Init

space_view3d_align_faces.py

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+import bpy
+import math
+from mathutils import Vector
+from functools import reduce
+
+bl_info = {
+    "name": "Align by faces",
+    "author": "Tom Rethaller",
+    "version": (0,2,2),
+    "blender": (2, 65, 0),
+    "description": "Align two objects by their active faces",
+    "warning": "",
+    "category": "3D View"}
+
+def get_ortho(a,b,c):
+    if c != 0.0 and -a != b:
+        return [-b-c, a,a]
+    else:
+        return [c,c,-a-b]
+
+def clamp(v,min,max):
+    if v < min:
+        return min
+    if v > max:
+        return max
+    return v
+
+def align_faces(from_obj, to_obj):
+    fpolys = from_obj.data.polygons
+    tpolys = to_obj.data.polygons
+    fpoly = fpolys[fpolys.active]
+    tpoly = tpolys[tpolys.active]
+
+    to_obj.rotation_mode = 'QUATERNION'
+    tnorm = to_obj.rotation_quaternion * tpoly.normal
+
+    fnorm = fpoly.normal
+    axis = fnorm.cross(tnorm)
+    dot = fnorm.normalized().dot(tnorm.normalized())
+    dot = clamp(dot, -1.0, 1.0)
+
+    # Parallel faces need a new rotation vactor
+    if axis.length < 1.0e-8:
+        axis = Vector(get_ortho(fnorm.x, fnorm.y, fnorm.z))
+
+    from_obj.rotation_mode = 'AXIS_ANGLE'
+    from_obj.rotation_axis_angle = [math.acos(dot) + math.pi, axis[0],axis[1],axis[2]]
+    bpy.context.scene.update()  
+
+    # Move from_obj so that faces match
+    fvertices = [from_obj.data.vertices[i].co for i in fpoly.vertices]
+    tvertices = [to_obj.data.vertices[i].co for i in tpoly.vertices]
+
+    fbary = from_obj.matrix_world * (reduce(Vector.__add__, fvertices) / len(fvertices))
+    tbary = to_obj.matrix_world * (reduce(Vector.__add__, tvertices) / len(tvertices))
+
+    from_obj.location = tbary - (fbary - from_obj.location)
+
+
+class OBJECT_OT_AlignByFaces(bpy.types.Operator):
+    bl_label = "Align by faces"
+    bl_description= "Align two objects by their active faces"
+    bl_idname = "object.align_by_faces"
+
+    @classmethod
+    def poll(cls, context):
+        if not len(context.selected_objects) is 2:
+            return False
+        for obj in context.selected_objects:
+            if obj.type != 'MESH':
+                return False
+        return True
+
+    def execute(self, context):
+        objs_to_move = [o for o in context.selected_objects if o != context.active_object]
+        for o in objs_to_move:
+        	align_faces(o, context.active_object)
+        return {'FINISHED'}
+
+def register():
+    bpy.utils.register_module(__name__)
+
+def unregister():
+    bpy.utils.unregister_module(__name__)
+