Hi!
A couple of days the project for new bump map system was added in Trunk. And for my surprise it´s work too in BGE!
So now we can make some good things like paint bump maps instead of sculpt to add model details or use the same texture to difuse and normal channel!
It´s really great ^^
I don´t know exactly how much it´s faster ( or not ) than the normal map shader but it´s really cool xD
Some Tests:
Bump map painted in view3D - used procedural cloud map as brush
I can’t be absolutely certain without trying some benchmarks first, but there’s good odds that this will be noticeably slower- since the bump map has to be converted into normals before it’s useful, whereas a normal map has that step done beforehand. What you could do though, is use the bump map while developing, and then just bake all your bumps into normals (or use an outside program or GIMP or Photoshop plugin to do it) before releasing the game. That way you get the ease of working with bump maps during development, but the speed increase of normal maps in the final release.
Of course, I could be wrong, maybe normal maps aren’t any faster, but I doubt it.