +654,8 @@
 enum {
 	GEOMETRY_TO_ORIGIN = 0,
 	ORIGIN_TO_GEOMETRY,
-	ORIGIN_TO_CURSOR
+	ORIGIN_TO_CURSOR,
+	ORIGIN_TO_CENTER_OF_MASS
 };
 
 static int object_origin_set_exec(bContext *C, wmOperator *op)
@@ -785,6 +786,7 @@
 				Mesh *me = ob->data;
 
 				if (centermode == ORIGIN_TO_CURSOR) { /* done */ }
+				else if (centermode == ORIGIN_TO_CENTER_OF_MASS) { BKE_mesh_center_centroid(me, cent); }
 				else if (around == V3D_CENTROID) { BKE_mesh_center_median(me, cent); }
 				else { BKE_mesh_center_bounds(me, cent); }
 
@@ -980,6 +982,8 @@
 		                     "Move object origin to center of object geometry"},
 		{ORIGIN_TO_CURSOR, "ORIGIN_CURSOR", 0, "Origin to 3D Cursor",
 		                   "Move object origin to position of the 3D cursor"},
+		{ORIGIN_TO_CENTER_OF_MASS, "ORIGIN_CENTER_OF_MASS", 0, "Origin to Center of Mass",
+		                           "Move object origin to the object center of mass (assuming uniform density)"},
 		{0, NULL, 0, NULL, NULL}
 	};
 	
@@ -1006,4 +1010,3 @@
 	ot->prop = RNA_def_enum(ot->srna, "type", prop_set_center_types, 0, "Type", "");
 	RNA_def_enum(ot->srna, "center", prop_set_bounds_types, V3D_CENTROID, "Center", "");
 }
-