Smooth groups for low poly building

Cody

Hey guys,
Trying to figure out the best way to set up the smooth groups on this rts model. I'm using max btw. Should each plane [top, side, other side] be a different smooth group? Is this right?

MoP

Yes, that looks right.

TSM

If you are going to normal map it, you could bevel your edges aswell. Performance would stay the same as using different "smoothing groups", since your breaking verts with the group splits, but your adding verts with the bevel (assuming your keeping them all on one group).

Although, only bevel if you normal map will give you that hard edge.

SouL

This might not be helpful to this thread at all... but just something that always confused me about smoothing groups.
Are you supposed to assign a NEW smoothing group to each section of geometry? What if for some insane reason you have 1000 different section. Do you create 1000 smoothing groups?

What about the edge shared between SG1 and SG2? What if you want that smooth? But still want a hard edge for the edges shared with SG3? How would you do that?

Just curious.

pior

Yo there (I guess I could walk down but I don't know where you sit haha)

On the example above you could very well have SG5 and SG1 being the same, for the exact same result.

also you can have a face be part of multiple smoothing groups, and obviously the reverse is true since a SG can pan on multiple faces. Basically you can have FaceA(SG1+SG2), FaceB(SG1+SG3). This can create interesting combinations like an edge going gradually from soft to hard, that kind of things.

I wish Max could give access to the 2 normals philosophies tho (either groups, or per-component hardness ala Maya). There is nothing that one can do that the other can't tho so that's all good!

(lunch break ends :P)

Cody

Thanks for the help guys. No, this actually wont be normal mapped, as our programmers can't get them to work with the crappy engine we are required to use. Also, due to the nature of this game, you wont really get close enough to this to require normal mapping. Might go back and do it later, but for the game itself, it's not necessary.

Eric Chadwick

If neighbor faces share the same SG then the edge between them is smooth. If neighbors don't share the same SG, the edge is hard. Easy.

But the cool trick in Max is that each face can be assigned to multiple SGs.

So for a super-low-poly face, like Ryno's here, you can make a hard edge between the lips, and still have smoothness at the corner. The faces at the corner have both 1 and 2, so they're smooth. But the lips are either 1 or 2. Dunno if that makes sense.

Never used Maya's setup, wonder if it allows this too?

Anyhow, smoothing groups suck. Bevels are so much better, same vert cost in-game, but you can control the amount of hardness simply by how close the two loops are. Better for normalmapping too, since the rays are cast more evenly, but you can still use bevels instead of SGs, doesn't require normalmapping.

DataCain

In Maya I think you select an edge and turn smoothing on/off for that edge?

I could be wrong, been a long time since I've seen Maya running - and I haven't used it myself.

Ghostscape

Eric, Maya lets you just click an edge and set it to hard or soft - honestly I think it's easier than smoothing groups 95% of the time - Smoothing groups took me a lot longer to work my head around than "hard edge/soft edge"

Bevels can be better but they're not always the best solution and they aren't going to provide the same level of hardness here with a single bevel and for an RTS I really can't see multiple bevels being necessary.

Eric Chadwick

Hard edges are horrible if you're baking a normalmap from one mesh (high-poly) to another (low-poly). If you're not baking, like you're just using Crazy Bump, or no bumps at all, then hard edges are better since it's faster. I try to avoid them though because they only make an infinitely-hard edge.