TRICONT and TRICONTF have functionality equivalent to that of CONTOUR and CONTOURF, but the surface is defined over a 2D mesh of triangular elements (which may have a non-convex hull and/or may contain interior holes).
Works wonderfully, better than previous submissions (tricontour). The contours of my mesh were being split with tricontour (produced two contours, even though same level and connected), but tricont produces the correct contours. Saved me a lot of debug time.
I've been waiting for someone out there to do triangular mesh filled contours for ages now (I did have a go a trying to code myself but found it very tricky to make it generic). Hats off to you Rich. I haven't tested thoroughly but tidiness of code and what it promises to do means I'll give it 5 anyway!