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unstable
11-22-2014, 07:34 AM
I was just messing around trying to use particals for drops of liquid moving on a flat surface. I can make them stick to the surface while they move, but was wanting to add trails. Think of rain on a car window. Is this possible?

ernpchan
11-22-2014, 07:37 AM
You could attach another emitter as a child and have it emit particles to leave a trail.

jeric_synergy
11-22-2014, 11:28 AM
Is another emitter required? Can't the first just emit particles itself?

ernpchan
11-22-2014, 02:29 PM
I don't know of a way to get particles to create particles based on where they are/were without a child emitter. If there is a way I'm all ears.

prometheus
11-22-2014, 02:34 PM
nope...you always have to have a secondary emitter type, either you let a particle emitter collide with an object that by itelf has an emitter attached to itself, or you add a secondary particle emitter and parent to the first, and set the secondary emitter to spawn by using the first emitter, by setting nozzle mode to parent emitter or end.

You could use points or splines, and given the right birth rate mode and ratio, the birth of particles will start from the starting point of the spline, and then continue to "grow" along the spline.

Michael

jeric_synergy
11-22-2014, 08:45 PM
:stumped: I usually think of an emitter as a sparkler, shooting out particles. If the emitter is in motion, and stuck to a surface, and the particles are sticking to the surface (as the OP stated), I would think an "inverse-age-to-size" gradient would result in trails, esp. if the Scene were using HVs to render the particles.


Related question: is it possible to have an entire object act as a nozzle, but only when struck by a particle, & only at the point the particle intersects it?

ANOTHER related question: is it possible to have the initial vector direction of particles be the inverse of the direction of the emitter? IOW, any direction the emitter was moving, the particles would be moving in the opposite direction?

ernpchan
11-22-2014, 11:11 PM
You would set the object to be a collision object set to erase and have the child emitter set to emit based on parent death. The fire particles from the parent at the collision object.

For the inverse vector you could try parenting a null to your emitter that's placed behind it and use that as a target for the emitter. Then animate your emitter with align to path. That might work.

prometheus
11-22-2014, 11:24 PM
:stumped: I usually think of an emitter as a sparkler, shooting out particles. If the emitter is in motion, and stuck to a surface, and the particles are sticking to the surface (as the OP stated), I would think an "inverse-age-to-size" gradient would result in trails, esp. if the Scene were using HVs to render the particles.


Related question: is it possible to have an entire object act as a nozzle, but only when struck by a particle, & only at the point the particle intersects it?

ANOTHER related question: is it possible to have the initial vector direction of particles be the inverse of the direction of the emitter? IOW, any direction the emitter was moving, the particles would be moving in the opposite direction?

Object as nozzle only upon other particle impacts, no donīt think so.
similar effect to that action is to make your object spawn particles anyway when particles impact, but for that you should add a collision object on to your object that is to spawn the particles, set the collision to erase.
the secondary emitter that is to spawn from the object should be parented to the first emitter that hits the object. so you should add a second emitter and parent that to the first...and that child emitter should have itīs nozzle set to emitter end..so when the first emitter hits your object with the collision object set to erase, the first emitter will die..and consequently give birth to the child emitter which is set to parent emitter end.
for explosion like impact, add some vibration in the child emitter.

as for opposite direction, sure ...but only for straight moving emitter, turn of particle motion and revers particle velocity direction, but why do you want that...canīt see any use for it.

Edit...I am writing to long descriptions..ernpchan beat me to it.