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math/line2d.cpp

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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/>.
+ *
+ */
+
+#include "math/line2d.h"
+#include "math/rect2d.h"
+
+namespace Math {
+
+/* Linear equation used to describe the line:
+ *
+ * Ax + By = C
+ *
+ */
+
+Line2d::Line2d(const Vector2d &direction, const Vector2d &point) {
+	_a = direction.getX();
+	_b = direction.getY();
+	_c = point.getY() * (point.getX() + direction.getX()) - point.getX() * (point.getY() + direction.getY());
+}
+
+Line2d Line2d::getPerpendicular(const Vector2d &point) const {
+	return Line2d(Vector2d(_a, _b), point);
+}
+
+Vector2d Line2d::getDirection() const {
+	return Vector2d(-_b, _a);
+}
+
+float Line2d::getDistanceTo(const Vector2d &point, Vector2d *intersection) const {
+	float dist = fabsf(_a * point.getX() + _b * point.getY() - _c) / sqrt(_a * _a + _b * _b);
+
+	if (intersection) {
+		intersectsLine(getPerpendicular(point), intersection);
+	}
+	return dist;
+}
+
+bool Line2d::intersectsLine(const Line2d &line, Vector2d *pos) const {
+	float a1 = _a;
+	float b1 = _b;
+	float c1 = _c;
+
+	float a2 = line._a;
+	float b2 = line._b;
+	float c2 = line._c;
+
+	float x, y;
+
+	const float det = a1 * b2 - b1 * a2;
+
+	if (fabsf(det) < epsilon) {
+		return false;
+	}
+
+	x = (c1 * b2 - c2 * b1) / det;
+	y = (a1 * c2 - a2 * c1) / det;
+
+	if (pos)
+		*pos = Vector2d(x, y);
+
+	return true;
+}
+
+bool Line2d::containsPoint(const Vector2d &point) const {
+	float n = _a * point.getX() + _b * point.getY() - _c;
+	return (fabsf(n) < epsilon);
+}
+
+Common::StreamDebug &operator<<(Common::StreamDebug &dbg, const Math::Line2d &line) {
+	if (fabsf(line._a) < epsilon) {
+		dbg.nospace() << "Line2d: <y = " << (-line._a / line._b) << " * x + " << line._c / line._b << ">";
+	} else {
+		dbg.nospace() << "Line2d: <x = " << (-line._b / line._a) << " * y + " << line._c / line._a << ">";
+	}
+
+	return dbg.space();
+}
+
+
+Segment2d::Segment2d() {
+}
+
+Segment2d::Segment2d(const Vector2d &b, const Vector2d &e) :
+	_begin(b), _end(e) {
+}
+
+Segment2d::Segment2d(const Segment2d &other) {
+	*this = other;
+}
+
+Vector2d Segment2d::begin() const {
+	return _begin;
+}
+
+Vector2d Segment2d::end() const {
+	return _end;
+}
+
+Vector2d Segment2d::middle() const {
+	return (_begin + _end) / 2.f;
+}
+
+Line2d Segment2d::getLine() const {
+	float y = _end.getY() - _begin.getY();
+	float x = _end.getX() - _begin.getX();
+	Vector2d v(x, y);
+
+	return Line2d(v, _begin);
+}
+
+Line2d Segment2d::getPerpendicular(const Vector2d &point) const {
+	return getLine().getPerpendicular(point);
+}
+
+bool Segment2d::intersectsSegment(const Segment2d &other, Vector2d *pos) {
+	float denom = ((other._end.getY() - other._begin.getY()) * (_end.getX() - _begin.getX())) -
+	((other._end.getX() - other._begin.getX()) * (_end.getY() - _begin.getY()));
+
+
+	float d = ((_end.getY() - _begin.getY()) * (other._end.getX() - other._begin.getX())) -
+	((_end.getX() - _begin.getX()) * (other._end.getY() - other._begin.getY()));
+
+	float nume_a = ((other._end.getX() - other._begin.getX()) * (_begin.getY() - other._begin.getY())) -
+	((other._end.getY() - other._begin.getY()) * (_begin.getX() - other._begin.getX()));
+
+	float nume_b = ((_end.getX() - _begin.getX()) * (other._begin.getY() - _begin.getY())) -
+	((_end.getY() - _begin.getY()) * (other._begin.getX() - _begin.getX()));
+
+	if (denom == 0.0f || d == 0.0f ) {
+		return false;
+	}
+
+	float ua = nume_a / denom;
+	float ub = nume_b / d;
+
+	if (ua < 0.0f || ua > 1.0f || ub < 0.0f || ub > 1.0f) {
+		return false;
+	}
+
+	// Get the intersection point.
+	if (pos)
+		*pos = _begin + (_end - _begin) * ua;
+
+	return true;
+}
+
+bool Segment2d::intersectsLine(const Line2d &line, Vector2d *pos) {
+	Vector2d p;
+	if (getLine().intersectsLine(line, &p) && containsPoint(p)) {
+		if (pos)
+			*pos = p;
+		return true;
+	}
+
+	return false;
+}
+
+bool Segment2d::containsPoint(const Vector2d &point) const {
+	if (getLine().containsPoint(point)) {
+		return Rect2d(_begin, _end).containsPoint(point);
+	}
+
+	return false;
+}
+
+Segment2d &Segment2d::operator=(const Segment2d &other) {
+	_begin = other._begin;
+	_end = other._end;
+
+	return *this;
+}
+
+}