nparticle emition speed


#1

I have particles moving along a curve the way I like and what I am trying to do is control the speed of the particles. I am trying to have them emit normally and the particles that are further away from the emitter accelerate.

I tried creating an expression in the per particle(Array) attributes acceleration but it didn’t seem to have any effect.

nParticleShape2.acceleration+=.5 is what I used I don’t use expressions very often so I might have done something wrong despite maya accepting the expression input.


#2

The acceleration is vector added to the current particle velocity, so for example if you said:
acceleration =<<10,0,0>>

The particles would then have an acceleration (like gravity) acting along the x direction.
If they don’t have much drag they will natural go faster and faster over time with a constant acceleration.
You could also add to the current value each frame by using “+=” above, but I don’t think that is what you are after.

If instead you want the existing velocity of the particles to pick up over time you could scale the particle velocity, for example:
velocity *= 1.1
However the particles will go shooting off after a while if you do that.

You might like to make your curve a field: select it and the particle system then do fields: volume curve. Perhaps you want to use the awayFromAxis on this field to repel locally from the curve.