varying particle speed?

What is the way (if any) to vary particle speed - so that individual particles move at different speeds? I’ve tried all the settings, I’ve read all the docs, but I can’t get it. The ‘random velocity’ value changes the direction of the emitted particles, but I just want varying speed (like rain). Help please, I need this info today…

You can animate the speed of the particles over time, however, it seems (yet another bug in the Blender particles system) that when you slow down time, it only slows the velocity and does not take the life of the particle into account.


ras_particle_speed_change.blend (412 KB)

Nay, this works as it is supposed to. E_Speed is a factor for the emission speed of the particles. Here 100 Frames scale to Sta-End.

But I think this is exactly was pawel was looking for anyway.

Also, if you enable “Mass from size” from the extras tab and give some “Rand” value that is above the button, “Drag” value at Global effects will affect differently on different sized particles.

Another way would be to use a texture as a factor for initial particle speed.

Map to Panel:

  • PAttr
  • IVel
  • DVar = 0

Use a cloud texture for random variation of the starting speed.

Thanks for the suggestions.

SoylentGreen’s suggestion’s working exactly as it should. Thanks :slight_smile:

hhoffren’s method seems fine, but you don’t always want to have particles of different sizes (though, as a matter of fact my particles ARE :slight_smile:

The E_Speed vaule doesn’t seem to be doing anything. And even if it did, I suppose it would vary the speed of ALL particles, wouldn’t it? And what I want is steady speed, but different for each particle.
The reason it’s not working might be (I think) the fact that I’m using bake, because otherwise the particles don’t work - it happens when the emission doesn’t start at frame 1. I believe it’s a bug, although I’ve read you have to rewind to frame 1 and start playing from there for it to work, which I still think is a buggy feature)

Well, it seems it IS working, but in a very strange way. When I use a curve which should make them accelarate, only the starting value of the curve is used, and the particles continue to move at that speed.
That’s not really my concern now, but I was wondering. These features aren’t documented and it’s hard to say how they work precisely.

But for me, SoylentGreen’s solution is all I need :slight_smile:

Thanks to all

Nice that I could help out here. :slight_smile:

E_Speed is only the emitting speed of the particles (to be exact: it is a scale factor for the emitting speed). You can’t control the speed of the particles directly. Particles are moved by forces, try to achieve a goal or a certain point.

So there are lot’s of ways to change the way particles move. You have many ways to accelerate them or damp their motion, and if you do that in a clever way, you can control the speed of the particles to a high degree.