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

r : 3D surface plot - Stack Overflow

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Calculating the solvent density around a protein — MDAnalysis User Guide documentation

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

Clamping force model application on the aircraft structural assembly

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Plotting a 3D surface plot with contour map overlay, using R - Stack Overflow

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

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