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engines/crab/Line.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/*
+ * This code is based on the CRAB engine
+ *
+ * Copyright (c) Arvind Raja Yadav
+ *
+ * Licensed under MIT
+ *
+ */
+
+#ifndef CRAB_LINE_H
+#define CRAB_LINE_H
+
+#include "crab/vectors.h"
+
+namespace Crab {
+
+// Find if 2 lines intersect and store the point of intersection
+template<typename T>
+bool collideLine(const T &p0X, const T &p0Y, const T &p1X, const T &p1Y,
+				 const T &p2X, const T &p2Y, const T &p3X, const T &p3Y,
+				 T *x = nullptr, T *y = nullptr) {
+	Vector2D<T> s1, s2;
+	s1.x = p1X - p0X;
+	s1.y = p1Y - p0Y;
+	s2.x = p3X - p2X;
+	s2.y = p3Y - p2Y;
+
+	float d = (-s2.x * s1.y + s1.x * s2.y);
+
+	if (d != 0) {
+		float s, t;
+		s = (-s1.y * (p0X - p2X) + s1.x * (p0Y - p2Y)) / d;
+		t = (s2.x * (p0Y - p2Y) - s2.y * (p0X - p2X)) / d;
+
+		if (s >= 0 && s <= 1 && t >= 0 && t <= 1) {
+			// Collision detected
+			if (x != nullptr)
+				*x = p0X + (t * s1.x);
+			if (y != nullptr)
+				*y = p0Y + (t * s1.y);
+
+			return true;
+		}
+	}
+
+	return false; // No collision
+}
+
+} // End of namespace Crab
+
+#endif // CRAB_LINE_H