From 01c5c700647feba596e02cb7a2e672f5301504ff Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jodersky@gmail.com>
Date: Mon, 29 Jun 2015 12:32:00 +0200
Subject: Port to scala 2.11

---
 src/main/scala/sims/collision/GridDetector.scala | 123 +++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 src/main/scala/sims/collision/GridDetector.scala

(limited to 'src/main/scala/sims/collision/GridDetector.scala')

diff --git a/src/main/scala/sims/collision/GridDetector.scala b/src/main/scala/sims/collision/GridDetector.scala
new file mode 100644
index 0000000..2196195
--- /dev/null
+++ b/src/main/scala/sims/collision/GridDetector.scala
@@ -0,0 +1,123 @@
+/*
+ * Simple Mechanics Simulator (SiMS)
+ * copyright (c) 2009 Jakob Odersky
+ * made available under the MIT License
+*/
+
+package sims.collision
+
+import sims.dynamics._
+import sims.geometry._
+import scala.collection._
+import scala.collection.mutable.ArrayBuffer
+import scala.collection.mutable.HashMap
+
+/**A concrete implementation of <code>Detector</code>. <code>GridDetector</code> divides the world into a grid
+ * for faster collision detection.*/
+class GridDetector(override val world: World) extends Detector {
+  
+  /**Array of collision detection methods. These methods return <code>true</code> if two shapes are colliding.*/
+  val detectionMethods = new ArrayBuffer[PartialFunction[(Shape, Shape), Boolean]]
+  detectionMethods += {
+    case (c1: Circle, c2: Circle) => {	//collision if distance <= sum of radiuses
+      val d = (c1.pos - c2.pos).length
+      val rSum = c1.radius + c2.radius
+      d - rSum <= 0
+      }
+    
+    case (p1: ConvexPolygon, p2: ConvexPolygon) => {	//SAT
+      val sides = p1.sides ++ p2.sides
+      val axes = sides map (_.n0)
+      axes.forall((a: Vector2D) => p1.project(a) overlaps p2.project(a))
+    }
+    
+    case (p: ConvexPolygon, c: Circle) => {	//distance form center to sides or vertices
+      val distances = for (s <- p.sides) yield (s distance c.pos)
+      distances.exists(_ - c.radius <= 0) || (p contains c.pos)
+      }
+    
+    case (c: Circle, p: ConvexPolygon) => {	//distance form center to sides or vertices
+      val distances = for (s <- p.sides) yield (s distance c.pos)
+      distances.exists(_ - c.radius <= 0) || (p contains c.pos)
+      }
+  }
+  
+   /**Array of methods returning collisions. It is assumed that both shapes are colliding.*/
+  val collisionMethods = new ArrayBuffer[PartialFunction[(Shape, Shape), Collision]]
+  collisionMethods += {
+    case (c1: Circle, c2: Circle) => CircleCollision(c1, c2)
+    case (p1: ConvexPolygon, p2: ConvexPolygon) => PolyCollision(p1, p2)
+    case (p: ConvexPolygon, c: Circle) => PolyCircleCollision(p, c)
+    case (c: Circle, p: ConvexPolygon) => PolyCircleCollision(p, c)
+  }
+  
+  /**Checks the pair of shapes <code>p</code> for collision.
+   * @param p Pair of shapes.*/
+  def colliding(p: Pair) = {
+   if (detectionMethods.exists(_.isDefinedAt(p))) 
+     detectionMethods.find(_.isDefinedAt(p)).get.apply(p)
+    else throw new IllegalArgumentException("No collision method for colliding pair!")
+  }
+  
+  /**Returns the collision between both shapes of the pair <code>p</code>.
+   * @param p Pair of shapes.*/
+  def collision(p: Pair): Collision = {
+    if (collisionMethods.exists(_.isDefinedAt(p)))
+      collisionMethods.find(_.isDefinedAt(p)).get.apply(p)
+    else throw new IllegalArgumentException("No collision found in colliding pair!")
+  }
+  
+  /**Width and height of a grid cell.*/
+  var gridSide: Double = 2
+  
+  /**Returns potential colliding pairs of shapes of the world <code>world</code>.
+   * <p>
+   * A potential colliding pair is a pair of two shapes that comply with the following criteria:
+   * <ul>
+   * <li>The shapes are situated in the same grid cell.</li>
+   * <li>Their AABBs overlap.</li>
+   * <li>The shapes do not belong to the same body.</li>
+   * <li>At least one shape is not fixed.</li>
+   * <li>Both shapes are {@link dynamics.Shape#collidable}.</li>
+   * </ul>*/
+  def getPairs = {
+    val grid = new HashMap[(Int, Int), List[Shape]]
+    def gridCoordinates(v: Vector2D) = ((v.x / gridSide).toInt, (v.y / gridSide).toInt)
+    def addToGrid(s: Shape) = {
+      val aabb = s.AABB  
+      val minCell = gridCoordinates(aabb.minVertex)
+      val maxCell = gridCoordinates(aabb.maxVertex)
+      val coords = for(i <- (minCell._1 to maxCell._1); j <- (minCell._2 to maxCell._2)) yield (i, j)
+      for (c <- coords) {
+        if (grid.contains(c))
+          {if (grid(c).forall(_ ne s)) grid(c) = s :: grid(c)}
+        else
+            grid += (c -> List(s))
+      	}
+      }
+    for(s <- world.shapes) addToGrid(s)
+    var ps: List[Pair] = Nil
+    for(cell <- grid.valuesIterator) {
+      ps = ps ::: (for (s1: Shape <- cell; s2: Shape <- cell;
+                    if (s1 ne s2);                       
+           			if (s1.body ne s2.body);
+           			if (s1.collidable && s2.collidable);
+                    if (s1.AABB overlaps s2.AABB);
+                    if (!s1.transientShapes.contains(s2) && !s2.transientShapes.contains(s1))) yield Pair(s1, s2)
+       				).distinct
+    }
+    ps.toSeq
+  }
+  
+  private var cache = (world.time, getPairs)
+  
+  /**All potential colliding pairs of the world.
+   * @see getPairs*/
+  def pairs = {if (world.time != cache._1) cache = (world.time, getPairs); cache._2}
+  
+  /**Returns all colliding pairs.*/
+  def collidingPairs: Seq[Pair] = for(p <- pairs; if (colliding(p))) yield p
+  
+  /**Returns all collisions.*/
+  def collisions: Seq[Collision] = for(p <- pairs; if (colliding(p))) yield collision(p)
+}
-- 
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