Tips for developing 3D games on newer engines targeting old hardware

Question

I see a lot of examples and tutorials for 3D engines like Unity3D, UDK, Source etc. They all seem to be under the assumption that you are making a game for current(ish) hardware.

I would like some tips or tutorials on how to develop a game using UDK, Unity3D or any other modern game engine while targeting what might be considered ancient hardware.

Hardware specs might be as low as

• 1GHz-1.8GHz single core CPU
• 8MB-64MB Video chip
• 512MB-1GB RAM

Thinking along the lines of older laptops or old business class machines that might have, at most, an Intel GMA900 chip or a ATI Radeon 9000 chip onboard.

Answer 1

1. Test, test, test! Find someone with or buy an old laptop, if you're looking to sell your creation, the expense is worth it.

2. Keep polygon counts low! Many older Intel devices run vertex shaders on the CPU, which can very quickly become the bottleneck.

3. Use appropriately sized textures! Texture bandwidth on older hardware isn't great, so avoid using more pixels than will be displayed on screen.

4. Avoid complex pixel shaders/materials! Stick to simple blending operations, and reuse them as much as possible.

5. Profile! If possible, provide special development modes to help find bottlenecks like:

   • Replacing all textures with a single 1x1 texture
   • Swaping all models with a simple cube
   • Replace all shaders/materials with minimal versions

Answer 2

Well given that unity targets iPhone then iPhone 3G (not S) has pretty ancient fixed function style hardware. You should have no trouble getting software written for an iPhone 3G to run on older hardware.

Beware the driver bugs though!!