"Bald Eagle" <cre### [at] netscapenet> wrote:

> I spent some time pondering the boundary conditions, and how to process 16
> patches like the stitched renders.
> What I've come up with is to
> create an array of 25 corner points
> create an array of 16 points, and "copy" the relevant corner points into the
> appropriate places
> calculate the linear vectors between the corners of each side
> set the control points on those sides to 1/3 and 2/3 of the vector
> Use those control points to interpolate the 4 inner control points in an
> analogous manner

So, I tried a slight modification of the above, following your suggestion, and
what your diagrams/renders imply, and I got 16 connecting patches - but with
sharp seams.

I used 4 vectors describing the edges between the 4 corners, and divided them by
3.   I then used those vectors to describe the control points by adding them to
the corners, and adding 2 vectors to a corner to get the 4 inner control points.

It makes sense that it's not smooth, or curved, because everything is just on a
line, and the non-corner control points aren't really control points by this
method - they're just passively following along with the corners.

So I ignored the y part of the vectors and just made "level" sub-patches, and
that seemed to give me something resembling your stitched patch render.


I know I'm still probably a ways off from what you've got - and pretty far off
from what I originally envisioned, but that might possibly be overkill.

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