backface appears to not work

I am trying to use backface removal in 5.13.1. It appears to not work. Is this user error, or an issue?

  • Pre 6.0.0 master, builtin server, Linux
  • can.exo. Apply
  • Wireframe
  • Advanced. Backface - Cull backface
  • Advanced. Set Backface opacity to 0.01.
    Neither of these seem to work. Should I write this up?

In the Wireframe representation, you are showing line segments only - there isn’t a frontface or backface as in the Surface representation because the faces aren’t being shown.

However, there is an option Hidden Line Removal that you can enable to get the effect I think you are looking for. Here’s an example:

vs. Wireframe with Hidden Line Removal off:

Perfect explanation. Thanks. My tutorials were wrong, I will update them when I am working in a few weeks.

I thought the backface with wireframe used to work. I thought the wireframe was draw by drawing the polygons with an edge-based rasterizer so front/back was still known.

Maybe the way we do wireframe is different. Maybe the support for this in OpenGL is gone. If this does not work, we should probably at least remove wireframe as an option for the backface representation.

What I remember is what you state. However, really what I am looking for was Hidden Line Removal.

I agree with Ken that if wireframe won’t work with backface, we should remove the option.

I’m a bit confused now. With Wireframe the primary representation and the Backface Representation set to Surface or Surface With Edges, we get what we expect. Backface Representation set to Points or Wireframe might be working, but it is impossible to tell. Cull Backface is the only one that clearly doesn’t work. So there might just be a bug here.

Um … no. This is 6.0.0-RC1, Linux, builtin server.

Here is front face wireframe, back face surface.

Here is front face wireframe, back face Surface with edges:

Cull backface: (Note this looks exactly the same as backface wireframe) (Basically, I think front face is drawing both faces…)

I reproduce what you see with can.ex2. I was looking at a wavelet source with backface set to surface:

and surface with edges: