Add support for position quantized [PNTS]

[pizza3]

Fix #280

[gkjohnson]

Thanks! Have you been able to test this in a dataset? Are you able to provide a PNTS model to test this functionality with?

[pizza3]

Hey @gkjohnson, so I tested it using this pnts file first on the cesium ion just to get the general idea of the result, then used it for the testing over here with the PNTSLoader, I was able to get the features following the spec document mentioned on the issue and produced the result.

[gkjohnson]

Hey @gkjohnson, so I tested it using this pnts file first on the cesium ion just to get the general idea of the result, then used it for the testing over here with the PNTSLoader, I was able to get the features following the spec document mentioned on the issue and produced the result.

Thanks! I'll give that a test when I get a chance once the above question is answered.

[gkjohnson]

Just gave it a test - the test model you provided above as some very large offset values ([ 1215007.8828876738, - 4736318.051199594, 4081600.22126042 ]) which is causing the points to jitter when the camera is looking at them. This is handled in the I3DMLoader by applying the offset as a transform rather than to the float 32 buffer values themselves. So I think we should instead apply this scale and position offset to the mesh transform rather than the points themselves since they'll be multiplied with the camera transform on the CPU which will alleviate floating point issues on the gpu.