Article Focus: In this tutorial, Creative Cow contributing editor Carl Larsen shows you how to build an expression-based vehicle rig that automatically calculates the rotation of its wheels based on the movement of the vehicle chassis.
Thanks so much for this great tutorial. I just implemented your expressions in an animated bicycle video I had to make. Got the wheels and gears working great.
Do you have any suggestions on how to put a bike chain that wraps around the front and rear cogs? I have yet to figure out how to make one that reacts to the wheels/gears properly.
any help would be greatly appreciated!
bruce
To get the chain to work, you'd have to know the overall length of the chain and then tie the offset completion of your stroke to the circumference of the chain.
The length of the chain should be equal to 1/2 of the circumference of your first gear, plus 1/2 of the circumference of your second gear, plus two times the distance from the top of the second gear to the top of the first gear.
Have fun! I'm glad to hear you're putting the tutorial to good use.
Thanks Carl, your tutorial helped me out a lot.
I've applied the various expressions to a bicycle animation I have to do for a kids show about ratios.
I've set up all the wheels, cranks and gears to work with your expressions tied to the frame.
But do you have any suggestions for putting a chain on the bike that would react with the turning of the cranks?
I tried trapcode 3d stroke along the chain path, with the intention of offsetting a dotted stroke, (and perhaps attaching an expression to that offset), but it didn't work.
Any help would be greatly appreciated.
cheers,
bruce
2D and 3D are possible Erik, but I think I'm still mulling over how to do as simply as possible without having to bust out some calculus and dot products to make it happen.
Coming up on 10,000 articles in the Cow library, and I think this is the first one that mentions pi! And a tasty tutorial at that. :-) A very practical use of expressions, and very nicely handled even for a math-o-phobe like me. Keep 'em coming, Carl!
Brilliant! Thanks, Carl. I only wish I had known this trick a long time ago.
I wonder if it would be possible to also factor in the Y position so that if you're vehicle is traveling over steep hills or something the wheel rotation would still match.
Yeah! I can relate to that.
I think that most of the people here are familiar with the at least the basics and your tutorial really delivers tricks and techniques for pushing our knowledge further.
Something I really hold dear is a quick workflow. I would low to see more on that.
Glad to hear you enjoyed the tutorial. It's always a challenge to find a balance between being thorough versus just blasting through the details and getting to the fun stuff.
