Particle editor questions Created 8 years ago2016-02-07 12:14:45 UTC by Striker

It's easy to create particle systems that are constrained by a box or by a sphere( there are some initializers built for that), but I'm having a bit of a problem trying to constrain the point of origin to a spherical plane.Essentially I want to create sort of a vortex, but particles also fall down from that plane, twisting around the axis a bit. How can I constrain the point of origin to a random position on a spherical plane?
Also, how do you actually implement a life decay? I think it's an "operator" or something, but whateverr values I put in it, it acts in retarded ways, either spawning all the particles and then stopping or fading a few seconds after.

As an advanced question, does anybody have experience with "control points"? Say I want the particles to flow around an object, I'd need control points right?

Oooh this seems like a fun one to tackle!
To answer your question about control points: yes and no.
You can give a system a "rotate around axis" operator. But if you want them to move inward towards a centralized point, then you need a control point and you need to give a "pull to control point" force.

I've outlined the basics below, and from here you just tweak the values to get things looking right.Renderer
Render Animated Sprites (leave at default)

Operator
Movement Basic (allows the particles to actually move)
Movement Rotate Particle Around Axis (self explanatory)

• rotation axis: 0 0 1
• rotation rate: 180

Alpha Fade and Decay (fades the particles out based on % of lifetime)

• start alpha: 1
• end alpha: 0
• Start fade in time: 0
• End fade in time: 0 (this means they instantly start at full opaque)
• start fade out time: 0.75 (given a lifetime of 1, so 75%)
• end fade out time: 1

Initializer
Position within a sphere random

• distance max: 90
• distance min: 0
• Distance bias : 1 1 0 (sets so there's no deviation on Z axis, AKA, spawns within a circle)

Lifetime Random

• Lifetime max : 3
• lifetime min: 1

Emitter
emit_continuously

• Emission rate: 100 (particles per second)

Force Generator
Pull towards control point (you'll have access to control point location now)

• amount of force: 10000
• control point number: 1

Also don't forget you need to make a particles manifest for you map before you can use them!

Thanks for your swift response. It works:But now I have another dilemma:
The "thing" that emits these particles in my map has a radius of about 1200 units. Needless to say, if I put that radius in the initializer, the sprites will be pretty sparse. What parameter do I have to modify to increase the size of the sprites? Seems like the max number of particles is 5000, but even with that on a radius of 1200 units it's still sparse( plus, not good for the framerate probably).

If you're not dynamically changing the particle size, the size is specified in the general settings.

A work around could be setting the particle system to emit within the 3D skybox.
Set the particles 16 times smaller and then duplicate the system in place 2 or 3 times. Since each particle is rendered and calculated separately, it should work well.