Processing: Creative Coding and Computational Art

To avoid unintentional clumping of the balls at collision, I borrowed a nice hack from
Keith’s example, which essentially moves the balls a little away from each other upon collision
detection so that clumping is avoided. It’s not a perfect fix, but it sure is nice and
simple.
We’re almost home now. The last steps left are to rotate the rotated ball position values
and velocities back to the original rotation at collision and to update the balls’ positions to
the screen (remember that I treated the rotation locally with regard to the vector between
the balls, rotating b[1] around b[0]). Updating the balls’ screen positions just entails
adding the final ball positions (bFinal) to b[0].
That’s it! Definitely take some time playing with this sketch, plugging in different values for
the balls’ radii (which, again, control mass) and the initial velocities, both defined in the
sketch’s main tab.
There is so much more that could be done with this sketch, and collisions in general,
including the addition of more balls. Likewise, orb-orb collisions could also be introduced
to the Asteroid Shower example. That being said, I think this chapter’s gone on long
enough.
Summary
This chapter began with a brief overview of some of the technical issues involved in computer-based
animation, including the concept of threads and the use of timeline-based
keyframe models commonly found in high-end animation applications. Comparing Java
and Processing animation code side by side, I showed how Processing’s draw() structure
encapsulates much of the low-level (and annoying) aspects of programmatic animation.
Beginning with a simple moving ball and eventually adding simple physics, you explored
easing, springing, and the concept of soft-body dynamics. Coding collisions, with some
help from code guru Keith Peters, I introduced different approaches for handling both
orthogonal and non-orthogonal 1D collisions, including ways to work with multiple surfaces
and objects. Finally, I introduced an advanced 2D collision example that included
conservation of momentum calculations.
In the next chapter, we’ll add interactivity into the mix, allowing the user to interact with
your sketches. We’ll also discuss the possibilities of generating applications and graphical
user interfaces (GUIs) in Processing.
MOTION
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