Dancing Phantoms

Spent most of the day trying to figure out how to deal with geometry that has to be available to both the haptic and graphics subsystems. The haptics subsystem has to run fast – about 1000hz and gets its own callback-based loop from the HD haptic libraries. The graphics run as fast as they can, but they get bogged down.

So the idea for the day was to structure the code so that a stable geometry patch can be downloaded from the main system to the haptics subsystem. I’m thinking that they could be really simple, maybe just a plane and a concave/convex surface. I started by creating a BaseGeometryPatch class that takes care of all the basic setup and implements a sphere patch model. Other inheriting classes simple override the patchCalc() method and everything should work just fine.

I also built a really simple test main loop that runs at various rates using Sleep(). The sphere is nice and stable regardless of the main loop update rate, though the transitions as the position is updated can be a little sudden. It may make sense to add some interpolation rather than just jumping to the next position. But it works. The next thing will be to make the sphere work as a convex shape by providing either a flag or using a negative length. Once that’s done (with a possible detour into interpolation), I’ll try adding it to the graphics code. In the meanwhile, here’s a video of a dancing Phantom for your viewing pleasure:


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