Mesh deformation and VBOs

In my current project I render a series of basically cubic 3D models arranged in a grid. These 3D tiles form the walls of a dungeon level in a game, so they're not perfectly cubic, but I pay special attention to be certain all the edges line up and everything tiles correctly.

I'm interested in implementing a height-map deformation, which seems like it'd require me to manually deform the vertices of the 3D tiles, first by raising or lowering a corner, then by calculating a line between two corners and shifting all the vertices based on the height of that line. Seems pretty straightforward.

My current issue is this: I'm using OpenGL, which provides an optimization called VBOs, which basically are (to my understanding) static copies of the mesh kept in GPU memory for speed. I render using VBOs because I only use three basic models (L-corner, straight-wall, and a cap to join walls when they don't meet in an L). If I hav开发者_运维百科e to manually fiddle with the vertices of my models, it seems like I'd have to replace the content of the VBO every tile, which pretty much negates the point of using them.

It seems to me that I might be able to use simple rotation and translation transforms to achieve a similar effect, but I can't figure out how to do it without leaving gaps between the tiles. Any thoughts?

You may be able to use a vertex program on your GPU. The main difficulty (if I understand your problem correctly) is that vertex programs must rely on either global or per-vertex parameters, and there is a strictly limited amount of space available for each.

Without more details, I can only suggest being clever about how you set up the parameters...