PDA

View Full Version : What Am I doing wrong???



tddbr00
01-22-2008, 02:15 PM
I have null that is an HV emitter (on the left) its target is the null on the left. the wing in the middle is set to a collision/ object advanced/ stick. Probability 100% Bounce/bind power 100% All three objects are in the same group.

Why am I still getting that shoot off off the HV's?
And why is the trail that is correct not staying in line with the target null?

I am starting to not like emitters whether partigon, HV or wind.... :D

Steamthrower
01-22-2008, 02:25 PM
Sorry - you lost me in the middle of the second sentence. Let me try to get it straight.

You have an emitter on the left. You have a target on the right. In the center you have an object.

Okay, now - what do you mean by "shoot off"? Do you mean that the particles aren't going in the direction you want? Or are they deflecting off the object in the center and you don't want that? Do you have wind turned on?

tddbr00
01-22-2008, 02:49 PM
Sorry - you lost me in the middle of the second sentence. Let me try to get it straight.

You have an emitter on the left. You have a target on the right. In the center you have an object.

Okay, now - what do you mean by "shoot off"? Do you mean that the particles aren't going in the direction you want? Or are they deflecting off the object in the center and you don't want that? Do you have wind turned on?

Yes emitter on the left, target null on the right with an object in between. the "shoot off" is that stream of particles that are hitting the object and going up into the air not flowing over the contour of the object (which is an airplane wing). then when the particles (at least the ones that ARE following the contour)are passed the object, they continue downward and not toward the target null.

Surrealist.
01-22-2008, 03:44 PM
I don't think you aren't doing anything wrong exactly. I think that is what would happen with the particles if they hit something. They may start out in the direction of the target but that does not mean they have to keep going. Seems to me that all a target is, is a way to direct the particles other than xyz. Notice it is in the motion tab under the XYZ and it overrides it, making the only control for speed being the velocity percentage input.

Also if you notice (without the collision) the particles head toward the pivot of the target creating a cone effect. I don't know if you can override this or not but it sounds like you are trying to create a wind tunnel effect or show how particles would flow over the wing.

If so how about using the technique in this video with wind (ftp://ftp.newtek.com/multimedia/movies/w3dw/waterpipe.mov)?

tddbr00
01-22-2008, 04:00 PM
I don't think you aren't doing anything wrong exactly. I think that is what would happen with the particles if they hit something. They may start out in the direction of the target but that does not mean they have to keep going. Seems to me that all a target is, is a way to direct the particles other than xyz. Notice it is in the motion tab under the XYZ and it overrides it, making the only control for speed being the velocity percentage input.

Also if you notice (without the collision) the particles head toward the pivot of the target creating a cone effect. I don't know if you can override this or not but it sounds like you are trying to create a wind tunnel effect or show how particles would flow over the wing.

If so how about using the technique in this video with wind (ftp://ftp.newtek.com/multimedia/movies/w3dw/waterpipe.mov)?

Actually thats exactly what Im doing...a wind tunnel and showing the way air moves over an airplane wing.

Surrealist.
01-22-2008, 06:51 PM
Actually thats exactly what Im doing...a wind tunnel and showing the way air moves over an airplane wing.


Then yes, I'd bag the target idea and set up a wind path or use wind with the wing as collision. :)

Hopper
01-22-2008, 08:03 PM
Couldn't you simply rotate the entire animation 90 degrees and use gravity?
If you wanted the particles to contour to the airfoil, you could use two wind emitters on either side to "blow" the particles back together.

Another way would be to simply create two "tubes" as collision objects and blow your particles through them. Then make sure the tubes aren't seen by the camera or any other rendering options. Off course the tubes would conform to the contour and be a bit more flat.

...or did I totally miss the boat on that one.

An example of the whole tunnel thing (I think this could work):

William Vaughan's Water Pipe Tutorial (ftp://ftp.newtek.com/multimedia/movies/w3dw/waterpipe.mov)

Surrealist.
01-22-2008, 08:44 PM
Couldn't you simply rotate the entire animation 90 degrees and use gravity?
[/URL]

Gravity can be + or - on X Y or Z. :yingyang:

Hopper
01-22-2008, 08:46 PM
Something like this perhaps?

Note: It's not great, I just cranked it out fast, so it's not exactly a Picasso. I flipped the poly's for easier viewing
:D

Just put your emitter on one end and some wind ...

Hopper
01-22-2008, 09:07 PM
Gravity can be + or - on X Y or Z. :yingyang:
Yeah .. I had to smack myself after it hit me 2 minutes later. Sometimes it's hard to break that reality barrier. I think this is why my lighting always sux.

:bangwall:

Surrealist.
01-22-2008, 10:16 PM
LOL! Know what you mean. :)

tddbr00
01-23-2008, 07:10 AM
Something like this perhaps?

Note: It's not great, I just cranked it out fast, so it's not exactly a Picasso. I flipped the poly's for easier viewing
:D

Just put your emitter on one end and some wind ...

Hopperz
that is not a bad idea at all...im going to have to try that one out today. I pretty much gave up yesterday. I need to add multiple streams of airflow in the animation, anyone suggest why when I set the interaction of the particles they dont actually interact with each other...i.e. I set the interaction to bounce but they dont bounce they continue on their merry little way. not to qoute Ghostbusters but "Dont cross the streams!"

dwburman
01-23-2008, 07:53 AM
If all you want to do represent air moving over an airfoil you could do this with moving a texture (image map or procedural) through a morphed (or boned) polygon(s).

If you want to do a wind tunnel simulation, you're getting into fluid dynamics and LW doesn't have a fluids engine. You can fake it, of course, using the methods listed in here. I think Dynamite might be able to do what you want.

colkai
01-24-2008, 02:38 AM
Hopperz idea is very similar to an old "wind tunnel" scene.

stib
01-24-2008, 05:09 AM
Hopperz
that is not a bad idea at all...im going to have to try that one out today. I pretty much gave up yesterday. I need to add multiple streams of airflow in the animation, anyone suggest why when I set the interaction of the particles they dont actually interact with each other...i.e. I set the interaction to bounce but they dont bounce they continue on their merry little way. not to qoute Ghostbusters but "Dont cross the streams!"

You have to manually tell dynamics to calculate when you're including self - interaction in the dynamic system, so hit the calculate button and they should start shioving and bouncing and crowding. And you have to save the calculations before you render the sequence too, or it will ignore any particle interaction. And another thing that you have to do to get particles to interact with themselves is to give them some size. Check all these and see how you go.

Dynamite (commercial plugin here (http://www.cantarcan.com/dynamite/)) seems to have pretty good collisions with fluids, I'm not sure how physically accurate it is, but it looks pretty good. Blender (http://www.blender.org/) is another option, it does good fluids. Only problem is integrating it with LW and working out how to use it.

Blender fluids tute (http://wiki.blender.org/index.php/SoCFluidTutorial1).