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194 lines
4.8 KiB
C++
194 lines
4.8 KiB
C++
/* ResidualVM - A 3D game interpreter
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*
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* ResidualVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include "math/line2d.h"
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#include "math/rect2d.h"
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namespace Math {
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/* Linear equation used to describe the line:
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*
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* Ax + By = C
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*
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*/
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Line2d::Line2d(const Vector2d &direction, const Vector2d &point) {
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_a = direction.getX();
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_b = direction.getY();
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_c = point.getY() * (point.getX() + direction.getX()) - point.getX() * (point.getY() + direction.getY());
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}
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Line2d Line2d::getPerpendicular(const Vector2d &point) const {
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return Line2d(Vector2d(_a, _b), point);
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}
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Vector2d Line2d::getDirection() const {
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return Vector2d(-_b, _a);
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}
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float Line2d::getDistanceTo(const Vector2d &point, Vector2d *intersection) const {
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float dist = fabsf(_a * point.getX() + _b * point.getY() - _c) / sqrt(_a * _a + _b * _b);
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if (intersection) {
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intersectsLine(getPerpendicular(point), intersection);
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}
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return dist;
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}
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bool Line2d::intersectsLine(const Line2d &line, Vector2d *pos) const {
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float a1 = _a;
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float b1 = _b;
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float c1 = _c;
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float a2 = line._a;
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float b2 = line._b;
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float c2 = line._c;
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float x, y;
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const float det = a1 * b2 - b1 * a2;
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if (fabsf(det) < epsilon) {
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return false;
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}
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x = (c1 * b2 - c2 * b1) / det;
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y = (a1 * c2 - a2 * c1) / det;
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if (pos)
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*pos = Vector2d(x, y);
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return true;
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}
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bool Line2d::containsPoint(const Vector2d &point) const {
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float n = _a * point.getX() + _b * point.getY() - _c;
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return (fabsf(n) < epsilon);
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}
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Common::StreamDebug &operator<<(Common::StreamDebug &dbg, const Math::Line2d &line) {
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if (fabsf(line._a) < epsilon) {
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dbg.nospace() << "Line2d: <y = " << (-line._a / line._b) << " * x + " << line._c / line._b << ">";
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} else {
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dbg.nospace() << "Line2d: <x = " << (-line._b / line._a) << " * y + " << line._c / line._a << ">";
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}
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return dbg.space();
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}
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Segment2d::Segment2d() {
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}
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Segment2d::Segment2d(const Vector2d &b, const Vector2d &e) :
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_begin(b), _end(e) {
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}
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Segment2d::Segment2d(const Segment2d &other) {
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*this = other;
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}
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Vector2d Segment2d::begin() const {
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return _begin;
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}
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Vector2d Segment2d::end() const {
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return _end;
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}
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Vector2d Segment2d::middle() const {
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return (_begin + _end) / 2.f;
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}
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Line2d Segment2d::getLine() const {
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float y = _end.getY() - _begin.getY();
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float x = _end.getX() - _begin.getX();
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Vector2d v(x, y);
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return Line2d(v, _begin);
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}
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Line2d Segment2d::getPerpendicular(const Vector2d &point) const {
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return getLine().getPerpendicular(point);
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}
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bool Segment2d::intersectsSegment(const Segment2d &other, Vector2d *pos) {
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float denom = ((other._end.getY() - other._begin.getY()) * (_end.getX() - _begin.getX())) -
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((other._end.getX() - other._begin.getX()) * (_end.getY() - _begin.getY()));
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float d = ((_end.getY() - _begin.getY()) * (other._end.getX() - other._begin.getX())) -
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((_end.getX() - _begin.getX()) * (other._end.getY() - other._begin.getY()));
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float nume_a = ((other._end.getX() - other._begin.getX()) * (_begin.getY() - other._begin.getY())) -
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((other._end.getY() - other._begin.getY()) * (_begin.getX() - other._begin.getX()));
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float nume_b = ((_end.getX() - _begin.getX()) * (other._begin.getY() - _begin.getY())) -
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((_end.getY() - _begin.getY()) * (other._begin.getX() - _begin.getX()));
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if (denom == 0.0f || d == 0.0f ) {
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return false;
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}
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float ua = nume_a / denom;
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float ub = nume_b / d;
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if (ua < 0.0f || ua > 1.0f || ub < 0.0f || ub > 1.0f) {
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return false;
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}
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// Get the intersection point.
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if (pos)
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*pos = _begin + (_end - _begin) * ua;
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return true;
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}
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bool Segment2d::intersectsLine(const Line2d &line, Vector2d *pos) {
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Vector2d p;
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if (getLine().intersectsLine(line, &p) && containsPoint(p)) {
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if (pos)
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*pos = p;
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return true;
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}
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return false;
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}
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bool Segment2d::containsPoint(const Vector2d &point) const {
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if (getLine().containsPoint(point)) {
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return Rect2d(_begin, _end).containsPoint(point);
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}
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return false;
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}
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Segment2d &Segment2d::operator=(const Segment2d &other) {
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_begin = other._begin;
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_end = other._end;
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return *this;
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}
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}
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