particle collision radius over time

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  10 October 2012
particle collision radius over time

Hey guys, I have a pretty simple concept I need to execute but I feel as though the solution is a bit tougher than I initially thought.

I have a ball bouncing across a polyPlane and upon each collision the ball emits particles. Here's the line of code I've got running the sim:

if (rigidBody1.contactCount > 0) { string $cp[] = `rigidBody -q -cp rigidBody1`;

int $i;

for ($i = 0;$i < size($cp);$i++) {

eval ("emit -object particle1 -pos " + $cp[$i]);



Upon each collision I need the particles to grow over time, enhancing the effect of dust rising after being displaced. It's easy on the first collision, that's just a matter of keying frames. But when it comes to the particles increasing their radius over time upon each separate collision, I'm drawing a blank.

Anyone know how I can connect the above line of code to the radius of the emitted particles?

Thanks in advance!

  10 October 2012
Well what you really want to do is to have an expression for the Per Particle Array Attributes that increases the size of the particle over time starting with it's birth.

So if the attribute you are anmating is radiius then you need to add the radiusPP attribute and then add this expression to it's runtime before dynamics


when the particle is born this will increment it's size by .1 at each frame.

you can also do this using a ramp
blah blah blah
  10 October 2012
Worked like a charm!!

Thanks man, much appreciated

  10 October 2012
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