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Diffstat (limited to 'src/main/scala/sims/collision/ConvexPolygon.scala')
| -rw-r--r-- | src/main/scala/sims/collision/ConvexPolygon.scala | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/src/main/scala/sims/collision/ConvexPolygon.scala b/src/main/scala/sims/collision/ConvexPolygon.scala new file mode 100644 index 0000000..3d7a81b --- /dev/null +++ b/src/main/scala/sims/collision/ConvexPolygon.scala @@ -0,0 +1,60 @@ +/* _____ _ __ ________ ___ *\ +** / ___/(_) |/ / ___/ |__ \ Simple Mechanics Simulator 2 ** +** \__ \/ / /|_/ /\__ \ __/ / copyright (c) 2011 Jakob Odersky ** +** ___/ / / / / /___/ / / __/ ** +** /____/_/_/ /_//____/ /____/ ** +\* */ + +package sims.collision + +import sims.math._ + +/** Common properties of all convex polygons. + * '''Note: convex polygons are not verified to be convex. It is up to the client to ensure this.''' */ +trait ConvexPolygon extends Polygon { + + /**Returns the projection of this polygon onto the line given by the directional vector <code>axis</code>. + * @param axis directional vector of the line + * @return projection of this polygon*/ + override def project(axis: Vector2D) = { + val dir = axis.unit + var min = vertices(0) dot dir + var max = vertices(0) dot dir + + for (v <- vertices) { + val d = v dot dir + if (d < min) min = d + if (d > max) max = d + } + + new Projection(axis, min, max) + } + + /**Checks if the point <code>point</code> is contained in this polygon. + * <p> + * A ray is created, originating from the point and following an arbitrary direction (X-Axis was chosen). + * The number of intersections between the ray and this polygon's sides (including vertices) is counted. + * The amount of intersections with vertices is subtracted form the previous number. + * If the latter number is odd, the point is contained in the polygon.*/ + override def contains(point: Vector2D) = { + val r = new Ray(point, Vector2D.i) + var intersections = 0 + for (s <- sides; if !(r intersection s).isEmpty) intersections += 1 + for (v <- vertices; if (r contains v)) intersections -= 1 + intersections % 2 != 0 + } + + override def support(direction: Vector2D) = { + var maxDistance = vertices(0) dot direction + var maxPoint = vertices(0) + for (v <- vertices) { + val s = v dot direction + if (s > maxDistance) { + maxDistance = s + maxPoint = v + } + } + maxPoint + } + +}
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