View Full Version : particle instancer : scale helping

04 April 2012, 08:15 AM
Hi everyone, this is my first pot on this forum. So please forgive me if that's not the right place for my question.
I have a particle system with an instanced mesh. I want to have a special scale depending on the age : bigger over life in y axe, but smaller over life in x axe and don't change in z axe. What should i type in my customScale expression ? Thanks a lot !

04 April 2012, 03:26 AM
there are different way to do it, this is mine.
Create a vector attribute and call it myScalePP.
Create a float attribute and call it tmpRamp. You need this because you will use ageNormalized, and is not created my default in the particle shape. Assign a ramp to that.
Then write this in creation and in runtime expression

float $myX = 1 - linstep (0, 1, nParticleShape1.ageNormalized) ;
float $myY = linstep (0, 1, nParticleShape1.ageNormalized) ;
nParticleShape1.myScalePP = <<$myX, $myY, 1 >> ;

04 April 2012, 03:50 PM
Thanks a lot, I'll try this on tuesday. But I have another problem too. I have my particles instancers emitted by an omni in all directions. What I want is a lot of particles emitted in a 180 direction or better in a 200-220 direction, and few particles ramdomly emitted in the other 180 direction or 140-160 direction. You know what I mean ? How could I do that ? Thank you

04 April 2012, 04:24 AM
you can use multiple emitters connected to the same particle shape, so directional + omni or whatever you need

04 April 2012, 07:52 AM
Indeed I could do that. that's a simple way ! Thank you for your replies it works perfectly.

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