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Diffstat (limited to 'src/main/scala/sims/collision/Linear.scala')
| -rw-r--r-- | src/main/scala/sims/collision/Linear.scala | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/src/main/scala/sims/collision/Linear.scala b/src/main/scala/sims/collision/Linear.scala new file mode 100644 index 0000000..3c06515 --- /dev/null +++ b/src/main/scala/sims/collision/Linear.scala @@ -0,0 +1,67 @@ +/* _____ _ __ ________ ___ *\ +** / ___/(_) |/ / ___/ |__ \ Simple Mechanics Simulator 2 ** +** \__ \/ / /|_/ /\__ \ __/ / copyright (c) 2011 Jakob Odersky ** +** ___/ / / / / /___/ / / __/ ** +** /____/_/_/ /_//____/ /____/ ** +\* */ + +package sims.collision + +import scala.math._ +import sims.math._ + +/**A base trait for all linear geometric elements specified by one point and a direction. + * @throws IllegalArgumentException if the directional vector is the null vector*/ +trait Linear { + + /**A point contained in this linear element.*/ + val point: Vector2D + + /**Direction vector.*/ + val direction: Vector2D + + /**Unit directional vector.*/ + lazy val direction0 = direction.unit + + /**Right normal vector to <code>direction</code>.*/ + lazy val rightNormal = direction.rightNormal + + /**Right normal unit vector to <code>direction</code>.*/ + lazy val rightNormal0 = rightNormal.unit + + /**Left normal vector to <code>direction</code>.*/ + lazy val leftNormal = direction.leftNormal + + /**Left normal unit vector to <code>direction</code>.*/ + lazy val leftNormal0 = leftNormal.unit + + ///**Computes the closest point on this linear element to a given point.*/ + //def closest(point: Vector2D): Vector2D + + ///**Computes the shortest distance form this linear element to a given point.*/ + //def distance(point: Vector2D) = (closest(point) - point).length + + require(direction != 0, "A linear element's direction cannot be the null vector.") +} + +object Linear { + + /** Clips a segment passing through points `p1` and `p2` to a half plain + * given by a point `p` and a normal (pointing into the plain) `normal`. */ + def clip(p1: Vector2D, p2: Vector2D, p: Vector2D, normal: Vector2D): List[Vector2D] = { + val normal0 = normal.unit + val direction = p2 - p1 + + val d1 = (p1-p) dot normal0 + val d2 = (p2-p) dot normal0 + + if (d1 < 0 && d2 < 0) return Nil + if (d1 >= 0 && d2 >= 0) return List(p1, p2) + + val intersection = p1 + direction * abs(d1) / (abs(d1) + abs(d2)) + val inside = if (d1 > 0) p1 else p2 + + List(inside, intersection) + } + +}
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