View Full Version : Medical scene Particle Help. Please.

01 January 2005, 08:02 PM
I have several cross section scenes, this one slightly different, many of them have worked out with a simple solution.

What happens is a drug interacts with some receptors and forces the receptors to close.

I took these steps with every scene.

1. Allow particles to flow
2. Direct them with wind
3. Use a mesh cage and 'Fizz' to represent the place where particles should and shouldn't go.
4. Set up a pose mixer to open and close gates to prevent further particles from entering.
5. Hit play and watch.
6. Tweak and repeat.

This technique requires a lot of tweaking, but eventually works out nicely.

As you can see this one is fine;

But with this new scene it's not working out at all. Something just won't play nice.
I've been working on it for 2 days and i'm about to give up.

Below. Are the fizz gates that control when the particles stop flowing inside.

I have two questions.

Can I work a similar solution with Thinking Particles?

Do you know a better way than this?

01 January 2005, 08:25 PM
I'm just starting to get a (weak) grasp of TP, but yeah, I think it would be the better way to go. Off the top of my head I think I would direct the particles to the gates with a negative spherical gravity node. Then I'd use a getdata node to switch the particles to a new group (trapped) when they reach the x/y/z coordinates of the gate. Set the velocity of the trapped group to zero and set up a repulse/bounce node to repel/bounce the initial group off the trapped group. Not having tried it, I think that would take care of the particles.

Now you would want the gates to close when the trapped particles landed, and I'm not sure how/if you could do that with TP. Someone could probably suggest a way using TP with Xpresso, but worst case you do that part manually. The particles will look like they're bouncing off the gates because you set the repulse/bounce radius to fit the rough size of the gates.

01 January 2005, 08:41 PM
Nice shots

I will look into this further--but my first instict---dont use particles.

I have had to do almost the same exact thing b4--and find it easier if you draw paths that your particles will take, use align to spline on them, then instance them like crazy-altering position scale and rotation. This way you have total control of the particles. Sometimes particles are more trouble than they are worth. You can fill up the scene with random particles sort of moving towards the targets.

I'll get back to yo later...

01 January 2005, 08:48 PM
Great pointers from both of you, thank you.

With thinking particles I have little or no experience, It's something I should really experiment with and make use of. I'm going to need it in the coming months.

I've considered doing it manually Joel. It's a pain at first, but in the long run I've spent the best part of 2 days tweaking this scene for it not to work out, so it would served me well to do it myself.

The thing I like about particles is that you get a nice free flowing result as apposed to keyframing.

01 January 2005, 08:58 PM
Well--you can maybe just keyframe some of them--the crucial ones that bind and move through the gates--and then layer the scene with some real particles.

I've hit the same wall many times in the past. In the end--its all about figuring out how to get the job out the door. Many of the cool experiments that I've done just for fun, frustratingly enough, dont work for whatever reason when I have a practical use for them. Its on of those annoying laws of the 3d deadline. Things only seem to flow when you have all the time in the world.

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01 January 2006, 11:00 AM
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