Fix coplanar check

[andrewheumann]

BACKGROUND:

• Our Vector3 coplanarity check failed for certain input that it should have accepted, which was causing immediate failures on deserialization, breaking several functions.

DESCRIPTION:

• Rewrites the coplanarity check to use a dot product method instead of a triple-product method. The triple-product computes a volume, which means there's no sensible way to think about it in terms of Vector3.EPSILON — the dot product lends itself nicely to the interpretation of "check that the points are within EPSILON distance of a plane passing through the first three non-coplanar points"

TESTING:

• I added some tests, including one that would definitely have failed with the old method.

REQUIRED:

• All changes are up to date in CHANGELOG.md.

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This change is 

[wynged]

one refactor suggestion

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @andrewheumann)

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Elements/src/Geometry/Vector3Extensions.cs line 24 at r1 (raw file):

            int p1Index = -1;
            int p2Index = -1;
            for (int i = 1; i < points.Count; i++)

might be nice to pull this first step out into it's own method. FirstThreeNonCollinearIndices
Maybe even TryGetThreeNonCollinearIndices which would let you retrun true below without additional checks, but that might be messy with out variables etc...

[andrewheumann]

Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @wynged)

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Elements/src/Geometry/Vector3Extensions.cs line 24 at r1 (raw file):

Previously, wynged (Eric Wassail) wrote…

might be nice to pull this first step out into it's own method. FirstThreeNonCollinearIndices
Maybe even TryGetThreeNonCollinearIndices which would let you retrun true below without additional checks, but that might be messy with out variables etc...

OK, did my best... I think it's still a little ugly, but it works.

[wynged]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained

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Elements/src/Geometry/Vector3Extensions.cs line 24 at r1 (raw file):

Previously, andrewheumann (Andrew Heumann) wrote…

OK, did my best... I think it's still a little ugly, but it works.

wfm!