std/geometry/ray2
std/geometry/src/ray2.trb
Ray2, the half-line in the plane, and the hit tests written against it: the shape a pick, a line of sight and a
one-step sweep are all asked in terms of.
type Ray2
type Ray2<Scalar: Real = Float>A half-line: where it starts and which way it points.
Every hit test answers how far along the ray the hit is, as a distance in the length of direction, and not the
point itself: a caller that wants the nearest of several hits compares those numbers, and a caller that wants the
point asks Ray2.at for it. A direction of length one therefore makes every answer a distance.
Examples
const look = Ray2 Vector2(0.0, 0.0), Vector2(1.0, 0.0)
print look.hits(Circle(Vector2(5.0, 0.0), 1.0))
Pitfalls
- A
directionof zero has no hits at all, and every test answersNonefor it rather than panicking. - A ray that starts inside a shape answers
0, not the exit distance. A caller that wants the exit asks the shape.
Related
Segment2- the piece of line with two ends.Ray3- the same in space.
field origin
origin: Vector2<Scalar>Where the ray starts.
field direction
direction: Vector2<Scalar>Which way it points. The hit distances are measured in this vector's length.
fn towards
static fn towards(from: Vector2<Scalar>, to: Vector2<Scalar>): Ray2<Scalar>The ray from one point towards another, with a direction of length one.
fn at
fn at(distance: Scalar): Vector2<Scalar>The point that far along the ray. A negative distance reads backwards, behind the origin.
fn hits
fn hits(circle: Circle<Scalar>): Scalar?How far along the ray the disc is first met, or None where the ray misses it. A ray that starts inside answers
zero.
fn hitsRectangle
fn hitsRectangle(rectangle: Rectangle<Scalar>): Scalar?How far along the ray the rectangle is first met, or None where the ray misses it. This is the slab test: the ray
enters the rectangle where the last axis lets it in and leaves where the first axis shuts it out.
fn hitsSegment
fn hitsSegment(segment: Segment2<Scalar>): Scalar?How far along the ray the segment is met, or None where the ray misses it.