Hi Radiance,
quote:
look at the cone in the first image. the vertex normals are shown as the lightblue lines.
Yeah, those are problem vertex normals, since they were created without regard to the desired surface breaking.
MoI and other CAD programs will never create improper vertex normals like you are showing there, in a CAD program the upper cone surface is a separate logical piece from the bottom cap surface.
When MoI exports to OBJ, it writes all exactly proper vertex normals into the file, it will never make ones like you show in that first image. Every single normal is already set up to point in its proper direction to make the right appearance.
So it is important when reading in stuff from a CAD program, to not try and do any manipulation or "fixing" of the problem you show because instead of fixing things you are actually going to be disturbing the vertex normals which are coming from the NURBS surfaces.
quote:
1. split the cone triangles and the base triangles into 2 groups, eg smooth groups. the renderer still uses the supplied vertex normals, but it does'nt interpolate vertex normals shared between 2 groups during rendering (i'm not talking about remaking / averaging new normals, i'm talking about computing the shading tangent from the vertex normals during raytracing)
Still what you are writing does not really make sense - when using the vertex normals you should not be interpolating anything between faces at all, you already have the vertex normals for each vertex of a face, you should only be interpolating within a single face and not between faces.
If you are trying to interpolate between faces, it means you are messing around with making vertex normals instead of using the supplied ones which already are set up at every face.
Anyway, the simple case is to look at the cylinder example I posted above, if that does not render as a smooth looking cylinder then it means you have vertex normal handling problems. That's about as simple as I can make it.
Every other rendering program that utilizes the vertex normals from the file will make that cylinder look like a completely smooth cylinder, but it does not look that way in Octane.
- Michael
