Can TPolyLine3D be hidden by 3D content?

Hi there,

I have a 2D histogram being drawn as “surf2”. I would like to overlay lines hugging the
surface, going covering all y at intervals of constant x to give context to the features of the plot.
Essentially, this is somewhat like “surf1” but with lines going only in 1 direction and not every bin.
(I find “surf1” to be too busy for a plot with many bins).

I am able to draw the lines with TPolyLine3D just fine but it looks awful because these
lines are not hidden by the hills and valleys where they should be (like the overlaying grid
behaves for “surf1”). Another way of saying it is that the lines do not “obey” the rules
of 3D viewing.

Perhaps this is the wrong approach, or there is an option I haven’t yet discovered?



Yes, this cannot work the way you expect. The 3D polylines do not know a filled surface was drawn before.

OK – but it does make me wonder how general the usefulness of TPolyLine3D could be if it doesn’t behave or have the option to behave this way.

Is there some other solution to the problem of getting such lines drawn on the surface in a viewable way?

Using SURF2 as you do would require some developments. I am not even sure that something achievable. TPolyLine3D and SURF2 are drawn is a completely different way. They ignore each other. May be going to OpenGL would help.