iOS Questions

paradise.engineering

Hello fine people of polycount, I'm here with some questions regarding iOS games in unity - specifications for us, 3d modelers.

1. Are there any specific texture formats, number of bits per pixel, number of colors or color palettes recommended for such projects?

2. Are the uv unwraps recommended to be non-overlapping?

3. Are there any types of polys recommended?

4. Any particular requirements/recommendations for the normals/bumps or specular maps?

I hope you will share your experience with us.

Thanks,
~p.e

Farfarer

1. No, Unity does the texture compression for you

2. Doesn't matter.

3. Doesn't matter, everything becomes triangles anyway, same with every game engine.

4. Can't use a lot of them on mobile, but it's no different to using them anywhere else. You'd be better of writing your own shader for normal/spec though.

paradise.engineering

Thank you very much Talon for this valuable information.

paradise.engineering

Bumping this with a new question:

5. Should we use Normals Maps since the games will run on iPhones or would that eat too many resources?

gsokol

You can use normal maps, but pixel shaders are a pretty big resource hog on mobile, so you would want to limit it to characters or small props most likely.

Elyaradine

Er... there are some other things you may want to think about too.

- The vast majority of your textures will likely use PVR compression, which results in a really small filesize.

- PVR requires that you use square, power-of-two textures. If you use non-square textures, there are some other file types (16-bit?), and they compress like crap. If you use RGBA, they generally compress like crap, or end up as massive files, so you've gotta pick a balance.

- There are some colour artifacts that happen when you use PVR compression. You should check your palettes after you compress on Mac to check. In particular, we've noticed greens being a little more prominent than the other colours, which becomes particularly noticeable in brown and grey colours.

- Remember that normal maps are useless on their own, because you need some kind of lighting for them to actually show (e.g. real-time diffuse or specular lighting). I guess it'd depend on the context, but you may be better off going with just map-based specular without much noticeable difference.

gsokol

Elyaradine wrote: »

Er... there are some other things you may want to think about too.

- The vast majority of your textures will likely use PVR compression, which results in a really small filesize.

Sorry to hijack the thread a little bit, but this is the first time I've seen anybody bring this up. Ive had terrible experience with compressed lightmaps...I get purples and greens all over the place...any advice on how to fix/limit that without using uncompressed textures?

Elyaradine

Unfortunately, not really.

The only "real" solution we found was to update Unity, as apparently later versions have a better PVR compression tool (same filesize, much better quality).

I tried a bunch of stuff with shifting hues and painting over, and had mixed success, but it was a mess and unreliable. Maybe there's some way to do the PVR compression outside of Unity, and have it not re-compress them...?

Lamont

Update Unity is the way, I used this app with a custom engine for iOS. It also has some neat-o tools too.

http://www.imgtec.com/powervr/insider/powervr-pvrtextool.asp