Change index buffer to a straight color buffer instead of display list

[ctralie]

I noticed looking at one of my students running the code yesterday that there's a potential bug with the way the background is rendered, and I think it would be a lot cleaner if I just used a different color buffer when rendering indices instead of doing a full fledged display list

[anny0316]

Hello ctralie:
I have some questions:

1. In Utilities2D.py, an error occured: unresolved reference 'Point3D'.
2. In meshView.py, this function makeLaplacianMatrixSolverIGL cound't find ,in line 108, and 'anchorsIdx, anchorWeights' cound't find in this function.
3. In RealSenseVideo.py, 'from VideoTools import *', but how to find VideoTools?

thanks a lot!