Part Four - Modifiers

So now, that was about all there was to setting up the emitters and lights. What's left now are the modifiers. You use them to attract, repel or destroy particles. Also you have modifiers to simulate wind, friction and turbulence. And, of course, you have the deflector (self-explanatory). I will tell you a little bit about how I used them in this scene. Usually, you don't set up the emitters and then the modifiers separately. Those settings go hand in hand. If you want a particle stream to be bent by 30 degrees on a circular path, you would use an attractor (like a satellite's path being bent by planets). Now all that counts to determine which path the particles will take is the speed/attractor ratio (leaving the path that the particle stream takes through the attractor field constant). This means that you get the same results if you raise the speed of the particles AND the strength of the attractor the same time. Some knowledge in basic physics is helpful here. If you don't have that, well then just play around with the settings and watch what happens. But remember to change one thing at a time :-)

Once you start with your own scenes, you will find it useful to divide the modifiers into global and local ones. In my scene I have two global modifiers (left screenshot - sorry about the German names). One that simulates gravity and one that destroys those particles that have left the field of view (no need to waste capacities). Those (at least the gravity) apply to the whole scene (that's why they are called global, duh). That was easy. Trickier are the local ones (right screenshot). They affect a certain area (here around the saw of course). Sometimes they move (wind coming from some desktop vent) or remain at one place but only affect a certain area (wind from a ceiling vent). What I needed most in this scene were some particles that are being thrown up (by the rotation of the saw). Of course, I used several attractors to achieve that. Then, I needed to get rid of many stray sparks, which I did with destroyers. And last but not least, to add some life, I used some turbulence modifier. I will not list all settings here. Just pick apart the scene and look for yourself. This again is one of the things that totally depends on what your scene looks like and what you are trying to achieve. For example my global gravity modifier (lower left screenshot): though it works fine in my scene it might do just about nothing in yours. If your particles have a greater speed or even if your scene is built on a larger scale, you would need a higher gravity value to achieve the same (relatively seen) diversion.

There is one major limitation (XL 5.x) to modifiers, though. You can not make a modifier to affect only a certain emitter. Every particle that flys through the modifiers range of power will be affected. This is a major drawback since you can not seperate the particles by modifiers (f.e. the smoke would be more affected by wind than the sparks). So remember this when you set up your scene.