How To Lock Particles On Emitter ???


#1

How To Lock Particles On Emitter ???
I have emitted particles from an object (Ex. Sphere) with zero speed so that they form the shape of the object… Now i do initial state for the particles and turn rate down to zero…
Now when i animate that object i want the particles to move along with the object…
You can use this to do a teapot dispersing into sand effect…
But how do i do this if the object is moving ???
I can parent the particles to the object… but then they will follow the animation of the object even after leaving the object surface… I can also give the particles goal… but then they seem to arrange themselves on the vertices of the object…
There is a straightforward feature called Lock On Emitter in 3DS Max
How can i achieve this in maya…
Please Please reply…
Thanks you


#2

you need to use goals but with use parentUV’s turned on in emitter. Emit your particles from your object.

then this code in creation and runtime

goalU = parentU;
goalV = parentV;

basically your telling maya where the particles are born on the surface is where they stick.

good luck

edit…this technique will also work for deforming geometry


#3

Add goalUV and parentUV attributes for the particle, turn ON the needParentUV attribute on the emitter make the emitter a goal and add this runtime expression
(assuming your particle is called particleShape1)

particleShape1.goalU = particleShape1.parentU;
particleShape1.goalV = particleShape1.parentV;

then go and tweak the goal smoothness. A value of 0 is boring, but seems to be what you want.


#4

Thank you mandark1011, Michiel for your replies…
I tried this but couldn’t achieve what i wanted exactly…
Now with goalUV and parentUV i can get the particles to form the shape of the object…
But when i have the goal weight to be zero they dont follow the animation of the object whereas when i have the goal weight to be 1 they are not affected by any force field
For Example - I have a animated teapot made out of particles… now that teapot goes through a turbulence field and all the particles get dispersed… In this case if i have the goal weight to be zero the particles wont follow the animation of the teapot… whereas if the goal weight is one the turbulence field wont effect them… i can keep the goal weight to be .5 or something but then the particles lag the animation of the teapot by a few frames… Also they are again attracted towards the teapot after dispersing…
So is there any way where the particles just follow the animation of the teapot 100% and then get dispersed as they pass through a turbulence field…
I hope you can help again
Thank you very much


#5

in this case you need to write a runtime expression on your goal weight. This works on a per particle basis. One of the tricks i use here is to make an event that doesnt actually collide then use the event to trigger my behavior. make a plane or shaped deforming object and make your particles collide with it but set the reilience to -1 then in runtime

if (event >= 1)
goalPP = 0;
else
goalPP = 1;

there are many ways to do this however i like this way because it gives me control on a visual basis of where and when my particles will change behavior.

good luck


#6

Hi
i tried this…
I created a plane and turned its resilience down to -1…
I created a collision event where no particles are emitted and the original particles dont die…
This is the expression i wrote in runtime

particleShape1.goalU = particleShape1.parentU;
particleShape1.goalV = particleShape1.parentV;
if (particleShape1.event0 >= 1)
particleShape1.goalPP = 0;
else
particleShape1.goalPP = 1;

(Actually i am doing this as i type :stuck_out_tongue: )

Now i have put a turbulance field… i have emitted these particles on a sphere and animated the sphere to go through this plane whose resilience is -1… But they dont seem to fly off even after passing through the plane… I there a step i am missing somewhere…


#7

can you attach the file ill take a look at it.

actually let me just make one up quick ill post in a few


#8

there you go hope this makes things clearer for you


#9

Thanks so much for that file… That solved the problem…
Cant thank you enough really…


#10

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