r - Plotting surfaces with contour map in 3D over triangles - Stack Overflow

The example code here for rgl does almost what I want. However my (x,y) are not in a rectangle but in a triangle that is half of the rectangle (x=0..1, y=0..1 and z is missing if x+y>1). My input

Contour plot in R [contour and filled.contour functions]

r - Adding Contour Lines to 3D Plots - Stack Overflow

Reduced basis stabilization and post-processing for the virtual element method

python - Problem with 3D contour plots in matplotlib - Stack Overflow

plotting - How to Create a Contour Plot on a Surface of a Unit Sphere from a Table of Values? [SOLVED] - Mathematica Stack Exchange

ggplot2 - how to plot three dimension data or four dimension data to filled contour plot or surface plot in R - Stack Overflow

r - Adding Contour Lines to 3D Plots - Stack Overflow

Performance evaluation of resin wafer electrodeionization for cooling tower blowdown water reclamation, Sustainable Environment Research

Field-dependent deep learning enables high-throughput whole-cell 3D super-resolution imaging