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Merge pull request #66 from brandonw/master

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Add line segment shape and functions
This commit is contained in:
Brendan Zabarauskas 2014-05-13 19:35:39 -07:00
commit d9967b3f1c
4 changed files with 202 additions and 0 deletions
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1
src/cgmath/lib.rs
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@ -30,6 +30,7 @@ pub mod vector;
pub mod angle;
pub mod plane;
pub mod point;
pub mod line;
pub mod ray;
pub mod rotation;
pub mod transform;

121
src/cgmath/line.rs Normal file
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@ -0,0 +1,121 @@
// Copyright 2013 The CGMath Developers. For a full listing of the authors,
// refer to the AUTHORS file at the top-level directionectory of this distribution.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! Line segments
use std::num::{Zero, zero, One, one};
use point::{Point, Point2, Point3};
use vector::{Vector, Vector2};
use partial_ord::PartOrdFloat;
use intersect::Intersect;
/// A generic directed line segment
#[deriving(Clone, Eq)]
pub struct Line<P>
{
pub origin: P,
pub dest: P,
}
impl
<
S: Primitive,
Slice,
V: Vector<S,Slice>,
P: Point<S,V,Slice>
> Line<P>
{
pub fn new(origin: P, dest: P) -> Line<P> {
Line { origin:origin, dest:dest }
}
}
pub type Line2<S> = Line<Point2<S>>;
pub type Line3<S> = Line<Point3<S>>;
/// Determines if an intersection between two line segments is found. If the segments are
/// collinear and overlapping, the intersection point that will be returned will be the first
/// intersection point found by traversing the first line segment, starting at its origin.
impl<S: PartOrdFloat<S>> Intersect<Option<Point2<S>>> for (Line2<S>, Line2<S>) {
fn intersection(&self) -> Option<Point2<S>> {
match *self {
(ref l1, ref l2) => {
let p = l1.origin;
let mut q = l2.origin;
let r = Vector2::new(l1.dest.x - l1.origin.x, l1.dest.y - l1.origin.y);
let mut s = Vector2::new(l2.dest.x - l2.origin.x, l2.dest.y - l2.origin.y);
let zero: S = Zero::zero();
let cross = r.perp_dot(&s);
let mut q_minus_p = Vector2::new(q.x - p.x, q.y - p.y);
let mut p_minus_q = Vector2::new(p.x - q.x, p.y - q.y);
let cross_r = q_minus_p.perp_dot(&r);
let cross_s = q_minus_p.perp_dot(&s);
if cross.is_zero() {
if cross_r.is_zero() {
// line segments are collinear
// special case of both lines being the same single point
if r.x == zero && r.y == zero && s.x == zero && s.y == zero && p == q {
return Some(p);
}
// ensure l2 (q,q+s) is pointing the same direction as l1 (p,p+r)
// if it is not, then swap the two endpoints of the second segment.
// If this is not done, the algorithm below will not find an
// intersection if the two directed line segments point towards the
// opposite segment's origin.
if (r.x != zero && s.x != zero && r.x.signum() != s.x.signum()) ||
(r.y != zero && s.y != zero && r.y.signum() != s.y.signum()) {
q = Point2::new(q.x + s.x, q.y + s.y);
s = Vector2::new(-s.x, -s.y);
q_minus_p = Vector2::new(q.x - p.x, q.y - p.y);
p_minus_q = Vector2::new(p.x - q.x, p.y - q.y);
}
let d1 = q_minus_p.dot(&r);
let d2 = p_minus_q.dot(&s);
let rdotr = r.dot(&r);
let sdots = s.dot(&s);
// make sure to take into account that one or both of the segments could
// be a single point (r.r or s.s = 0) and ignore that case
if (rdotr > zero && zero <= d1 && d1 <= rdotr) ||
(sdots > zero && zero <= d2 && d2 <= sdots) {
// overlapping
if (q_minus_p.x != zero && q_minus_p.x.signum() == r.x.signum()) ||
(q_minus_p.y != zero && q_minus_p.y.signum() == r.y.signum()) {
return Some(q);
}
return Some(p);
}
}
return None;
}
let t = cross_s / cross;
let u = cross_r / cross;
if zero <= t && t <= One::one() &&
zero <= One::one() && u <= One::one() {
return Some(Point2::new(p.x + t*r.x, p.y + t*r.y));
}
return None;
}
}
}
}

79
src/test/line.rs Normal file
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@ -0,0 +1,79 @@
// Copyright 2013 The CGMath Developers. For a full listing of the authors,
// refer to the AUTHORS file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use cgmath::line::*;
use cgmath::point::*;
use cgmath::intersect::Intersect;
#[test]
fn test_line_intersection() {
// collinear, origins pointing towards each other, first intersection
// from l1.origin is in an endpoint in l2
let l1 = Line::new(Point2::new(0.0, 0.0), Point2::new(10.0, 0.0));
let l2 = Line::new(Point2::new(1.5, 0.0), Point2::new(0.5, 0.0));
assert_eq!((l1, l2).intersection(), Some(Point2::new(0.5, 0.0)));
// collinear, first intersection from p1.origin is at p1.origin itself
let l3 = Line::new(Point2::new(0.0, 0.0), Point2::new(10.0, 0.0));
let l4 = Line::new(Point2::new(-11.0, 0.0), Point2::new(1.0, 0.0));
assert_eq!((l3, l4).intersection(), Some(Point2::new(0.0, 0.0)));
// no intersection
let l5 = Line::new(Point2::new(5.0, 5.0), Point2::new(10.0, 6.0));
let l6 = Line::new(Point2::new(5.0, 4.8), Point2::new(10.0, 4.1));
assert_eq!((l5, l6).intersection(), None); // no intersection
// collinear, origins pointing same direction
let l7 = Line::new(Point2::new(0.0, 1.0), Point2::new(0.0, 0.0));
let l8 = Line::new(Point2::new(0.0, 0.5), Point2::new(0.0, -0.5));
assert_eq!((l7, l8).intersection(), Some(Point2::new(0.0, 0.5)));
// collinear, no overlap
let l9 = Line::new(Point2::new(0.0, 0.0), Point2::new(3.0, 0.0));
let l10 = Line::new(Point2::new(10.0, 0.0), Point2::new(5.0, 0.0));
assert_eq!((l9, l10).intersection(), None);
// intersection found
let l11 = Line::new(Point2::new(0.0, 0.0), Point2::new(10.0, 10.0));
let l12 = Line::new(Point2::new(0.0, 10.0), Point2::new(10.0, 0.0));
assert_eq!((l11, l12).intersection(), Some(Point2::new(5.0, 5.0)));
// special case of both lines being the same point
let l13 = Line::new(Point2::new(0.0, 0.0), Point2::new(0.0, 0.0));
let l14 = Line::new(Point2::new(0.0, 0.0), Point2::new(0.0, 0.0));
assert_eq!((l13, l14).intersection(), Some(Point2::new(0.0, 0.0)));
// both lines are points that are distinct
let l15 = Line::new(Point2::new(0.0, 0.0), Point2::new(0.0, 0.0));
let l16 = Line::new(Point2::new(1.0, 0.0), Point2::new(1.0, 0.0));
assert_eq!((l15, l16).intersection(), None);
// one line is a point that intersects the other segment
let l15 = Line::new(Point2::new(0.0, 0.0), Point2::new(10.0, 0.0));
let l16 = Line::new(Point2::new(3.0, 0.0), Point2::new(3.0, 0.0));
assert_eq!((l15, l16).intersection(), Some(Point2::new(3.0, 0.0)));
// one line is a point that is collinear but does not intersect with
// the other line
let l17 = Line::new(Point2::new(0.0, 0.0), Point2::new(0.0, 0.0));
let l18 = Line::new(Point2::new(1.0, 0.0), Point2::new(3.0, 0.0));
assert_eq!((l17, l18).intersection(), None);
// one line is a point that is not collinear but does not intersect
// with the other line
let l19 = Line::new(Point2::new(0.0, 0.0), Point2::new(0.0, 0.0));
let l20 = Line::new(Point2::new(1.0, 0.0), Point2::new(2.0, 10.0));
assert_eq!((l19, l20).intersection(), None);
}

1
src/test/test.rs
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@ -26,6 +26,7 @@ pub mod vector;
pub mod angle;
pub mod plane;
pub mod point;
pub mod line;
// pub mod ray;
// pub mod rotation;
pub mod transform;