Fixed throwing problems with 2+ pointers

lib/interaction.js

@@ -122,12 +122,23 @@ export class PointMap extends MapProxy {
 }
 
 export class InteractionDelta {
-    constructor(x, y, zoom, rotate, about) {
+    /**
+     *Creates an instance of InteractionDelta.
+     * @param {*} x
+     * @param {*} y
+     * @param {*} zoom
+     * @param {*} rotate
+     * @param {*} about
+     * @param {*} number - number of involved pointer
+     * @memberof InteractionDelta
+     */
+    constructor(x, y, zoom, rotate, about, number) {
         this.x = x
         this.y = y
         this.zoom = zoom
         this.rotate = rotate
         this.about = about
+        this.number = number
     }
 
     toString() {
@@ -217,14 +228,14 @@ export class InteractionPoints {
             let currentAngle = Points.angle(c1, c2)
             let previousAngle = Points.angle(p1, p2)
             let alpha = this.diffAngle(currentAngle, previousAngle)
-            return new InteractionDelta(delta.x, delta.y, zoom, alpha, cm)
+            return new InteractionDelta(delta.x, delta.y, zoom, alpha, cm, csize)
         } else if (csize == 1 && psize == 1 && this.current.firstKey() == this.previous.firstKey()) {
             // We need to ensure that the keys are the same, since single points with different keys
             // can jump
             let current = this.current.first()
             let previous = this.previous.first()
             let delta = Points.subtract(current, previous)
-            return new InteractionDelta(delta.x, delta.y, 1.0, 0.0, current)
+            return new InteractionDelta(delta.x, delta.y, 1.0, 0.0, current, csize)
         }
         return null
     }

lib/scatter.js

@@ -127,7 +127,9 @@ class Throwable {
         this.lastframe = t
         if (dt > 0) {
             // Avoid division by zero errors later on
-            let velocity = { t: t, dt: dt, dx: delta.x, dy: delta.y }
+            // and consider the number of involved pointers sind addVelocity will be called by the
+            // onMove events
+            let velocity = { t: t, dt: dt, dx: delta.x / delta.number, dy: delta.y / delta.number}
             this.velocities.push(velocity)
             while (this.velocities.length > buffer) {
                 this.velocities.shift()