View Full Version : Particle emitter based onanim surface height

11 November 2002, 07:20 PM
If I have a surface with high points and low points and those points are animated so the high points are constantly changing. How do I get the particles to emit only from the high points from the surface for that given frame?
First I tried using a simple gradient based on Y distance to object for the birth rate. That bonked.
Then I tried what the manual suggested by getting them to emit from a collision object.
What I did for this was have my animated surface act as a surface emitter for the nozzle. Then under Generated by I set it to collison event. I then finished setting up the particles for the emitter as normal. Next I added a collision object which I set the type up as a plane. Then set the mode to event, although I think I want to set it to erase. I then changed the radius/level so that it would be at the height that I want the particles to begin from the surface. Then I generated the particles with the FXstart button just to be on the safe side. That did not work. I tried parenting the collision plane to the surface and then changing the emitters nozzle to parent-collision and that also did not work .
Any clues to what I'm doing wrong?

11 November 2002, 07:40 PM
Need to set the collision object plane to erase and position it just below the surface so that only above will produce particules.
The only way a gradient will work is that if your emitter object has differant colors that match where you want the particules to emit from,using that it would work planer gradient.

11 November 2002, 07:53 PM
you could make a white to black gradient in photoshop then map it to the Z axis - the trick is to turn on world coordinates so its stuck to the world, then only the high points will emit particles. i used it on a proj lately & it works great.

11 November 2002, 11:19 PM
Thanks for the replies. I finally gave up and went outside to play in the snow with my Huskey. After through a few snowballs for him I realized that I was looking at the problem backwards. I changed the surface to the collision surface and the plan to the emitter. Now she works just the way I wanted.
Thanks again.

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