Question

I want to animate MoviveClips/Sprite objects as smootly as possible. However so far the only method that works is placing the movement code into the EnterFrame event handler. There is one problem with this approach: when the framerate on a specific machine is below the desired framerate then the whole game slows down. I want to be able to do this in a time-independent manner.

Answer 1

There are two ways to do programmatic animation within the Flash player. The first you already pointed out by using a onEnterFrame. However, as you might already have noticed, to get a smooth animation you need to increase the overall frame rate of your movie. Doing this will also increase the CPU load for the entire period of time your SWF runs. This is not something you always want.

The other way of doing programmatic animation is by using a timer. Within a timer handler it is possible to call a function named updateAfterEvent which will update the screen independent from the FPS you’d set for your SWF. Therefore, using a timer leaves a gateway to do smooth animation within the Flash player without increasing the overall frame rate of your SWF.

Two years ago or so I set out to create my own tween libraries for Flash (because of my frustrations with the then existing tween libraries available). I released it under the name Coretween and this library lets you, among other things, choose what type of animation you prefer for every individual tween. On the documentation page I give an example of the difference between frame based and time based animation. The example SWF on that page runs at 12 fps but as you can see, the lower circle tweens much smoother because it’s controlled by a timer that ticks at 60 fps and updates the screen in-depended from the SWF frame rate. Do keep in mind though that even the timer ticks at 60 fps in reality the Flash Player will never be able to achieve this frame rate. However, it will try to achieve this frame rate which results in a much smoother overall animation.

Unfortunately until now I’ve not been able to release a 1.0 version of my library but as far as I know it’s pretty stable. You’re more than welcome to use it in any way you see fit. I’ve used Coretween in many commercial productions including this one we did for StGeorge bank here in Australia.