Particle 'rotation'

[j0k3r]

Hi,

i have created a particle emitter, and then i used it to create an instancer with a leaf shape.

I have to simulate the wind transporting them for a while, and i need the leaves to rotate on all 3 axes.

A particle, being a point entity, does not have a normal, or rotation capabilities, am i right ???

So how can i get them to rotate on the 3 axes ??

Thanks in advice

[mantrid]

Rather than write out an essay on this less-than-simple subject, I would suggest you do a search on this forum for "particle rotation"....as you can imagine, its been talked about extensively on here in the past.

Briefly, I would suggest you ditch the instancer and use a particle-replacement script instead. This will simply attatch a duplicate of geometry to the worldcoords of each particle at birth, as opposed to generating a particle type which resembles a target geometry...otherwise known as instancing. There are quite a few scripts on this forum that will do all that and much more for....so, when you have that working, you can therefore add any expressions and rules and animation to the duplicated leaves as you like, entirely seperate from the translational animation that is animated via the particles.

[tbriggs]

It takes about 60 seconds to set up. See the post from the last couple days 'how to control the orientation of the instancer' I agree that the maya instancer is lame. There is no motion blur on the instanced objects, there is no memory advantage, etc. A better approach is to use the particles to create motion curves and dupe and attach geometry to those curves. There are scripts around for that.

[j0k3r]

Hi,

i used a sample that you posted many posts ago....
Now the last thing: i need the particles stop rotating when they collide with the ground.

So i added a float PP attribute (statusParticlePP - representing a kind of collision flag for each particle...) and a collision event: when this occurs a script sets the value of statusParticlePP to 1.0; in the runtime script of the particleShape i keep on rotating particles til statusParticlePP == 0, else i set

instRotPP = <> // this is the aiming of a particle on the ground.

The problem is that in the mel script called when event occurs, i get a 'locked attribute' error while attempt to set statusParticlePP to 1.0.

How can i solve this ?? It's my last problem !!!!

[tbriggs]

There must be something wrong with that attribute, are you sure it is an array attrbute?. Another way would be a conditional, something like this:

if(event == 0)
{
///your code to update rotation
}

As soon as there is an event the rotation update stops.

[j0k3r]

I suppose you mean to write that code in the script executed when the event occurs...

If so, suppose a event occurs on the kth frame, which between runtime script and event script is executed first ??

Is there the danger the second one overwrites the values the first sets ??

[tbriggs]

I haven't tested that code, but no, put it in the runtime rule. I'm pretty sure event is just like any other attribute that can be queried. It counts the number of collisions.