Atom Project. <Need Dynamics Help>

# 1 16-05-2008 , 05:05 PM

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I am building a model for an atom. I want to show the atom of a hydrogen in which electron is revolving around the nucleus. as electron revolves it leaves its short trail which dies by fading.

Here what i have done till now.

Created a nurbs circle > created a particle emitter > animation of the emitter along the nurbs circle.

:headbang:

Guys please help me in making a trail of the revolving electron which dies before the electron passes through the same point again. I want my electron to be a sphere, Glowing, fading trail, along the arc of the orbit. I dont want tangential fading tail.

I will highly appreciate your help.

Thanks

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# 2 16-05-2008 , 07:54 PM

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I created this quick file for you to learn from that does what you want user added image

Instead of animating an emitter along the path of a circle, I simply created a sphere named "hydrogen" that rotates around a larger sphere called "Nucleus".

The small sphere rotates via a simple "time" expression applied to its' Y rotation attribute, rather than keyframing it along a path etc.

I then applied a simple surface emitter to the smaller sphere so particles would emit from it as it rotates around the larger sphere.

I then reduced the length of the "tail" by simply reducing the particle's lifespan.
So now the tail dies long before it reaches back around itself again user added image

To get the tail to "fade", I leave that learning lesson up to you user added image

HINT: "opacityPP" user added image

Good luck!

Attached Files

atom_demo.mb (59.8 KB, 354 views)

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 3 17-05-2008 , 02:51 AM

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HipHip Huray

Thanks a lot. Now it perfectly makes sense. Believe me i am been dreaming all night that how to do it. I now understand the concept.

user added image

Unfortunately i am unable to take the benefit of your attachment because when i try to open it maya gives me an error

"errors have occured while reading this scene that may result in data loss. Please check the script editor for details."

Can you please recheck the file and resend me. Either here or on my email

bilalbajwa2336@hotmail.com

I highly appreciate your help. This forum is awesome. I am learning a lot.

:attn:

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# 4 17-05-2008 , 11:30 AM

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The file is a Maya 8.5 Unl. file.

It will not open with Maya 8 or earlier, sorry user added image

I explained exactly what I did to make the file, so for you to create it yourself, it should only take you about 15-20 minutes user added image

1. Select your outer, rotating, smaller sphere.
2. Goto Particles > Emit From Object.
3. Adjust the particle emitter's rate and speed to taste.
4. Adjust the ParticleShape lifespan to die quickly by setting it to a low value.

Thats pretty much it.

For more details on working with particles and emitters, please check the help under Particles and Dynamics user added image

Good luck!

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 5 17-05-2008 , 11:40 AM

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:attn: Thanks for reply. I am been working on it and i am able to create what i wanted (thanks to you) except there is one problem. I cant get a sharp tail of the revolving electron. Do you know how to do that?

Also tell me what are "Particle Expressions"? Is this some kind of programming?? user added image

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# 6 17-05-2008 , 12:10 PM

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I cant get a sharp tail of the revolving electron. Do you know how to do that?

Originally Posted by

Well, the easiest way to achieve the "sharp" shape for the tail in the way that you require, is to:

1. Select the "tail" particleShape and apply a Radial field.
2. Parent the Radial Field to the smaller sphere
3. In the Attribute Editor, set the field to be a "volume" with a shape of "Sphere".
4. Position this field at roughly the distance behind the small sphere where you want the tail to be "sharp".
5. Adjust the fields' magnitude to a NEGATIVE value (i.e. -50 for example) so as to pull the particles into the shape of a point at the moment before they die user added image

Also tell me what are "Particle Expressions"? Is this some kind of programming??

Originally Posted by

For more detailed explanation on that exact question, see the following chapters in the Maya help:

Using Maya
__>General
_____>Mel and Expressions
________> Particle Expressions <-- user added image

Good luck!

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 7 17-05-2008 , 12:20 PM

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Also, I tried exporting the scene as a .MA AND a .fbx file just in case you might be able to IMPORT that into your version of Maya.

Here is the .MA file (Maya Ascii)

Attached Files

atomscenema.ma (73.9 KB, 284 views)

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 8 17-05-2008 , 12:21 PM

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....and here is the .FBX file:

Attached Files

atomscenefbx.rar (11.0 KB, 286 views)

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 9 17-05-2008 , 12:22 PM

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And last but not least, here is a sample pic I rendered to show you the result of this quick sample scene:

Attached Thumbnails

Click image for larger version

Name: test.jpg
Views: 341
Size: 9.7 KB
ID: 39030

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 10 17-05-2008 , 01:11 PM

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Duplicating orbit problem.

Thanks a lot for the help. I will try what you told me. It will hopefully work.

Once i have achieved the right tail. Please tell me how to duplicate the orbit with the electron + tail. to make more orbits for a complex atom but keeping the effects same as the for the first electron. Simple duplicate option is not working.

Thanks a lot for helping me.:attn:

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# 11 17-05-2008 , 04:09 PM

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Yes, simple duplication does not work for some things as there are far too many connections to deal with, etc.

Since you simply need the same type of particle and emitter settings, all you need to do is get your first emitter and particleShape acting and looking the way you want, then:

1. Open the attribute editor for your emitter.
2. At the top-right of the Attribute Editor dialog window, there is a "Presets" button.
3. Click and HOLD that button to create a preset for your current emitter settings.
4. Now, select your ParticleShape and follow steps 1-3 again.

Now, all you have to do is animate any more spheres you need, then simply apply a surface emitter to them, and apply your "Preset" you created earlier by opening the attribute editor for the NEW emitters and particleShapes, and holding-down the Preset button, and choosing "Replace" user added image

Good luck!

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 12 18-05-2008 , 01:49 AM

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Thanks a lot for your help. I will post again under this title if anything comes up.

Thanks a lot. I highly appreciate your help. :attn: :attn: :attn: :attn: :attn: :attn: :attn: :attn: :attn: :attn:

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# 13 18-05-2008 , 03:00 AM

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No problem user added image

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 14 18-05-2008 , 03:08 AM

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Animation Problem

Now i want to rotate my atom.

Electron is already revolving around the nucleus and i want it keep revolving while the atom rotates.

What i did was i grouped electron with nucleus. and then set key frame (360 deg) for the whole group. The problem is atom rotates fine but electrons stops revolving after one orbit.

Does my number of frames for revolving electron = total number of frames of my animation ?????

Please help me.!!!

user added image

:headbang: user added image

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# 15 18-05-2008 , 06:21 AM

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Well, without seeing your scene file I'm not sure about your setup.

But to get everything to follow the leader, so to speak, the rule of thumb to remember in Maya parenting, is:
"Children First, Parent last".

So, if you want everything to follow the position of your nucleus, or a master group node, then select everything you wish to be children, THEN select the PARENT last, and then group it user added image

To get things to rotate, say, on the Y axis WITHOUT worrying about keyframes, you can do the following:

1. Right-click on the objects Y rotation attribute in the channel box and choose "Expressions".
2. Apply the following: yourObjectRotateY = time*80;
(Sub "yourObject" for your actual object name)

If you MUST use keyframes, then you can also open the Graph Editor for your keyframed object, select the keys in the Graph editor view, and Goto: Curves, and set the Pre and Post infinity to Cycle, and your rotation will loop user added image

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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