Long, thin triangles.

Rick Stirling

Avoid, or ignore?

In the old days we were always taught to avoid them, mainly because they were a bugger when it came to lighting (either real time or vertex baking).

These days, with per pixel lighting (or high end consoles and PCs), is it as important?

Thoughts?

Ryno

I get pretty bad shading problems with them. On cars with shiny surfaces, this is particularly noticeable. I'll usually try to make them long skinny quads if at all possible, as this terminates the smoothing more cleanly.

Joshua Stubbles

For the sake of keeping the mesh clean, I certainly try to avoid them. Though I'm not entirely sure it's as big a deal as it used to be. They're probably quite bad in some situations, such as having a reflection/environment map.

Same with tri-fans. They were a big no-no on PS2, with tristripping and all. But they're quite common today, it seems.

Squid

I would have thought this came under the heading of Optimisation.
any tri nearing a degenerative state is surely a waste of resources ?
The project i'm currently working on isn't games related, it does make usage of shaders (solid hulls for mri point clouds) and the biggest headache so far has been culling degenerate surfaces. If i had the option to manually trangulate an object then i wouldn't even think twice about it.
once you add any kind of deformation into the mix it just compounds the issues.

Jesse Moody

well i try to avoid them as much as possible but on my latest contract the client said not to worry about it. In max it was giving crazy lighting errors but once it was dropped into UE3, the diffuse was applied and spec you couldn't see it any more. But the surface isn't a completely shiny area too so having some dark colors is probably helping fix it.

But usually I try to avoid them long skinny tris...

Rob Galanakis

If it is any surface that deforms, I'd rather spend a couple extra triangles and fix it.

If it doesn't deform, it comes down to two things:
If this is a unique object with its own specific normal map, I would leave it, because the irregularities will be compensated for on the normal map.

If it is a non-unique object, for example, a rock or something that has a tileable rocky texture and normal map, get rid of them. In this case, the normal information from the long thin triangle will still show up with the lighting. It may not be so apparent (as the reason its really bad with vertex lighting is because it works via interpolation and it becomes really stretched out, as you know), but I don't "trust" those long thin triangles.

Tulkamir

Yea, on the game we're working on now I was told it doesn't really matter because the per pixel lighting will cover it up, and so far that seems to be the case. I still try to get rid of em all though, out of habbit if nothing else.

Rick Stirling

I always cull them myself - most of the time it's not an issue, I work mostly with characters and the never have them.

I take them out in environments because I always have done, so they offend me when present.

I ask now simply because when I give crits like "Avoid long, thin triangles because..", well I want to make sure it's sensible advice.

Or we could just be electric shock monkeys.

Sage

They seem to screw up lighting in Max. I thought they are bad to have because they cause smoothing problems when you bake normals from a higher res mesh as well if present. Is this true or I'm I just seeing things?

Alex