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Thread: Rotation problems

  1. #1
    Creator of the Strange Skinner3D's Avatar
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    Rotation problems

    On my p-61 (which is shown on another thread) I need to rotate things like landing gear bay doors, flaps, ailerons, etc. All of which do not lie nicely along the x,y, or z axis. How do I go about making these work? I would like to use morph maps, but I can't get the pieces to rotate along a certain edge.
    Is there a way to define a group of points or edges to act as a hinge group or do I need to do something other than morph maps?
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  2. #2
    Cow Orker cagey5's Avatar
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    I would add a null for each rotation item, line that up on the required axis and parent to it.
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  3. #3
    Creator of the Strange Skinner3D's Avatar
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    That is a good idea and I will try it.

    Is there anyway to do this in modeler?
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  4. #4
    Cow Orker cagey5's Avatar
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    Not so far as I am aware. You can move pivot points for each later but not rotate them. Until someone tells me otherwise.
    But it's dead simple to do in Layout anyhow.
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  5. #5
    Cow Orker cagey5's Avatar
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    That should of course of read '.... for each layer ....' 5 minute edit limit.... grumble, grumble.
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    Dreamer Ztreem's Avatar
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    Quote Originally Posted by cagey5
    Not so far as I am aware. You can move pivot points for each later but not rotate them. Until someone tells me otherwise.
    But it's dead simple to do in Layout anyhow.
    You can rotate around pivot points in modeler, just change mode to pivot instead of mouse. That way you can test if your pivot point is in a good position.

  7. #7
    Cow Orker cagey5's Avatar
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    I understand that, but you can't actually rotate the pivot point as far as I know.
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  8. #8
    Quote Originally Posted by Skinner3D
    On my p-61 (which is shown on another thread) I need to rotate things like landing gear bay doors, flaps, ailerons, etc. All of which do not lie nicely along the x,y, or z axis. How do I go about making these work? I would like to use morph maps, but I can't get the pieces to rotate along a certain edge.
    Is there a way to define a group of points or edges to act as a hinge group or do I need to do something other than morph maps?
    It seems to me that the easiest way than nulls or even bones is to set it up right from modeler.

    Since the angles of the wings are oblige and thus the pivot points will be so - in layout - you need to set up your moving parts so that they are in parallel/perpendicular alignment with XYZ first. This will have them rotating from a native HPB that is in alignment with the part. (Tip: Use numeric pannel to bump part at less than 1 degree so it is in alignment. Another tool is rotate to ground.)

    Then they should be centered (or pivot point adjusted) so that they will rotate from the proper axis point when positioned on the wing in layout.

    In layout simply position it to the oblique angle of the plane part (wing etc.)

    (It is much easier to position a part. A null has to be parented and unparented to readjust the part. Bones need to be activated and unactivated to keep testing the rotation.) Otherwise the rotation will be off from the orientation of the part.

    Once positioned switch to Coordinate Local Axes and it will rotate properly from its position. To readjust simply set it back to parent and rotate then to local to test and for animation.

    To me that is much less work in the long run and you have less things cluttering up your animation.
    Last edited by Surrealist.; 08-26-2007 at 10:46 PM.

  9. #9
    Super Member SplineGod's Avatar
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    Some things you can use endomorphs on since they dont rotate much. Others you can parent to nulls and rotate the nulls into the proper positions. Its also possible to use bones as well. Each part can have its own set of bones or you can make everything a single piece and use bones and endomorphs.

  10. #10
    Creator of the Strange Skinner3D's Avatar
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    Thanks guys that helps a lot

    From my limited knowledge all of these different methods will work with expressions, right?
    Which one would be best? I am trying to get it so that all I have to do is animate the path that the plane follows, and the control surfaces are automatically adjusted to make it look real. (Attempting to follow the tutorial from Inside Lightwave 7)

    Thanks again for the help so far

    If expressions work like I think that they do, then the above question might be a very stupid question
    Every time I think about Marvin the Paranoid Android, I realize just how good my life is.

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  11. #11
    The Expressions will simply automate or trigger rotations and such based on some other input so that would work fine providing you have your rotations set up correct. Once you have that then all will be fine. A bank rotation of the plane can trigger each flap and so on.

    Mess around with a simple plane wing and a flap just as a simple way to test it and you'll see exactly how the oblique angle really needs attention based on how I described the set up.

    If it were me - especially with expressions - I would try to keep it simple and have less controllers.

  12. #12
    Creator of the Strange Skinner3D's Avatar
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    I am stuck again

    I got the front landing gear doors to rotate, but the flaps are giving me a headache. Is there anyway to use more than one pivot point on an object? Or is there anyway to fix points? When I set up the flap it wont stay in its socket even when I only manipulate one rotation axis.
    Every time I think about Marvin the Paranoid Android, I realize just how good my life is.

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  13. #13
    Super Member SplineGod's Avatar
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    Lets say you would normall have the flaps parented to the wings but you need to rotate the flaps because the wings arent straight out from the sides and are swept back.
    Create a null and parent the flap to it. Place the null and rotate it so that flaps in the right spot. Now when you pivot the flap it will do so relative to the null.
    If you need to have more control, parent the first null to another null and so on.

  14. #14
    Creator of the Strange Skinner3D's Avatar
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    My frustration levels have offically reached the point at which I almost give up
    Anyway, here is a zip file with a basic scene and part of my p-61. I set up one of the flaps, and it is the best I have see so far (by just rotating the green handle), but it still has problems especially on the outboard end of the flap.
    Could some of you please download this and either see what I am doing wrong or try out some of the things that you have been suggesting?
    If you get it working so that the two corners of the flap that are not on the edge of the wing don't move using simple rotation (because I have to express it later ) I will be forever grateful.
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    Every time I think about Marvin the Paranoid Android, I realize just how good my life is.

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  15. #15
    Super Member SplineGod's Avatar
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    Theres a couple of things I would look at.
    I looked at some blueprints and they indicate that the line along the flap is straight not curved. If its curved theres no way to get it to rotate and look correct.
    The 2nd thing is that where you have the null probably isnt quite correct.
    You have to worry about lining it up to rotate correctly from above along the edge of the flap AND from the front view along the edge of the flap since the wings arent straight out to the sides.

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