Alain <aze### [at] qwertyorg> wrote:
> In most cases, it's the average of the normals at the center of the 
> triangles touching the point. If not the actual average, then reasonably 
> close to that.

  Calculating vertex normal vectors by averaging the normals of the
triangles sharing that vertex (possibly weighted by the area of the
triangle) is a common way of smoothing a mesh when the only available
information is the raw triangle set.

  In theory if the mesh has been created from a mathematical surface
(eg. an isosurface, a NURBS or some other algorithmically created surface)
the optimal vertex normal would be the true normal of that mathematical
surface at that point. Of course this requires that you can figure out
the math to calculate the normal at any point on the surface (often this
requires derivatives, although sometimes it can be deduced by the way
the mesh is generated).

-- 
                                                          - Warp

Post a reply to this message