> Thanks for working on this.  The results in p.b-t.b look great!  Your
> contribution is appreciated and I will work to incorporate this fix into
POV
> 3.5.

Glad to have done it.  Just wanted to get it right.

> You completely rewrote MTransUVPoint.  Really, what you've created is a
new
> function, not a new version of MTransUVPoint.  Your function takes
> completely different inputs and yeilds a different output.  This new
> function deserves a new name.  Do you have a suggestion?

I thought about this.  The 'M' in the name stands for matrix so that can go.
It is still a transform of the uv point into the parametric space of the
texture quadrilateral as it exists in 2d texture space.  To avoid confusion,
it might be a good idea to keep the name TransUVPoint or at least keep some
indication that it is a 2D tranformation of a point.  I'm not really sure
what the appropriate name for the mapping would be but it seems to be a
bilinear mapping.  The function uses the parametric form of the edges of the
quadrilateral and inserts the u and v parameters into the equation.  It
first finds the two U intersections along sides and then uses the line
defined by those two point to find the V intersection.  The parametric
representation of a line is:

x = x1 + t(x2-x1)
	y = y1 + t(y2-y1)

where t is the parameter.

the input is
p - uv parameters
st - four corners of quadrilateral (texture coords)
output
t - intersection

> Also, since MSquareQuad does not need to be called, we'll probably remove
> the call, but leave the function.  It is part of the general collection of
> matrix functions, so it will probably stay in case sombody needs to use it
> in the future.  Also, if Shape->Mapping is no longer used, we should
remove
> it completely.  I'm not sure if it is used anywhere else - do you know?

If you keep MSquareQuad, it might be a good idea to add a note to the effect
that it finds the projective mapping matrix and infers a perspective
mapping.  The Shape->Mapping isn't used anywhere else so yes it can be
removed completely.

> One more question:  Do you have a simple test scene that I could use for
> testing?  (Maybe with two patches with a pattern-based texture.)
Thanks!!!

Scroll to the bottom of my original post.  I included a small test scene
there with two patches and a pattern for the texture.

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