"clamp" to mesh

[NINE78]

Dear all,

I'm trying to find the best way to "clamp" a mesh to another. Let's say I have some sort of "terrain" mesh in the X/Y plane (Z is up/down) and a "road" mesh across that terrain. Both come from different databases and the Z coordinates do not necessarily line up. So I'd like to clamp (project) the road to the terrain to avoid any inconsistencies.

We're talking potentially very large meshes here, so I'd like to avoid doing this all in javascript (doing bilinear interpolation for the 4 terrain vertices around each road vertex or so). Is there any way this can be done in the road's vertex shader or so? This might be wishful thinking, but any pointers would be greatly appreciated.

thanks!!

[mrdoob]

I can't really think of a fast way for doing this. Did you come up with something in the end?

[NINE78]

Not really anything earth-shattering. I'm basically colliding every vertex of the "decal" mesh to the "terrain" surface. I was able to use certain properties of the terrain mesh to speed up the search for the face I'm looking for the decal vertex will collide with...

I was just reading up on perhaps pushing out this work to a Web Worker... Do you have any experience with this? I have read that pushing the meshes in JSON between the main thread and the web worker might kill things as well...