the rollercoaster problem

the rollercoaster problem – a nice name for a problem you may encounter using motion paths in maya. named and explained by my maya instructor greg berridge lately, i hereby note down the solution offered.

first, the problem: draw a curve (using the ep or cv curve tool) which looks like a rollercoaster loop (hence the name) from the side view in maya.

now create an object which has a clear top/ down topology in order to see the problem you’re going to encounter (e.g. airplane, not a simple ball/ sphere). select the object and the curve and create a motion path (animate > motion paths > attach to motion path, default settings are fine). you may have to correct rotations of your object by selecting the curve and going into the motionPath1 tab of the attribute editor: tweak the front/ up axis/ inverse up etc. there if required.

now play through the frames and all looks as expected – except one issue: the airplane flips in the loop twice, which you definitely don’t want.

so, here’s the solution: create a second curve inside the first one. the easiest way is by just offsetting the first one: select the first curve, then edit curves > offset > offset curve (be sure you deactivate “cut loop”). here’s what you should get:

now create a locator, select the new path and make a motion path again. double check if the locator follows the path when playing through your frames. to finalize, select the airplane and change world up type to “object up” and type in “locator1″ in the now editable field at world up object. the airplane shouldn’t flip now any more.

this solution may help you to solve a lot of other troubles using motion paths. the more i dig into animation, the more i know: locators are the animator’s friends.

Tagged as: animation, maya, motion path