[cairo] Mesh Control Points

[Lawrence D'Oliveiro]

On Sun, 16 Apr 2017 17:24:49 -0400, cecashon at aol.com wrote:

> I put together a little program that can dynamically draw a "tiled"
> mesh. It is working but I am having trouble understanding how P0, P1,
> P2, and P3 change the drawing. Looking at the documentation for
> cairo_pattern_create_mesh() it shows these control points inside the
> mesh. Where should all four control points be so the mesh would be
> the same as if it had no P control points?

This is “Coons patch” (PostScript type 6) versus “tensor-product
patch” (PostScript type 7) patterns. See around page 286 of the
PostScript Language Reference Manual, Third Edition
<https://www.adobe.com/products/postscript/pdfs/PLRM.pdf> for a
detailed description of how the former is a special case of the latter.

The control points can be anywhere in relation to the mesh, even
outside <http://default-cube.deviantart.com/art/Tensor-Patch-522195315>.