Steam Locomotive Wheelbase animation

  • Janine

    Approved the thread.
  • You will need many animations "encapsulated" in together (I don't know how to say it, but you will need a base animation under Main, then another under your base animation, another under that...etc).

    The base movement of the whole stuff is the movement of a specific point of one wheel (and thus that part that connects the wheels move around in circular directions). Though that's not a rotation around some axis but rather a transition in two dimensions, Y and Z. This two movements are the sine and cosine functions of the angle of the wheel. Since it consist two different movements, you have to have one under Main that moves the part in let's say Y dimension, and another under that which moves it in Z direction. This inner animation which you will attach the model animation to. Of course you need a little code to calculate these in the script (nothing serious, sin/cos(angle of the wheel) times some constant, according to the wheel size). Since these are transitions, you don't need to bother with pivots.

    (By the way this movement can be also made by two rotations. The part needs to rotate around the last wheels pivot, and under that animation you need another one, that rotates around the pivot of the end of the part - of course in the other direction, so if one is X=1, the other one is X=-1 axis. This way you don't have to calculate anything but have to add the pivots correctly).

    Then you have the part which connects to this part AND to the one that comes out of the cylinder in and out. This has to move around too but also rotate, so it should be under the animation described above and have a rotation, with a calculated value, again. Or it's "under" the animation described below, with a proper rotation, which should be calculated in a very complex way, or just tune it with a linear function (just like the animation of the pantographs of the GTN, the animations don't connect like this, both the upper part is just tuned with linear functions, in two directions).

    You also have the part that moves in and out the cylinder. That's a simple transition, no need to care about pivots. I think it's easier if it's "under" Main, and calculate the movement of it with a linear function (or it can connect to the animation above, if that one connects to the connector part, but that will get quite messy I think).

    There are some other parts (stuff the controls the valves of the cylinder...etc), but those are more complicated (they have to go under the movement of the wheel connector part, but rotate, move..etc).

  • I think, I couldn't describe all this better! ;-) Thank you very much, Bzmot332!

    For the coupling rod, I think the better solution is the second one: Attach it to one of the wheels (they should not get a spring animation, because it would make everything much more complicated) and turn it with the wheel alpha variable in the inverted direction. It's a similar solution like the inward swinging doors like the Berlin busses front door.

  • Don't worry, there are plenty big locomotives (well, more like electric than diesel) which have the same loco-style suspension :D