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MATH: Refactor Line2d

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- use standard linear equation Ax + Bx = C
- simplify most calculations
- remove default constructor
- remove unused function
This commit is contained in:
Christian Krause 2014-10-05 02:58:59 +02:00 committed by Paweł Kołodziejski
parent f2195d8dbf
commit 082e792460
2 changed files with 26 additions and 48 deletions
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71
math/line2d.cpp
View File

@ -25,40 +25,29 @@
namespace Math {
Line2d::Line2d() :
_a(0), _b(0), _c(0) {
/* Linear equation used to describe the line:
*
* Ax + By = C
*
*/
}
Line2d::Line2d(const Vector2d &direction, const Vector2d &point) {
Vector2d d = direction;
if (fabsf(d.getX()) > 0.0001f) {
_a = d.getY() / d.getX();
_b = -1;
} else {
_a = 1;
_b = 0;
}
if (_b == 0) {
_c = -point.getX();
} else {
_c = point.getY() - (d.getY() / d.getX()) * point.getX();
}
_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 {
Vector2d v(1, _b / _a);
return Line2d(v, point);
return Line2d(Vector2d(_a, _b), point);
}
Vector2d Line2d::getDirection() const {
return Vector2d(1, _a);
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);
float dist = fabsf(_a * point.getX() + _b * point.getY() - _c) / sqrt(_a * _a + _b * _b);
if (intersection) {
intersectsLine(getPerpendicular(point), intersection);
@ -67,28 +56,24 @@ float Line2d::getDistanceTo(const Vector2d &point, Vector2d *intersection) const
}
bool Line2d::intersectsLine(const Line2d &line, Vector2d *pos) const {
// if (*this == line) {
// return false;
// }
float a1 = _a;
float b1 = _b;
float c1 = _c;
float a = _a;
float b = _b;
float c = _c;
float d = line._a;
float e = line._b;
float f = line._c;
float a2 = line._a;
float b2 = line._b;
float c2 = line._c;
float x, y;
const float det = a * e - b * d;
const float det = a1 * b2 - b1 * a2;
if (fabsf(det) < 0.0001f) {
if (fabsf(det) < epsilon) {
return false;
}
x = (-c * e + b * f) / det;
y = (-a * f + c * d) / det;
x = (c1 * b2 - c2 * b1) / det;
y = (a1 * c2 - a2 * c1) / det;
if (pos)
*pos = Vector2d(x, y);
@ -97,19 +82,15 @@ bool Line2d::intersectsLine(const Line2d &line, Vector2d *pos) const {
}
bool Line2d::containsPoint(const Vector2d &point) const {
float n = _a * point.getX() + _b * point.getY() + _c;
return (n < 0.0001 && n > -0.0001);
}
float Line2d::getYatX(float x) const {
return -(_a * x + _c) / _b;
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) < 0.0001f) {
dbg.nospace() << "Line2d: <y = " << (-line._a / line._b) << " * x + " << -line._c / line._b << ">";
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 << ">";
dbg.nospace() << "Line2d: <x = " << (-line._b / line._a) << " * y + " << line._c / line._a << ">";
}
return dbg.space();

3
math/line2d.h
View File

@ -29,7 +29,6 @@ namespace Math {
class Line2d {
public:
Line2d();
Line2d(const Vector2d &direction, const Vector2d &point);
Line2d getPerpendicular(const Vector2d &point = Vector2d()) const;
@ -39,8 +38,6 @@ public:
bool intersectsLine(const Line2d &line, Vector2d *pos) const;
bool containsPoint(const Vector2d &point) const;
float getYatX(float x) const;
friend Common::StreamDebug &operator<<(Common::StreamDebug &dbg, const Line2d &line);
private: