The question is how. 1) Each footstep is a decal, which is unusable, or very hard to implement on rough terrain 2) All the footsteps are rendered to a texture and then multitextured on the terrain? I'm sure this problem is solved already, but I can't find any info about it. Thanks.

Quote: Original post by szecs
The question is how.
1) Each footstep is a decal, which is unusable, or very hard to implement on rough terrain
2) All the footsteps are rendered to a texture and then multitextured on the terrain?

I'm sure this problem is solved already, but I can't find any info about it.
Thanks.

Either way will work. For footprints I would prefer the first, since the terrain usually isn't rough at that level of detail, and a few thousand decals shouldn't slow anything down (that is the cost of one particle system, and static to boot).

That strongly depends on how you do unique texturing of your terrain at all. Nowadays you would go for an approach such as mega texturing. That means you have a very big texture (or rather a bitmap) with a unique area for each part of your terrain. You then extract smaller textures from this mega texture for those parts of the terrain you actually render.

That means in turn you can update parts of the mega texture if your terrain changes for whatever reasons. So you can blend the footsteps directly into the mega texture or a unique dirt texture. Try googling for "megatexture terrain rendering".

Granted, the decals approach would also work but comes at cost of terrain roughness inconsistencies. While this might not be an issue for comparably small footsteps measured against the terrain roughness this limits your approach to small decals.

Thanks for the quick replies.

The truth is that I'm working on a tank simulator, so the trace of the tank is relatively big to the tank and the terrain roughness, so the decals are problematic to use. (I don't speak English so well, that's why I used "footsteps").

So rendering to texture is a good approach. It means an extra rendering pass, but since rendering the "footsteps" without any testing is very fast, I think it is not slower than the decal technique. But it's quite tricky to determine the size and the place of the texture relative to the terrain.
Or I should learn the megatexture terrain rendering.

Or any other ideas?

Thanks.

I think you should look into using megatexturing for the tracks.
If you do you could even use that data to deform the ground, like they do in the game motorstorm.