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View Full Version : MAYA Particle animation help please


aubone114
03-22-2007, 05:55 PM
hey guys, i wasnt sure where to post this thread, theres no dynamics section here. but im trying to do something specific with maya particles where wind blows fairy dust and it forms a word. im trying to get the wind to sort of start swiftly, and then slow down as it gets further away from the point of origin and i want the dust the sort of backdraft, in a whispy sort of fasion. im not too strong with expressions but it seems this may be the way to go, anyone know how i might approach this? thanks a lot.

lemonyfresh
03-23-2007, 06:54 PM
Create the words with curves, the curves running down the middle of the letter, if you want outlines just use the text editor. Then emmit the particles from the curve with either heavy damping or a small conserve value. Blow all the particles away with a tight turbulance field render out your frames and them comp them backwords.

aubone114
03-23-2007, 11:48 PM
ok cool, i will give that a try thanks, also i have another question. i have an instanced geometry attatched to the particles for software render purposes. i have an expression on the radiusPP attribute that reads:

particleShape.radiusPP = rand (.04, 1) ;

that does a nice job randomizing the size of each intance. but i also want to make the instance shrink over time, or as the age of the particle grows. what should i add to this expression to do this? or do i need to affect a different attribute to achieve this? thanks a lot in advance for any one that can answer this.

sergioduque
03-25-2007, 03:04 AM
i think you could go into "after creation" mode and add this:
particleShape.radiusPP -= <<5,5,5>> ;
or something on this lines.

lemonyfresh
03-25-2007, 09:42 PM
i think you could go into "after creation" mode and add this:
particleShape.radiusPP -= <<5,5,5>> ;
or something on this lines.


Ah, no...

Under your particle shape node in your add dynamic attributes tab create a general attribute of radiusPP. Create an expression in the raidusPP box that will appear in your Per Particle (Array) Attributes. Click one of the runtime radial button options and enter this expression:


particleShape1.radiusPP = particleShape1.radiusPP * .99 ;

This just takes the radius of every particle and decreases it by .01 for every frame after creation. I don't know how good you are with math, (I'm not) but pretty obviously the closer the number you are multiplying by is to the value of 1, the less you will decrease the radius per frame. The smaller this value the more rapidly your radius will decrease. For your purposes this value must be a number (n) 1> n >0, that is to say a number that falls between zero and one.

By the way, the product of this number will never reach zero, (so is is not useful for something like lifespan), and even though you will not be able to see the particles they are still being calculated so you should have their life span end at some point shortly after they are no longer visible. So just set up a lifespan PP that will have them dying out after emission for some set time that will be after they have shrunk beyond visibility.

I was just thinking though, since you will be creating this to comp backwords you will likely want your particles to actually grow over time rather than shrink (maybe not) but you would acheive this effect by using this expression:

particleShape1.radiusPP = particleShape1.radiusPP * 1.002 ;

Which applies the same principle as the previous expression just for the oppiset effect.

aubone114
03-26-2007, 02:35 AM
great, thanks for the help, ill give that a try.

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