how to fade splash/mist particles before edge of sim box

[ttdww]

Doing a splash sim.. again. Trying to figure out how to fade out splash/mist particles based on their age (either using opacity, or by their size) and how can I do it as world mappable? The problem is I need to fade them off as they approach the edge of my sim box so they don't vanish. I see the PA button and multipler however I'm not fully understanding how to control if after reading the manual.

Also would like to know if it's possible to have splash/mist go outside of sim box - that would be another solution.

Thanks!

[ttdww]

I found that the param that controls the life outside of grid was 0 so they were being killed instantly, so issue averted. However, for the future, would still be interested in tips on controlling shader/opacity over life. Thx!

[Gosho.Genchev]

Hey there,

You could animate the Size Multiplier such that the particles start shrinking once they reach a certain Age.
The PA (Particle Age) button changes the way the animation is evaluated. When enabled, each particle looks up the animation on the timeline starting at frame 0, regardless of what frame it was born on. Essentially, it is as if each particle carries a copy of the animation and starts using it the moment it is born.
So, if your Size Multiplier with PA enabled goes from 1 to 0 over 30 frames, particles will start shrinking the moment they are born, and shrink to 0 over 30 frames. Every time a new particle is born, this process will repeat.
Alternatively, if Size Multiplier with PA disabled goes from 1 to 0 over 30 frames, when rendering your simulation, all particles will simultaneously be shrinking over the first 30 frames of the rendered simulation, and after this, your render will be empty.

One treats the animation as 'global' and ignores *when* the particle was born. The other forces each particle to go through the animation.

If you want particles to start shrinking after they've lived for 50 frames, you can:
1. Enable PA on the Particle Shader
2. Animate the Size Multiplier such that it is 1 from frames 0 to 50, and it starts going down after this.
3. Make sure that the Age particle channel export is enabled (from the Output roll-out of the simulator) for the particle group you are simulating/rendering


We'll also update the docs right away - I didn't realize this info is missing.

Cheers!

[ttdww]

Thanks for those ideas! Much appreciated. Sorry this reply took forever.