[Geometry] Bugfixes and add unit tests#5987
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fredroy wants to merge 9 commits intosofa-framework:masterfrom
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[Geometry] Bugfixes and add unit tests#5987fredroy wants to merge 9 commits intosofa-framework:masterfrom
fredroy wants to merge 9 commits intosofa-framework:masterfrom
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fredroy
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bakpaul
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| // In 3D, use signed areas via dot product with triangle normal | ||
| // to get correct sign for outside-triangle points | ||
| const auto N = sofa::type::cross(n1 - n0, n2 - n0); | ||
| const auto NdotN = sofa::type::dot(N, N); | ||
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| if (NdotN < std::numeric_limits<T>::epsilon() * std::numeric_limits<T>::epsilon()) // triangle is flat | ||
| { | ||
| return sofa::type::Vec<3, T>(-1, -1, -1); | ||
| } | ||
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| sofa::type::Vec<3, T> baryCoefs(type::NOINIT); | ||
| baryCoefs[0] = sofa::type::dot(N, sofa::type::cross(n2 - n1, p0 - n1)) / NdotN; | ||
| baryCoefs[1] = sofa::type::dot(N, sofa::type::cross(n0 - n2, p0 - n2)) / NdotN; | ||
| baryCoefs[2] = 1 - baryCoefs[0] - baryCoefs[1]; | ||
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| if (fabs(baryCoefs[2]) <= std::numeric_limits<T>::epsilon()){ | ||
| baryCoefs[2] = 0; | ||
| } | ||
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| return baryCoefs; |
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Ok, before this the barycentric mapping was a bit wrong when the point wasn't on the triangle. Because of 104, the value of the third barycentric coordinate was always underestimated because the other ones where overestimated.
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@epernod this fix the cases when the point is not on the same plane as the triangle. But does it ever happen ? Anyway I think that the api should not expect anything and check because otherwise we would rely on the user to make the check before.
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if (denominator < EQUALITY_THRESHOLD) the denominator is a signed dot product. When negative (edge crosses plane from the "back"), this is always true, so the function rejects ~half of all valid intersections.
1-The 2D path computes alpha (parameter on edge AB) and checks 0 <= alpha <= 1, but never computes or checks beta (parameter on edge CD). Reports false intersections when the infinite line CD crosses segment AB but outside segment CD. 2-if (alphaDenom < std::numeric_limits<T>::epsilon()) same pattern as Bug 1. The cross product alphaDenom is signed. When negative (non-collinear edges in one orientation), incorrectly reports them as collinear.
solveLCP returns true when solver fails to converge (max iterations reached)
While isPointInTriangle still works (it only checks sign pattern), any code that uses the returned coordinates for interpolation, projection to the nearest point on the triangle, or distance computation gets wrong values. This is a public utility function likely consumed by many parts of the codebase.
…o bypass the plane check (as before)
…or for beta) Co-authored-by: Paul Baksic <30337881+bakpaul@users.noreply.github.com>
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Fix various Edge and triangles functions
and more unit tests for Sofa.Geometry module
[with-all-tests]
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