Vertex Optimization techniques

MikeF

with my current project i'm limited to 256 tri/vert/texture size and while the tri count isnt too difficult, keeping the verts low is throwing me off.

i've been reading through the wiki about keeping UV islands to a minimum and reducing the ammount of smoothing groups, but that doesnt seem to be shaving much off......

The biggest thing that is preventing me from using fewer smoothing groups and islands is having to have all the assets normal mapped, so if there's any other tips or tricks out there i'd really apreciate it.

Ben Apuna

Why so much emphasis on optimization?

It seems to be a pretty common sentiment around here that you shouldn't optimize to the point that your assets don't look good especially when normal maps are part of the equation since that would imply that you are running on at least semi-modern hardware.

Are you developing for mobile devices that require such heavy optimization? If so it seems like normal maps would be sort of out of place.

Aside from that, you could try intersecting geometry to save on verts, though that generally leads to unoptimized UV layouts...

A look through the low poly thread might yield some good ideas and techniques.

But you probably know all of that anyway...

Pics of what you are trying to optimize would probably help get you better suggestions and feedback.

MikeF

the assets in question are actually being used for a custom engine built for the ipad that supports normal mapping, so in this case vert counts are very crucial... I'l have another look through the low poly thread in the morning, thanks Ben

Numerator

Here is some more info:
http://home.comcast.net/~tom_forsyth/papers/fast_vert_cache_opt.html

Snader

Even if you were to make 1 long triangle strip, you'd still only have 254 triangles. Doesn't sound like a feasible amount of polygons for a game. (except maybe Battlezone but that doesn't need normalmaps)

Ben Apuna

@MikeF:

Custom iPad engine, that's cool.

I didn't mean to imply that you weren't going about this the right way. It's just that sometimes people get funny ideas about optimization and take it too far.

I wish I had more info to offer, I haven't done any "low poly" stuff in a long time.

I think you'll end up having to experiment with what you can get away with when combining normal maps with completely smoothed (1 smoothing group) objects. Maybe you can get your engine programmer to implement something like 3point's Max shader in your engine. A properly synced shader like that would probably allow you to drastically reduce the number of smoothing groups needed for a clean normal map bake.

Eric Chadwick

If you can use object-space maps instead of tangent-space, that would really help reduce the vertex count, since you don't have to worry about extreme-angled vertex normals skewing the map.

But... object-space maps usually compress like crap. Some ideas here...
http://developer.nvidia.com/object/real-time-normal-map-dxt-compression.html

At that low of a model resolution though, the best bet would be to ignore lighting altogether, make everything fullbright and paint the lighting into the textures. At least for "rounded" models. Height-mapped terrain might still look great with tiled normal mapping, since the vertex normals are usually pretty smooth (don't have to curve around sharp edges).

MikeF

@Ben
not at all man, i appreciate any input here.
unfortunately this is for a contract so i have very little input of the technology being used, especially at this point in development. It never even crossed my mind to use object space maps, that would solve tons of headaches, unfortunately its just not possible.

Thanks for the input everyone, i'l see what i can do. I might be able to bend my NDA if i only show specific parts of the models, i'll contact my client later today