Integrating 3D models with photography
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# 1 09-06-2003 , 01:15 AM
GreyFox's Avatar
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Need help with: Tank Track along a motion trail

I'm making a Tank track, and I want to use a CV Curve with a Motion Trail to position, and animate the track.

But I'm having problems with making it work.

When I assign more then one "track part" to the motion path they are all placed on the same position, how do I get them to be placed right after each other?

And will it be a problem with the fact that all but the first "track part" are instances?

I will probably have more questions after I get this part to work...

# 2 09-06-2003 , 01:55 AM
Darkware's Avatar
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Select all pieces of the tank, then choose Edit.Group. Now assign a motion trial to the group.

# 3 09-06-2003 , 02:30 PM
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I've tried that, but then the track moves as one long piece and each part doesn't follow the curve individually as they should.

# 4 10-06-2003 , 12:22 AM
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recently i found a good workaround on how to animate it (thanx to highend),

what i did is, i have a track model with 56 tread, i put a curve along it so that i can use it as a spline curve it need to be rebuilt uniform with its parameter range from 1 to 0, make a skeleton that would be bound by the treads and must match where your curve lies, the no. of skeleton must be equal to the no. of treads and be sure that it is exactly where you will bound the treads. then i made an ik spline using the curve and the joints that was made, make all ik creation options uncheck except the "root on curve", in the outliner select first the root and then cntrol select the last joint, control select the curve. rigid bind the treads to the skeleton, rename your ik TRACK.

make a locator rename it TRACKCONTROL, add an attribute and name it like as CONTROLLER,
this is the expression:

TRACK.offset = ( ceil (frame / -TRACKCONTROL.CONTROLLER )) - ( frame / -TRACKCONTROL.CONTROLLER );

this expression will loop the offset of the ik spline,

if you have 0 to 100 frames in your time slider and you want your track to revolve 4 times then, 100 / 4 = 25, 25 will be your no. to your CONTROLLER.

hope this helps


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Last edited by olivermagno; 10-06-2003 at 12:25 AM.
# 5 10-06-2003 , 12:35 AM
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and here is th sample scene.

Attached Files
File Type: ma track.ma (324.9 KB, 385 views)

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our decisions-not the conditions of our lives
determine our destiny.
# 6 10-06-2003 , 12:37 AM
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track sample

and here is the sample scene.

Attached Files
File Type: ma track.ma (1.04 MB, 394 views)

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our decisions-not the conditions of our lives
determine our destiny.
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