Emit strands from instanced geometry

[Pancho]

I'm struggling here a bit to find the right approach. For a small project I want to create dandelions in the state when they spawn the seeds with the fine hair (yes, the little umbrellas/parachutes).

To emit the seed from the seedhead and distribute them is no problem. My problem is divided into two areas.

First: How do I emit the particles/strands on each seed? Currently each seed is an instance of the base geometry. In order to emit strands I would need to access the geometry and the cluster (or weight map) which defines the area for emitting. Also there needs to be a value which defines the angle. The more seeds are in a location, the more the hairs need to point away from the seed. In locations with lesser density, the hairs need to be more in the form of a disc (in one plane).

Second: Is there a way to check collisions with instances? When the seeds fly away I want to eliminate self collision of the seeds and collision with other plants and the seedhead. As each seed is made of about 500 polygons, with about 200 instances on each dandelion, that's about 1.000.000 polygons for each plant. So having actual geometry is a bit of a pain.

As I'm new to simulation I'm not quite sure two solve both problems.

Thanks in advance for any tips and tricks
Pancho

[nixx]

I don't think you can access such properties in instances. If you want to avoid actual geometry, maybe you could use strands (with intance shapes) for the actual seeds, too, as well as for the fine hair on top of them. You won't have very accurate control as to where the fine hair will grow, at least not through weightmaps or anything like that, but these grow at the tip of the seed anyway, don't they ?

(as in this: )

[owei]

....you could use a low res proxy for the emitter geo and maybe also for the collision detection of the seeds...should work to build a rough shell for one seed and let them fly..after caching all the data you need (emission, simulation with collisions and so on) you can adapt the instances to the cloud again...

cheers,
oli

[Pancho]

Thanks guys!

I already started on my own to test what could work. Currently I managed to build up everything for a still. I realized that the actual geometry which is needed for emitting strands is quite a low poly one. So far I play around with only 1 dandelion. So I used clone topology to create an object with only the fiber emitting areas. I use the copy index as a reference to the particle which is responsible for the seed. This way I can alter the direction of the hair in relation to its seed.

Next thing I want to try is animate the emitter topology. Hope this works. The dandelion seeds already move. Afterwards I want to test the self collision if the seeds get spawned and the movement of the stem.

Cheers
Thomas

[owei]

...sounds good! Show something if you have ;)

cheers,
oli

[Pancho]

So, for a start it is quite o.k. Now I need to do the stem animation. Hopefully I manage to deform geometry (instances?) via strands and don't run in cycle problems as the flower heads need to be attached to the stems.

Moderator edit: fixed embedding - HB

Thanks!

[owei]

..Wow! That looks awesome..!!Keep it up!