Can I get a little help understanding ICE states?

[adrencg]

I've been trying to set up an effect, but without the result I'm looking for.

I have an object that's covered with particles. I want to use a null to move the particles off the object using the curlnoise framework node. I can do that by using modulate by null, but the problem is that any particles that take off will only fly while inside the radius of the null. I think I can use a State to "activate" the particle using a "test inside null" conditional, but I'm confused about what to set in the State compound.

here's the scene. I want anything inside the null to be affected by the curlnoise.



In the ICe tree, I'm not sure if I need to have the state compound there, because it seems to be built into the Simulation Root node, but I'm not sure.

[xsisupport]

edit: See this post for the basics of states and triggers.

You've got a state, but no trigger to get into that state.
You do have a trigger to get out of that state.
Simple State has no Simulate Particles node inside it.

Before you add in the fancy stuff, get a basic state transition working and use the colors to verify it.
For example: http://screencast.com/t/MeA6oBz01
I built that using the ICE menus.

[adrencg]

Thanks...I got the particles under the null to change color, but I still can't get the curlnoise to activate. Would that get plugged into a port on the State node, or in the Simulaiton Root node---and which port would it be? Execute on trigger?

[adrencg]

Got it finally. I wasn't setting the state ID's properly, now I'm understanding how this thing works. It takes me a little longer than most people, but eventually I'll figure it out.

[xsisupport]

Execute Every Frame on the State node

[adrencg]

Execute Every Frame on the State node

yeah that was the other thing I missed.

[adrencg]

Thanks for all the help Steve. I don't want to lead you down a black hole, but can you help me understand the next step?

I want to scale the particles down to 0 from their "launch" time after the curlnoise state takes effect -- not from their birth. The problem is knowing which trigger to use. This seems like it would be correct, and I've tried it multiple ways, but still nothing happens. I get the same non-result whether I plug into "on enter state" or "execute at every frame".

[adrencg]

I can definitely make it work if the null starts inside the particle grid, but not if I move it into the grid.

[origin]

Well if you trigger test for velocity just after curl noise, curl noise won't happen since you move to another state just after particle starts to move.

[adrencg]

Well if you trigger test for velocity just after curl noise, curl noise won't happen since you move to another state just after particle starts to move.

Ok, but this doesn't work either, because the null just makes a hole in the particle field. I can make the curlnoise work if there's no attempt at scaling the particles after they start flying.

I did get it kind of working by following your setup, except using "particle size" instead, but I don't know if using "state transition time" would be a good start for the sizing. It works perfectly when the null first hits the grid, but any time spent moving the null after that ----the particles still scale down, except they take exponentially longer as the null moves around. How could we use the actual launch time of each particle and use that as the parameter for scaling it down as it flies?

[origin]

Setup I posted works as you described. Make sure you have put right value for base_value in modulate value over compound (that is eg for scale its 1,1,1)

[adrencg]

Thanks, you're right that was it. So what's the difference between particle size and particle scale?

I'm going to leave the compound here in case anyone wants it.

[origin]

There is not much difference. But you can use scale as multipler for size.
So for example if you particles have random size at emission, you can then use scale to scale them down easily.
Otherwise you would have to save size of particle at emission in custom variable, and use this variable later (in your example with base_value)

[grahamef]

Size is a single value (e.g. radius of a sphere, length of a cube, etc.) but Scale lets you multiply that non-uniformly with separate XYZ values.