Have you taken a look at the command patch ? For example
patch('Vertices',V,'Faces',F,'FaceVertexCData',D,'FaceColor','interp','EdgeColor',somecolour,'FaceLighting','phong');
Suppose that you have N points
V are the spatial positions of the points: What you call coordinates.
F is a matrix of M rows and 3 columns. Each element in each row is a point (row in V). The three points define a triangle like the one in your figure example.
D is the stress value at each point.
The other options only change the colour presentation. "somecolour" should be replaced by a colour.
You can use in addition
colormap somecolormap;
colorbar
for changing the colormap (between hot, gray, or your own definition) and to add the colorbar.
Hope this helps. Best regards
