Contour of a 2d projection from 3d data

Hi I am given many vertices and faces for a tree with 4 branches (2 on the side and 2 at the top). I need to look at X-Y and Y-Z projections with only the outlines displayed. If I simply plot (x,y) and (y,z) then all internal points fill the projection and I can't figure out how to get rid of them. I cannot simply use xmin and xmax, because that gets rid of parts of the branches Thanks for your help

Answer 1

[Mike Garrity]

Look at the approach I used in my answer to this question .

The basic idea is that you use surf or patch or whatever you're using to draw the 3D object, but replace either the X,Y, or Z data with a constant array of the same size (the zeros(size(xs))+1.5 parts of the first 3 calls to surface in that answer).

Does that make sense? If you need more details, I'd probably need more details of how your 3D object is represented.

[Timur Navruzov]

Yes it does make sense. I used your analogy and took a cross section through z=0 as the object is symmetrical around the axis. If I equated all z=0, it still draws all the points and fills the picture with colour. Thank you for the idea though