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# 37 02-02-2004 , 07:43 PM
Registered User
Join Date: Nov 2002
Location: Pakistan
Posts: 57
A noise function is used to control the Y position of a string of particles. Arithmetic operators are used to control the amplitude, frequency and offset of the function.




1. Create an emitter with as desired parameters......

2. Create Custom Attributes as follows

a. tornodoRadius
b. tornodoTwist
c. tornodoRadiusMult


now let code:

creation Expression

particleShape1.tornadoRadius=rand (.75,1.25);

particleShape1.toranadoTwist=rand (1,3);

particleShape1.position=<<1000,0,0>>;

****

Runtime Expression

vector $pos=particleShape1.position;

float $radius=particleShape1.tornadoRadius*particleShape 1.tornadoRadiusMult;
float $speed=time*particleShape1.toranadoTwist;
float $noise=noise((time*.3)+(particleShape1.particleId* .01));


particleShape1.position=<<($radius*(sin($speed+par ticleShape1.particleId)))+$noise
,$pos.y+.1,


($radius*(cos($speed+particleShape1.particleId)))+ $noise>>;

****

and third create a ramp on tornodoRadiusMult custom attribute this ramp will be used to control its hollowness from top or bottom.....

adding source file.........check it out...!

enjoying.......!


user added image

Attached Files
File Type: rar tornodo.rar (5.3 KB, 1522 views)

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