Fix triangle distance

Author: schaumb

src/base/geom/line.h

@@ -19,7 +19,7 @@ struct Line
 
 	[[nodiscard]] bool isPoint() const { return begin == end; }
 
-	[[nodiscard]] Geom::Line extend(double length) const
+	[[nodiscard]] Line extend(double length) const
 	{
 		auto p = end - begin;
 		auto d = p.abs();
@@ -28,28 +28,28 @@ struct Line
 		return {begin, begin + (p * m)};
 	}
 
-	Geom::Line operator*(double value) const
+	Line operator*(double value) const
 	{
 		return {begin * value, end * value};
 	}
 
-	Geom::Line operator+(const Geom::Line &other) const
+	Line operator+(const Line &other) const
 	{
 		return {begin + other.begin, end + other.end};
 	}
 
-	void shift(const Geom::Point &offset)
+	void shift(const Point &offset)
 	{
 		begin = begin + offset;
 		end = end + offset;
 	}
 
-	[[nodiscard]] Geom::Point at(double t) const
+	[[nodiscard]] Point at(double t) const
 	{
 		return begin + (end - begin) * t;
 	}
 
-	[[nodiscard]] Geom::Line segment(double t0, double t1) const
+	[[nodiscard]] Line segment(double t0, double t1) const
 	{
 		return {at(t0), at(t1)};
 	}
@@ -63,7 +63,7 @@ struct Line
 	{
 		if (isPoint()) return (point - begin).abs();
 
-		auto projection = ((point - begin).dot(getDirection()))
+		auto projection = (point - begin).dot(getDirection())
 		                / (length() * length());
 
 		projection =

src/base/geom/triangle.cpp

@@ -1,5 +1,7 @@
 #include "triangle.h"
 
+#include <compare>
+
 #include "line.h"
 
 namespace Geom
@@ -14,20 +16,27 @@ double Triangle::area() const
 
 double Triangle::distance(const Point &point) const
 {
-	const auto A = points[2] - points[1];
-	const auto B = points[0] - points[1];
-	const auto C = points[2] - points[0];
-	const auto dA = Geom::Line{points[1], points[2]}.distance(point);
-	const auto dB = Geom::Line{points[0], points[1]}.distance(point);
-	const auto dC = Geom::Line{points[2], points[0]}.distance(point);
-	if (const auto double_area = fabs(A ^ B);
-	    !Math::Floating::is_zero(double_area)
-	    && Math::AddTolerance(
-	           A.abs() * dA + B.abs() * dB + C.abs() * dC)
-	           == double_area) {
+	auto rot_dir = [](const Point &a, const Point &b, const Point &c)
+	{
+		return std::weak_order(0.0,
+		    (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x));
+	};
+
+	using std::is_gteq;
+	using std::is_lteq;
+	using std::is_neq;
+	if (auto r1 = rot_dir(points[0], points[1], point),
+	    r2 = rot_dir(points[1], points[2], point),
+	    r3 = rot_dir(points[2], points[0], point);
+	    (is_neq(r1) || is_neq(r2) || is_neq(r3))
+	    && ((is_lteq(r1) && is_lteq(r2) && is_lteq(r3))
+	        || (is_gteq(r1) && is_gteq(r2) && is_gteq(r3))))
 		return 0.0;
-	}
-	return std::min({dA, dB, dC}, Math::Floating::less);
+
+	return std::min({Line{points[0], points[1]}.distance(point),
+	                    Line{points[1], points[2]}.distance(point),
+	                    Line{points[2], points[0]}.distance(point)},
+	    Math::Floating::less);
 }
 
 }