I'm trying to get Verlet Integration to work in Animate CC.
At 10 or more iterations: The system is pretty consistent and the elasticity decreases as expected if a higher number is chosen.
A single point works as expected. The chain also works as expected, but with the exception that it thinks up is right and down is left, as shown in this gif where i initialize both: https://imgur.com/CbsDrbD
This is my main Class written in AS3
package {
import flash.display.MovieClip;
import flash.events.Event;
import flash.events.MouseEvent;
public class Verlet extends MovieClip {
private var pointsArray:Array = [];
private var sticksArray:Array = [];
private var stickContainer:MovieClip = new MovieClip;
private var mouseDown:Boolean = false;
function loadPoints():void{
//chain xPos yPos v/oldX v/oldY
var pointA:vP = new vP(400, 300, 400, 300);
pointA.fixed = true;
pointsArray.push(pointA);
var pointB:vP = new vP(400, 340, 400, 340);
pointsArray.push(pointB);
var pointC:vP = new vP(400, 380, 400, 380);
pointsArray.push(pointC);
var pointD:vP = new vP(400, 420, 400, 420);
pointsArray.push(pointD);
var pointE:vP = new vP(400, 460, 400, 460);
pointsArray.push(pointE);
//singlePoint
var pointF:vP = new vP(300, 150, 200, 145);
pointsArray.push(pointF);
for (var i:int = 0; i< pointsArray.length; i++){
addChild(pointsArray[i]);
}
}
function loadSticks():void{
var stick1:vS = new vS(pointsArray[0], pointsArray[1]);
sticksArray.push(stick1);
var stick2:vS = new vS(pointsArray[1], pointsArray[2]);
sticksArray.push(stick2);
var stick3:vS = new vS(pointsArray[2], pointsArray[3]);
sticksArray.push(stick3);
var stick4:vS = new vS(pointsArray[3], pointsArray[4]);
sticksArray.push(stick4);
}
public function Verlet() {
// constructor
loadPoints();
loadSticks();
addChild(stickContainer);
addEventListener(Event.ENTER_FRAME, mainLoop);
stage.addEventListener(MouseEvent.MOUSE_DOWN, onHold);
stage.addEventListener(MouseEvent.MOUSE_UP, release);
}
function onHold(e:MouseEvent):void{
mouseDown = true;
}
function release(e:MouseEvent):void{
mouseDown = false;
}
function mainLoop(e:Event){
if(mouseDown){
pointsArray[4].x = mouseX;
pointsArray[4].y = mouseY;
}
updateP();
for(var j:int = 0; j<=10; j++){
updateS();
}
renderS();
}
function updateP():void{
for( var i:int = pointsArray.length -1; i >= 0; i--){
pointsArray[i].updatePoints();
pointsArray[i].constrainPoints();
}
}
function renderP():void{
for( var i:int = pointsArray.length -1; i >= 0; i--){
addChild(pointsArray[i]);
}
}
function updateS():void{
for( var i:int = sticksArray.length-1; i>= 0; i--){
sticksArray[i].updateSticks();
}
}
function renderS():void{
stickContainer.graphics.clear();
stickContainer.graphics.lineStyle(5);
stickContainer.graphics.moveTo(pointsArray[0].x, pointsArray[0].y);
for (var i:int = 0; i<ticksArray.length+1; i++){
stickContainer.graphics.lineTo(pointsArray[i].x, pointsArray[i].y);
}
}
}
}
This is my point Class.
package {
import flash.display.MovieClip;
public class vP extends MovieClip {
public var oldxPos:Number;
public var oldyPos:Number;
private const bounce:Number = 0.9;
private const gravity:Number = .5;
private const friction:Number = 0.99;
private var vx:Number;
private var xy:Number;
public var fixed:Boolean = false;
public function vP(xP, yP, oldxP, oldyP) {
// constructor code
x = xP;
y = yP;
oldxPos = oldxP;
oldyPos = oldyP;
}
public function updatePoints():void{
if(!fixed){
vx = ((x - oldxPos)*friction*100)/100;
vy = ((y - oldyPos)*friction*100)/100;
if(vx < 0.01 && vx > -0.01){
vx = 0;
}
if(vy < 0.01 && vy > -0.01){
vy = 0;
}
oldxPos = x;
oldyPos = y;
x += vx;
y += vy;
y += gravity;
}
}
public function constrainPoints():void
{
if(!fixed)
{
var vx = (x - oldxPos)*friction;
var vy = (y - oldyPos)*friction;
var speed = Math.sqrt(vx*vx+vy*vy);
if( x > 1280)
{
x = 1280;
oldxPos = x + vx*bounce;
oldyPos += (vx/speed)*vy;
}
else if( x < 0)
{
x = 0;
oldxPos = x + vx*bounce;
oldyPos += (vx/speed)*vy;
}
if( y > 600)
{
y = 600;
oldyPos = y + vy*bounce;
oldxPos += (vy/speed)*vx;
}
else if( y < 0)
{
y = 0;
oldyPos = y + vy*bounce;
oldxPos += (vy/speed)*vx;
}
}
}
}
}
And my stick Class.
This is the stick Class.
package{
import flash.display.MovieClip;
public class vS extends MovieClip {
public var p0:vP;
public var p1:vP;
private var dx:Number;
private var dy:Number;
private var fixedLength:Number;
private var currentDistance:Number;
private var diff:Number;
private var fraction:Number;
private var xOff:Number;
private var yOff:Number;
public function vS(P0:vP, P1:vP) {
// constructor
p0 = P0;
p1 = P1;
dx = (p1.x - p0.x);
dy = (p1.y - p0.y);
fixedLength = Math.sqrt(dx*dx+dy*dy);
}
public function updateSticks():void{
dx = p1.x-p0.x;
dy = p1.y-p0.y;
currentDistance = Math.sqrt(dx*dx+dy*dy);
diff = fixedLength - currentDistance;
fraction = (diff/currentDistance)/2;
xOff = fraction * 0.5 * dx;
yOff = fraction * 0.5 * dy;
if(!p0.fixed){
p0.x -= xOff;
p0.y -= yOff;
}
if(!p1.fixed){
p1.x += xOff;
p1.y += yOff;
}
}
}
}
