PDA

View Full Version : mimicking lift with nparticles


stooch
01-15-2012, 08:48 PM
this is a question for duncan I guess. I want to emit a bunch of particles that behave like feathers or confetti. However I really like how ncloth based solves behave with lift. etc.

Obviously particles with instances on them wont have the same kind of calculations since they are just single vectors. So would faking lift be just a matter of adding a "lift" vector to the particle velocity based on the orientation of the instance surface normal?

thanks.

Duncan
01-16-2012, 08:22 PM
You could look at the velocity tangent to the instance normal then add a push based on that velocity. The particular formula used in nCloth comes from lift/drag formulas for airplanes, so you could look that up... it is nonlinear in the relation of speed to lift. More critical than lift, however is drag. The normal particle drag is uniform in all directions, which is not good for flat objects. You could perhaps make drag zero on the particles then damp out the velocity of the particles along the normal vector.

If you want behaviors like spinning paper strips( which the lift doesn't handle), you could perhaps also add a slight rotational torque based on the velocity.

stooch
01-17-2012, 03:29 AM
thank you sir! didnt think of damping the velocity based on normal vector. that actually makes more sense.

thanks for the hints.

CGTalk Moderation
01-17-2012, 03:29 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.