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Thread: Keyframed stretch of only some the polygons in an object

  1. #1
    Wary Lamb Rejoining Flock Scott Gammans's Avatar
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    Keyframed stretch of only some of the polygons in an object

    (I wasn't sure whether this question should go here or the Character Animation forum; mods please move this there if you think it'd be more suitable... thanks)

    I want to keyframe the stretch/growth of an object so that part of the object remains remains fixed at a particular location while the other end of the object stretches out. The image below illustrates what I'm trying to accomplish. I made this example in Modeler just to quickly sketch out what I'm trying to achieve, even though I realize the solution will probably be implemented mostly/wholly in Layout:

    Click image for larger version. 

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    My scene will have about 100 or so simple objects like the example above, all with different X-Y origins, stretching the same keyframed amount along the Z axis. I know there has to be a better way than keyframing each object's stretch manually, which would require also keyframing each object's position manually to keep one end planted in place while the other end strrrrrrretches out.

    Thanks!
    Last edited by Scott Gammans; 02-10-2020 at 11:25 PM. Reason: Corrected an error in grammar

  2. #2
    Registered User Oldcode's Avatar
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    How about copying your small object into another layer in Modeler, do the stretch, then use the Bkg to Morph tool in the Map menu to create a morph that you can control with an Envelope with Motion Mixer.

  3. #3
    Wary Lamb Rejoining Flock Scott Gammans's Avatar
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    Quote Originally Posted by Oldcode View Post
    How about copying your small object into another layer in Modeler, do the stretch, then use the Bkg to Morph tool in the Map menu to create a morph that you can control with an Envelope with Motion Mixer.
    Aha! Having never really delved into animation in Layout beyond simple keyframing, that solution didn't occur to me.

    I didn't find much in the way of video tutorials on how to use the "Background to Morph" tool, but after rereading the online documentation a couple of times I got it to work, once I realized that you probably meant to say Morph Mixer instead of Motion Mixer. The first time I tried this in Layout I also realized that I had the foreground and background layers reversed when I used the "Background to Morph" tool in Modeler; I had the stretched object in the foreground and the unstretched object in the background. This transposition worked in Layout, but only if I keyframed the "stretched" state of the object at 0% and the "unstretched" state of the object at 100%! LOL.

    In case anyone's following along at home (and also so I can refer to this in the future ), here are the exact steps I followed:

    1. In Modeler, open the model containing the object to be stretched. For this test I selected a simple model named boxes.lwo (which I've attached to this post as an example).
    2. Select the layer containing the object to be stretched and copy it to a second layer.
    3. Stretch (morph) the object in the second layer. This will be the 100% stretched end-state for the object. (Do NOT add or remove polygons or points in the stretched copy of the object; seven years of bad luck (and a messed up morph) will occur!)
    4. Select the first layer that contains the original unstretched object as the foreground layer.
    5. Select the second layer that contains the stretched (morphed) object as the background layer.
    6. With the two layers selected as described above, open the Background Layer to EndoMorph tool (Map->Morph->Background to Morph).
    7. Name your new endomorph and click OK. (Following LightWave's suggested naming guidelines, I called my endomorph "boxes.stretched".)
    8. Save your model.
    9. Open your scene in Layout and add the object layer containing the unstretched version of the object to your scene. (I didn't see any reason to add the layer that contains the stretched version of the object, but if there is a reason to include it, please let me know!) My example scene is named stretching_boxes_test.lws and is also attached to this post.
    10. Select the object and open the Properties dialog box.
    11. In the "Geometry" sub-tab of the "Primitive" tab, click the "Add Modifier" drop-down and select "Morph Mixer". Unless you've added additional morphs to the object you should see "Morph Mixer (1 endomorphs)" in the modifiers list.
    12. Double-click the "Morph Mixer" modifier to open the Morph Mixer dialog box.
    13. Drill down on the "Morph List" on the left-hand side of the dialog box and click the endomorph you created to select it. (In my example, since I named my endomorph "boxes.stretched" this was under boxes->stretched) You'll note on the right-hand side of the dialog box that the stretch strength is currently at 0.00%.
    14. You can visualize the stretching/morphing of the object by moving back and forth the slider that's left of the percentage display.
    15. To keyframe the stretch/morph effect, click the "E" button.


    Screenshots of animated result:
    Click image for larger version. 

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    Example object and scene:
    background_to_endomorph.zip

    This is exactly what I was looking for Oldcode, and now I know a little more about animation and endomorphs. Thank you!!

  4. #4
    Registered User Oldcode's Avatar
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    Yes, I meant to say MORPH Mixer! Do'H! Sorry about that, but also glad I could help.

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