Definition
An instance r of the data type ray is a directed straight ray in the two-dimensional plane. The angle between a right oriented horizontal ray and r is called the direction of r.
Creation
| ray | r(point p, point q); | introduces a variable r of type ray. r is initialized to the ray starting at point p and passing through point q. |
ray |
r(segment s); | introduces a variable r of type ray. r is initialized to ray(s.source(),s.target()). |
ray |
r(point p, vector v); | introduces a variable r of type ray. r is initialized to ray(p,p+v). |
ray |
r(point p, double alpha); | introduces a variable r of type ray. r is initialized to the ray starting at point p with direction alpha. |
ray |
r; | introduces a variable r of type ray. r is initialized to the ray starting at the origin with direction 0. |
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Operations
| point | r.source() | returns the source of r. |
| point | r.point1() | returns the source of r. |
| point | r.point2() | returns a point on r different from r.source(). |
| double | r.direction() | returns the direction of r. |
| double | r.angle(ray s) | returns the angle between r and s, i.e., s.direction() - r.direction(). |
| bool | r.is_vertical() | returns true iff r is vertical. |
| bool | r.is_horizontal() | returns true iff r is horizontal. |
| double | r.slope() | returns the slope of r.
Precondition: r is not vertical. |
| bool | r.intersection(ray s, point& inter) | |
| if r and s intersect in a single point this point is assigned to inter and the result is true, otherwise the result is false. | ||
| bool | r.intersection(segment s, point& inter) | |
| if r and s intersect in a single point this point is assigned to inter and the result is true, otherwise the result is false. | ||
| ray | r.translate_by_angle(double a, double d) | |
| returns r translated in direction a by distance d. | ||
| ray | r.translate(double dx, double dy) | |
| returns r translated by vector (dx,dy). | ||
| ray | r.translate(vector v) | returns r translated by vector v
Precondition: v.dim() = 2. |
| ray | r + vector v | returns r translated by vector v. |
| ray | r - vector v | returns r translated by vector -v. |
| ray | r.rotate(point q, double a) | |
| returns r rotated about point q by angle a. | ||
| ray | r.rotate(double a) | returns r.rotate(point(0,0), a). |
| ray | r.rotate90(point q) | returns r rotated about q by angle of 90 degrees. |
| ray | r.reflect(point p, point q) | |
| returns r reflected across the straight line passing through p and q. | ||
| ray | r.reflect(point p) | returns r reflected across point p. |
| ray | r.reverse() | returns r reversed. |
| bool | r.contains(point) | decides whether r contains p. |
| bool | r.contains(segment) | decides whether r contains s. |
Non-Member Functions
| int | orientation(ray r, point p) | |
| computes orientation(a, b, p), where a != b and a and b appear in this order on ray r. | ||
| int | cmp_slopes(ray r1, ray r2) | |
| returns compare(slope(r_1), slope(r_2)). | ||