Timebased Animation Idea (FRIM & QuickBox2D)

import com.actionsnippet.qbox.*;

// change the frame rate and test...
stage.frameRate = 60;

[SWF(width = 800, height=600)]

var sim:QuickBox2D = new QuickBox2D(this);


var circle:Shape = Shape(addChild(new Shape()));
with(circle.graphics) beginFill(0), drawCircle(0,0,50);
circle.x = 100, circle.y = 100;


sim.start();

var startTime:Number;
// delay the start a bit
setTimeout(function():void {
  startTime = getTimer();
  sim.addEventListener(QuickBox2D.STEP, onTimeStep);
}, 500);

function onTimeStep(evt:Event):void{
	
	circle.x += (600 - circle.x) / 12;
	
	if ((600 - circle.x) < 1.5){
		trace("frameRate: ", stage.frameRate);
		trace("totalTime: ", getTimer() - startTime +" ms");
		trace("totalTimeSteps: ", sim.totalTimeSteps);
		sim.removeEventListener(QuickBox2D.STEP, onTimeStep);
	}
}

Note: This snippet requires QuickBox2D 1.0 or greater

Really not sure how I didn’t think of doing this before last night… I realized that the simple FRIM code inside of QuickBox2D can be used to make any standard frame-based style ActionScript animation time-based. In this snippet I do a simple ease out one liner:

circle.x += (600 – circle.x) / 12;

Code like that on an enterFrame would run at different speeds depending on your framerate. However, if you run it on QuickBox2D’s STEP event it runs independent of fram-erate. I’m obviously going to just wrap this up into it’s own mini-library separate from QuickBox2D and do a more in depth post about it… but for now, this snippet just traces out the results. These are my results from my macbook pro dual 2.4 intel….

frameRate: 12
totalTime: 1165 ms
totalTimeSteps: 93

frameRate: 24
totalTime: 1162 ms
totalTimeSteps: 93

frameRate: 30
totalTime: 1166 ms
totalTimeSteps: 91

frameRate: 60
totalTime: 1167 ms
totalTimeSteps: 93

frameRate: 120
totalTime: 1168 ms
totalTimeSteps: 91

Anyway… will peel the FRIM code out of QuickBox2D and wrap it up in its own library sometime soon…