[Bf-committers] Cursor to center of mass

[Brecht Van Lommel]

Tessfaces includes both triangles and quads, it doesn't triangulate
entirely, so you'd need to handle the quads still.

Brecht.

On Wed, Nov 21, 2012 at 4:30 AM, Ummi Nom <umminom at gmail.com> wrote:
> Hi!
>
> I've written some center of mass calculations in python for closed meshes,
> but there is an issue with using tessfaces in my code; I run mesh.update
> with tessfaces=True but when I loop over mesh.tessfaces there are only 6
> faces in default scene cube so the center of mass is offset.
>
> It seems to work when the mesh is triangulated
> http://www.pasteall.org/37396/python
>
> # Code
> import mathutils
> from mathutils import *
> import bpy
>
> tess_count = 0
>
> # Handle tri as a tetrahedron with fourth point at origo
> def handleTri(v1, v2, v3):
>     global tess_count
>     tess_count = tess_count + 1
>
>     temp = (v3-v1).cross(v2-v1)
>     nor = temp.normalized()
>     area = 0.5*temp.dot(nor)
>     vol = area*nor.dot(v1)/3.0
>     centroid = (v1+v2+v3)/4.0
>
>     return (centroid, vol)
>
>
> for me in bpy.data.meshes:
>     me.update(calc_tessface=True)
>
>     sumc= Vector()
>     summ = 0
>
>
>     for f in me.tessfaces:
>         v1 = Vector(me.vertices[f.vertices[0]].co)
>         v2 = Vector(me.vertices[f.vertices[1]].co)
>         v3 = Vector(me.vertices[f.vertices[2]].co)
>
>         centroid, mass = handleTri(v1, v2, v3)
>         sumc += centroid * mass
>         summ += mass
>
>     print(tess_count)
>
>     print(sumc/summ)
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