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Smooth Movement animation

Artoonix version 1.7 introduced so-called "frame-tweening", a tool that makes it exceedingly easy to create movement effects in animation. Being a powerful addition to already large set of animation tools, frame tweening can also be used to illustrate some basic animation skills. This article discusses why some animations look smooth and fluent while other don't (while seemingly they should have!). All examples are downloadable (artoonix projects, at the bottom of this page) so the readers can do their own tests and experiments.

Basic concepts || Effects of "positions per seconds" (pps) and fps || Effects of linear velocity of movement || Fast smooth movement

Basic concepts

To start off, let us introduce some terms that will be used throughout this article.

Let us work with a very simple animation of a square passing from the top-left corner of the screen to the bottom-right. It doesn't look like much animation yet, so let us have a look at the way we can improve the situation and test various parameters introduced above.

Effects of "positions per seconds" (pps) and fps

The next example shows the same animation but with 5 frames inserted using standard tweening tool in artoonix. The whole movement is done in 1 second (meaning that there is a 200 millisecond delay in change over of the frame). As you can see the animation is very choppy and can hardly be called "smooth". Let me remind you that in this case the frame rate is 30fps, and velocity is 275 pixels/sec.

Let us now increase the pps to 30. Once again, simple in artoonix - use frame tweening in the original animation and now set the frame delay to 33milliseconds (to again have the movement completed in 1 second). The result is below.

It is clearly better and rather smooth. However it is not quite perfect just yet. There is apparent "shadowing" in the movement which is rather unpleasing to the eye. Can we improve it by further increasing the pps number? Unfortunately not - the fps is set to the maximum of 30 so whatever frames we would insert would be lost during export. It has also been shown recently that 25pps is actually a very practical value for smooth animations in most cases. So what is going on here? Let us try now the next parameter - movement velocity.

Effects of linear velocity of movement

The animation below is exactly the same as the previous example but the velocity has been halved to 190 pixels/second. This clearly results in much reduced "shadowing" effect.

which can be completely removed by reducing the velocity to 100 pixels/second as shown below:

So, the question that rises whether the 100 pixels/second velocity is a magic number to guarantee smooth animation? The answer is, in general case, "no", as the actual perception of the movement depends on many factors, such as background elements, their relative movement, complexity of movement of the object itself and many others.. However it does give a good ballpark figure of ensuring smooth motion.

Fast smooth movement

From the text and examples above one could conclude that only slow animation can be smooth. It is so if only the three parameters (pps, fps and velocity) are considered. Another, very important one is the actual perception of movement that is created in human visual cortex (that's a part of the brain where actual image processing is done on the basis of the "frames" that eyes capture). For instance, consider the animation below. The effect of fast movement is pretty solid, no jerkiness or other detrimental effects are visible.

And yet the sequence is extremely simple - what it is exactly you can see for yourself in attached to this article Artoonix project that you can download at the bottom of this page (the one that is labeled "FAST" ;)).

To conclude, it is very easy to create simple yet very effective animations in Artoonix, especially when used with frame tweening. We have demonstrated here that a number of parameters needs to be considered and applied properly to achieve perception of a smooth animation.

The complete set of artoonix projects that we used in preparing this article can be downloaded here (compressed with winrar, 227kb file).
Start experimenting yourself, and, most importantly, have fun!


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