These are 3D art asset modeling, rigging, uv-mapping and texturing tips. And not only for low-poly though it is where they are needed the most. See also other tip collections, the first and second set.
Minimize number of Draw Calls the Asset generates
- Have each character as one single mesh. Characters that are made from pieces in-game cost in draw calls.
- Combine separate static meshes to one. If you can have a collection of objects as one object, one file(the meshes can be unconnected), it is better than as several files. But don’t combine a whole village to one object as the whole thing would get loaded to memory even though you may not need it. This trick is best for moderate collection of objects, say all items inside a shop interior.
- Use only one material and texture per object. Or even..
- Have several objects all use same texture and material. This means each has the same uv-map but uses only a portion of the whole – uv-map collects all textures together. See picture. Even though not shown in picture(for clarity) the sections different objects use can well overlap.
Optimize character rig, use 2 rigs – one for animation and one for export
The less bones your character has the lighter it is to run. And less resources used for one character means more to use elsewhere – maybe even allowing more characters.
But very few bones makes animating difficult and prevents many motions. Of course we rather animate with the optimum amount – and with control objects as well to make work easier. Sure you can have control object in your game rig and just make sure not to export them to game, but having bones in a rig that you don’t export, like between one bone and another? That is asking for trouble.
Solution is two rigs, one for animation and one for exporting to game. Game-rig is linked to follow animation rig – you animate only with animation-rig and export only with the game-rig.
[one_half]Animation Rig is the rig you build first. It has the bones and control objects you want to animate with. The rig can even have details, like fingers, which you can animate and later decide to use or not(via the game rig). Build your animation rig and then consider what parts of it are essential for moving the character. Every bone in a character only supporting other bones and not really affecting the mesh itself is a bone the game character does not need. So, do you really need the neck-bone if head and chest bone playing together can offer the same result or close enough?
[one_half_last]Game Rig is collection of helper objects(any type, also called nulls), one per every important part of character. The reason to use nulls instead of bones is that creating bones is intended to build hierarcies you don’t need and should not have, here. Create these objects, then align and parent them to follow the relevant bones of Animation Rig. They should relocate to pivot-points of the animation-rig-bones. Then skin your character mesh to these helper objects(nulls). In the end you animate with Animation Rig and the Game Rig follows and deforms the mesh.[/one_half_last]
That was the 3rd set of little tips for improving 3D (game) art assets. Cheers!