scott <sco### [at] scottcom> wrote:
> >  That's not always possible. Simple example: A torus composed of quads,
> > and a rectangular texture image wrapped onto its surface. The texture will
> > be distorted at the places where the quads are non-rectangular.

> True, but if you use enough quads that your torus looks like a torus and not 
> like a jaggedy square wheel the distortion is going to be minimal.

  May be feasible for non-realtime rendering, but not real-time games
where you need such shapes.

>  And 
> anyway, won't you have exactly the same problem using triangles instead of 
> quads - the renderer can only interpolate linearly and a rectangular texture 
> on a torus needs a non-linear interpolation to be correct.

  At least with triangles you can lessen the problem by making the
triangles as equilateral as possible (iow. each "row" (in torus
coordinates) of vertices is at the middle of the previous "row" of
vertices). Sure, the texturing will still not be technically perfect,
but at least the error is much less glaring, at least on a torus shape.
With quads the error becomes very visible, especially if the quads are
large.

-- 
                                                          - Warp

Post a reply to this message