random control

[scene]

using the rand function to create expresions will give a huge help .
for example , in case of spirte
in spriteTwistPP ATTR you should write a creation expresion
particleShape1.spriteTwistPP=rand(360);

and define a new perparticle ATTR , called , say .. randTwist
and write a creation expresion for it
particleShape1.randTwist=rand(-.8,.8);

now go backe to the spriteTwistPP and write a runtime expresion
particleShape1.spriteTwistPP += particleShape1.randTwist;


and you will get a random twist for each particle

[modernPrimitive]

Thanks Scene,

I'm using a geom instancer but I guess the principle is the same. I am currently doing this with the following line for the particle creation:

particleShape1.ppCustRotationVector += <<0,rand(-0.001,0.001),0>>;

-I need to keep the rotation on a certain axis, thus the slight variance on only the y axis.

I think I might get something happening using a sort of mod operator with time to change the direction of the rotation when it reaches an apex. My math isn't good enough to anythin other than linear type calcultations. (wish I'd paid attention at school!)

-thanks for the help though - the main challenge is getting the "wafting" from one apex" to another" type motion.

[scene]

I think I might get something happening using a sort of mod operator with time to change the direction of the rotation when it reaches an apex. My math isn't good enough to anythin other than linear type calcultations. (wish I'd paid attention at school!)

-thanks for the help though - the main challenge is getting the "wafting" from one apex" to another" type motion.

maybe using a locator will help , put this locator where the apex is ( where you want to change the direction of the rotation)
example
and using a (if) function , so you will telling maya , when the particleShape.position = the position of this locator ( wich defined in a vectoer variable) , then change the direction of the rotation.

[Vympel]

You can use the cycle options of Instancer more expressions to randomize the values,trying to use some animated leaves and create a per particle attribute to control de age option of instancer node, more expressions to randomize the position, scale and acceleration, you can place these expressions in "custom attribrutes" and or in the standard per particles attributes.

You tried the 'if statement" to control the rules of rotation?

[modernPrimitive]

You can use the cycle options of Instancer more expressions to randomize the values,trying to use some animated leaves and create a per particle attribute to control de age option of instancer node, more expressions to randomize the position, scale and acceleration, you can place these expressions in "custom attribrutes" and or in the standard per particles attributes.

You tried the 'if statement" to control the rules of rotation?

Yeah, I kind of did a (if particleID+time > a certain value then rotate in a different direction.)

I can't seem to get the cycle options of the instancer to work the way I would like it too (never used it before). I'm under the impression that it merely cycles through a list of geometry per frame (or per second) per particle. I was hoping you could get it to work as a sort of geometry Birth list which would cycle through the geometry at birth time and then keep trhat geometry for the duration of the particle's life. - couldn;t get that to work though?

[Vympel]

The cycle really cycle among a list of geometrys (but the particles keep the geometry for all of your life). You can make expression to the cycle emit a determined geometrys for a period of time or using expressions to randomize the geometrys emmitted in this periof for example

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