textures in Unity on IOS

GoK

Ok hope someone can give me a little heads up here. I want to use multiple materials for an environment running in Unity on IOS prob, everything above 3GS, now here is the issue... I want to bake the shadows/ambient occlusion to a separate UV channel, I have been told this will give me a drastically large hit to the frame rate.. is this true and if so does any one have any suggestions or alternatives?

Thanks guys!

Jody

poopipe

It's probably true - it'll require another pass on the shader which is hard work for an iphone.

You're probably better off using unique textures in a lot of cases as the phones have a lot of graphics memory and not a lot in the way of cunning GPU features.

This is based on the renderer I work with - I don't know enough abut the underside of Unity to say for certain

GoK

Ah right cheers. Using unique textures would be fine if I can use enough. Do you have any ideas, even a rough estimate, of how many textures I can use per scene? Assuming a worst case scenario I have 4 characters rigged on screen, I'm just using diffuse textures and all textures are 512*512...

Thanks again!

poopipe

you've got 60 odd mb to play with if memory serves - thats for everything though, not just textures

Farfarer

Unity does have all this built in.

Check the Beast lightmapping stuff, ensure your models to be lightmapped have generate lightmap UVs ticked (or your model has a lightmap UV channel) and are set as Lightmap Static. Ensure the materials have a lightmapped shader.

The hit isn't that significant (other than another texture call). Only way to tell for sure is to give it a go.

Lightmaps're fine on Android for me (not got any iOS stuff to test on).

poopipe

it'll depend a lot on the phone I'd have thought - an s2 is not the same as a desire

It's probably safe to assume that unity will take care of the oily bits and youll get decent performance out of what you want to do though - my comments are based on the understanding that fill rate is usually the sticking point on iphone so you want to minimise the number of times a pixel gets touched

Brice Vandemoortele

There is no 'second pass' (a 'pass' draws the whole geometry a 2nd time) for lightmaps on iOS.
3GS can access up to 8 textures in a single pass if I recall correctly.
You'll get the best performance by using vertex colors for lighting, but performances are ok with lightmaps even on the oldest devices.

Avoid transparent/additive/"blended in any way" materials, they're killing the fillrate: iOS use tile rendering - a sort of defered rendering - which is very efficient with opaque meshes.

Have a look at this for iOS optim in Unity:
http://blogs.unity3d.com/2011/08/18/fast-mobile-shaders-talk-at-siggraph/

poopipe

I stand corrected

thats interesting, not the way ours works at all..

easterislandnick

If you are using static lighting on your background (no realtime light effects) then write a shader that only calculates the diffuse combined with the lightmap and does not calculate lighting on the geometry at run time, it will speed things up immensely.