Add a guard to faceNormalPointingOutward to detect degeneracy

[SeanCurtis-TRI]

This adds the triangle_area_is_zero test to faceNormalPointingOutward (with assert effect).
This is a prerequisite to the isOutsidePolytopeFace test. The test is
rendered meaningless if the reported normal is defined by numerical noise.
If a scenario is failing due to the isOutsidePolytopFace assertion
failing, this will detect if it's due to face degeneracies.

relates to #322

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This change is 

[Levi-Armstrong]

@SeanCurtis-TRI I have several test in my new environment library and when I check a box to cylinder I receive the following error. My plan is to push the test back to FCL which are checking each shape to another with different conditions.

The box is 1m x 1m x 1m at <0,0,0>.
The cylinder is <0.25,0.25> at <0.2,0,0>

tesseract_collision_box_cylinder_unit: /home/larmstrong/catkin_ws/trajopt_public_ws/src/tesseract-1/tesseract_ext/fcl_ros/fcl/include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h:848: ccd_vec3_t fcl::detail::libccd_extension::faceNormalPointingOutward(const ccd_pt_t*, const ccd_pt_face_t*): Assertion `!triangle_area_is_zero(a, b, c)' failed.

[SeanCurtis-TRI]

That's good to hear. And thanks, @Levi-Armstrong for the very specific example. Nice to know we can recreate this problem without having to create a Convex. So, the problem (or at least one problem) is that we are generating degenerate faces.

@hongkai-dai this doesn't seem overly surprising. Something to look into.

[hongkai-dai]

Let's discuss this f2f tomorrow.

When we rewrote the EPA implementation, we know that it didn't handle the degenerate cases, and decided to handle degeneracy in future PRs. Now it seems like a good time to work on the future PRs.

Reviewable status: 0 of 2 files reviewed, all discussions resolved

[SeanCurtis-TRI]

+@hongkai-dai for review please

Reviewable status: 0 of 2 files reviewed, all discussions resolved

[hongkai-dai]

+@sherm1 for platform review please.

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved

[sherm1]

Nice! with a few nits.

Reviewed 2 of 2 files at r1.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @SeanCurtis-TRI)

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 776 at r1 (raw file):

  //
  // For dimension i, two values are considered the same if:
  //   |pᵢ - qᵢ| <= ε·max(1, |pᵢ|, |pᵢ|)

Minor: second pᵢ -> qᵢ

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 777 at r1 (raw file):

  // For dimension i, two values are considered the same if:
  //   |pᵢ - qᵢ| <= ε·max(1, |pᵢ|, |pᵢ|)
  // And the points are coincident if the previous condition for all

Minor: condition for -> condition holds for

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 789 at r1 (raw file):

        max({ccd_real_t{1}, abs(p.v[i]), abs(q.v[i])}) * eps;
    const ccd_real_t delta = abs(p.v[i] - q.v[i]);
    if (delta > scale) return false;

Nit: the "scale" here is scale=max(|pi|,|vi|). Then the tolerance is
tol=max(1,scale)*eps and the final condition is delta > tol. Consider writing it like that to be more precise.

[SeanCurtis-TRI]

Done

Reviewable status: 1 of 2 files reviewed, all discussions resolved (waiting on @hongkai-dai and @sherm1)

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 776 at r1 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

Minor: second pᵢ -> qᵢ

Done

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 777 at r1 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

Minor: condition for -> condition holds for

Done

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 789 at r1 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

Nit: the "scale" here is scale=max(|pi|,|vi|). Then the tolerance is
tol=max(1,scale)*eps and the final condition is delta > tol. Consider writing it like that to be more precise.

Done

[sherm1]

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 789 at r1 (raw file):

Previously, SeanCurtis-TRI (Sean Curtis) wrote…

Done

No change?

[SeanCurtis-TRI]

Reviewable status: 1 of 2 files reviewed, all discussions resolved (waiting on @hongkai-dai and @sherm1)

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include/fcl/narrowphase/detail/convexity_based_algorithm/gjk_libccd-inl.h, line 789 at r1 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

No change?

I guess my CLion doesn't autosave as much as I thought.

[sherm1]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[SeanCurtis-TRI]

@sherm1 this pr previously passed the appveyor CI. I had to rebase it because master moved (#321 merged). The appveyor CI has been queued for an hour. Shall we just go ahead and merge this?

Reviewable status: complete! all files reviewed, all discussions resolved