[Bf-funboard] Differencing Cubes

[Ken Hughes]

Roger wrote:
> For some reason verts  have been added  to edges around the removed space 
> creating unnecessary edges added to the object connecting these extraneous verts 
> to corner verts of the first cube.
> It seems that blender has to make it into triangles when quads are required.
> Why ??
> There is no need to add verts along an edge, cut edges or make triangles.
>
> Is this a bug or am I doing something wrong.
>   
It's a bug.  The current boolean algorithm works on tris; it 
preprocesses all quads into tris, does the  operation, then merges faces 
back together.  The current merge algorithm suffers from a general issue 
of numerical precision.  I committed a new merge algorithm to svn about 
two weeks ago that fixes this problem in most, but not all cases.

Ken