All of my models have a colour, specular and normal map (tangent space) for them. I’ve recently heard about light mapping. Can someone quickly explain what that does and if it is necessary when I already have colour specular and normal.
Lightmapping is simply lighting that’s been turned into a texture to avoid having to use real time lighting and to provide better lighting.
There’s more info in the manual and on google, but basically, you have your object using UV1 and then take it into something like 3DS MAX, or if using Unity 3, use Beast lightmapping. To bake all the lighting information in a scene, into a texture which is then applied to your objects using UV2 (which you can share across a bunch of objects). Which lets you have fancy lighting, global illumination etc. which to do in realtime would even today be pretty taxing for a computer to manage.
Naturally lightmaps aren’t much use when objects are moving, or for dynamic lighting in general (Doom 3), in which case you’d use your real time lighting too. Both work well together.
Most games use lightmapping in some way because it provides far better quality than realtime lighting alone, and has practically no negative effects on frame rate.
Do you NEED to use lightmaps? No, there’s no laws saying it’s required, and you may find it doesn’t help at all. It’s all dependent on the project.
Yup, spot on answer there. Here’s the Beast schwag demo’d on the blog:
http://blogs.unity3d.com/2010/07/15/unity-3-feature-preview-beast-lightmapping/