Is there any way to make particles to follow the shape of an object or a track? If so, is there also a setting to set how rough or precisely it follows the object or track?
Also, is it possible to make particle halo sizes grow or shrink as the move farther from the emitters surface?
you can use a lattice to make particles follow a path…
ask fligh%
Add a curve to your scene. Make the curve the parent of your particle emitter. (normal parent). Then select the curve and go to its Feilds and Deflections tab in the Physics buttons. Under field type select Curve Guide.
Now the particles will follow the curve. You can use max dist to control how many of the particles follow the curve. And you can use more than one curve guide.
Yes, you can put the emitter inside a Lattice and aim the particle stream along the length of it. Even better is a Curve Guide (F7 twice, in the Fields menu) where you can set the Min and Max distances and the FallOff (you can even stick an IPO on the Fall to animate it).
In the Material context menu of the IPO window leftclick on HaSize and then Ctrl-Leftclick an IPO at zero on the grid and again for max size on the Y-Axis (you can tweak the positions in edit mode).
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I beat you
Snap!
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why don’t you look at the particle hair features in the docs?
http://mediawiki.blender.org/index.php/Manual/PartXIII/Particle_Hair
[and you can insert keyframes to set the size of a particle… but it’s based on time since emitted, not distance from where it was emitted]