How To Replace Particles With Geometric Objects?

[rezeerf]

Hello all together,
how can i replace particles with some geometric objects ? I want to make a scene of a "Saturn Ring" with a camera flight over. Like the scene in the intro of startrek-voyager. So i made a nurbs-cycle and than set emitt from object ! After a few tries the particle-ring was verry nice. But now the question is, how to make "Rocks" from this particles wich are randomised in its volume in a specific range of values e.g. "No rock should be bigger than 0.5 and no rock should be smaller than 0.1"
Can every one help me ?

Greets
Jan

[gmask]

$scale = .1 + rand(.4);

[rezeerf]

Please can you tell it a little more detailed ?

[gmask]

are you at all familiar with particle instancer?

[rezeerf]

I made my first steps with it today, because i does not need this before. Now i know how to replace the particles with some rocks (from Poser) wich i have .fbx exported by DAZ-Studio. But where i have to place the formula which you have written ?
Greets from Germany
Jan

[rezeerf]

And another question, how can i freeze the result. In a scene where the particles do not move anymore. Because it should be a ring of rocks. Not an explosion.

Greets from Germany
Jan

[tmagill]

Your first question "How do I create a random size expression"?
1) open the particleShape Attribute Editor
2) go to Add Dynamic Attributes > click on General
3) a new window will pop up, give the Attribute a name, such as randSize
- date type: Vector
- attr. type: Per Particle Array
4) click OK
5) Now you will find this new attribute called 'randSize' in the section Per Particle (Array) Attributes
6) right-click randSize and choose 'Creation Expression'
7) in the Expression Editor type the following (note that I use particleShape1, YOUR particle might have a different name so you got to put your own particle name into the formula:

float $range = rand(.1,.5);
particleShape1.randSize = <>;

8) back in the particleShape Attr. Editor go to the Instancer (Geometry Replacement) section
9) In the General Options open the Scale rollout
10) choose randSize (probably at the very bottom of the list)

OK, here's how you can freeze your particles:
1) after you like the way they look go to the Dynamics menu > Solvers > Initial State > Set For Selected.
Whatever they looked like will now be set to be the new look for frame 1
2) Now set the Emitter's Rate to 0 and the Particle's Conserve also to 0
Voila!

I realise this info might be a bit late for you, since you posted your questions a few days ago, but maybe someone else will stumble upon this in the search for the same solution. Schoen' Tach noch, Tom

[joojaa]

Well i happen to have posted very exactly just this thing earlier juat add water (oops ahem instancer ):

CODE
{
$particleS=particle;
addAttr -ln ScalePP -dt vectorArray $particleS[1];
addAttr -ln ScalePP0 -dt vectorArray $particleS[1];
addAttr -ln RotationPP -dt vectorArray $particleS[1];
addAttr -ln RotationPP0 -dt vectorArray $particleS[1];
addAttr -ln IndexPP -dt doubleArray $particleS[1];
addAttr -ln IndexPP0 -dt doubleArray $particleS[1];
for ($i=0;$i<1000;$i++){ // 1000 asteroids
   $rot=rand(360);
   $rad=100+rand(10);//10=width 100 inner radius
   emit -object $particleS[0]
        -pos ($rad*sind($rot)) (rand(10)) ($rad*cosd($rot))
        -at ScalePP -vv (rand(10)) (rand(10)) (rand(10))
        -at RotationPP -vv (rand(360)) (rand(360)) (rand(360))
        -at IndexPP -fv (floor(rand(10))); //index for instancer
}

}

from here, please read the original therad before any further questions on it, such as how to connect isntancer:

http://www.highend3d.com/boards/index.php?...amp;hl=asteroid