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Added point_in_triangle function.

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This commit is contained in:
James.Hester 2019-11-12 07:55:09 +11:00
parent 9ac3c1a394
commit b91d4411b5
1 changed files with 23 additions and 0 deletions
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23
simgear/math/SGVec2.hxx
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@ -375,6 +375,29 @@ interpolate(T tau, const SGVec2<T>& v1, const SGVec2<T>& v2)
return r; return r;
} }
// Is the first point inside the triangle formed by the other three points?
// Helper function
template <typename T>
inline
T
pt_determine(const SGVec2<T>& pt1, const SGVec2<T>& pt2, const SGVec2<T>& pt3)
{
return (pt1.x()-pt3.x()) * (pt2.y()-pt3.y()) - (pt2.x() - pt3.x()) * (pt1.y() - pt3.y());
}
template <typename T>
inline
bool
point_in_triangle(const SGVec2<T>& testpt, const SGVec2<T>& pt1, const SGVec2<T>& pt2, const SGVec2<T>& pt3)
{
T d1 = pt_determine(testpt,pt1,pt2);
T d2 = pt_determine(testpt,pt2,pt3);
T d3 = pt_determine(testpt,pt3,pt1);
bool has_neg = (d1 < 0) || (d2 < 0) || (d3 < 0);
bool has_pos = (d1 > 0) || (d2 > 0) || (d3 > 0);
return !(has_neg && has_pos);
}
#ifndef NDEBUG #ifndef NDEBUG
template<typename T> template<typename T>
inline inline