Page 1 of 3 123 LastLast
Results 1 to 15 of 34

Thread: Controlling speed of travel along a spline/path

  1. #1

    Controlling speed of travel along a spline/path

    Hi all,

    Hopefully someone can help out cause this has been driving me nuts for a few days now.

    I have an object travelling along a spline. But what I want to be able to do is have the speed the object is travelling controlled by a null (Note: Speed, not distance).

    I was trying to figure out a way to link the Cruise Control motion plugin to a null, but have gotten nowhere. And then I found an old thread on here that uses the Item Motion node from Dponts nodes. Problem is, that particular node doesn't seem to have been updated in the latest LW11 release of the nodes, and the LW9-10 version kills Layout.

    Would anyone have a solution that works in 2015.3 ? I did think some kind of expression may work, but I have pretty much no knowledge of expressions. :-/

    I hope someone can help.

    Thanks
    TheMightyspud

  2. #2
    skeptic lertola2's Avatar
    Join Date
    Dec 2008
    Location
    New York City
    Posts
    1,154
    This might not be exactly what you are looking for but you can use Follower to reference a control null to animate along a spline:



    Click image for larger version. 

Name:	use_Follower_to_control_spline_control.jpg 
Views:	280 
Size:	226.1 KB 
ID:	142795
    use_Follower_to_control_spline_control.lws
    Last edited by lertola2; 09-10-2018 at 01:26 PM.

  3. #3

  4. #4
    Yeah I know about those already, but they don't do what I need it to. They control the position, what I want is to control the speed of travel along the spline.

    For example. I rotate the null 45 degrees. The object travels along the spline at 45 meters per second. Not 45 meters in distance.

    TheMightySpud

  5. #5
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,740
    Worley used to have a plugin called, I think, "Throttle"... it might have just been for rotation.

    Interesting problem.

    Perhaps HOW the dpkit motion node was setup would give us a starting place to suggest solutions.
    They only call it 'class warfare' when we fight back.
    Praise to Buddha! #resist
    Chard's Credo-"Documentation is PART of the Interface"
    Film the cops. Always FILM THE COPS. Use this app.

  6. #6
    You could try Path Animation AI
    http://thespread.faulknermano.com/_theoldspread/
    My opinions and comments do not represent those of my employer.
    www.ernestpchan.com
    www.zazzle.com/gopuggo

  7. #7
    PathAnimationIA again doesn't really do what I want it to.

    Worley's Polk had a few 'throttle' type plugins, but they're now very old, and not possible to get anymore. :-/

    ODTools does have something that would work, but alas you can only get it as part of the big pack, and tbh, we would haveta buy multiple copies and spending that money and not using any of the other plugins just seems daft to me tbh. :-/

    - - - Updated - - -

    As for HOW The Dpont example is set up. That's the big problem, I can't find any alternative to the Item Motion node that it relies on. :-/

  8. #8
    Super Member Qexit's Avatar
    Join Date
    Feb 2003
    Location
    Warrington, UK
    Posts
    1,197
    A little more information about exactly what you trying to do would probably help. For example, is the item going to travel at the same speed all along the spline or do you want to vary it ? Does it need to accelerate and decelerate as it travels along or is it just a set speed determined by the null ?
    Last edited by Qexit; 09-11-2018 at 06:16 AM.
    Kevin F Stubbs

    Remember...one size does NOT fit all

  9. #9
    It needs to vary throughout the animation. And will accelerate/decelerate (example, frame 0 - heading angle of controller null will be 0, giving the main object a speed of 0..........keyframe at frame 100 with heading angle of controller null = 60, speed of main null 60 m/s etc. So acceleration etc. will be dealt with by the controller null's heading.

  10. #10
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,740
    Is there a node that will output the LENGTH of a motion path?

    IOW, you point it at an Item, and it has an output that supplies the length of the motion path (which is a spline, mathematically) from the first keyframe to the last keyframe.

    IF you had that piece of information (and I have no expectation that it exists), with the addition of some (hah!) math you could probably create this function.

    (btw, that was yet another nice thing about Denis: once I suggested another output on a node and he implemented it in, like, two days. (It was some sort of percentage or total-count.))
    They only call it 'class warfare' when we fight back.
    Praise to Buddha! #resist
    Chard's Credo-"Documentation is PART of the Interface"
    Film the cops. Always FILM THE COPS. Use this app.

  11. #11
    Well finding out the length of the spline is relatively easy (just move the object to the end of it along the Z Axis as normal and make a note of the number at the end. I can GET the speed of the object travelling along the spline no problem with a little maths, problem comes when trying to accurately SET the speed.

  12. #12
    Registered User squarewulf's Avatar
    Join Date
    Aug 2014
    Location
    South Bend, Indiana
    Posts
    429
    So there is a way to do this, and I actually used a method like this for a ratcheting animation.

    User Prince Charming(bryphi77) came up with the idea of using particles and wind. Using the wind to drive a single particle - the wind acts as the accelerator. You animate the wind value then use the particles translation value to drive the vehicle.

    Old thread here: https://forums.newtek.com/showthread...cruise+control

    Video: https://www.youtube.com/watch?time_c...&v=RRncWuSl8bk
    Last edited by squarewulf; 09-12-2018 at 03:00 PM.

  13. #13
    Wow, that's kinda genius. But alas, I can't use that exact implementation as it relies on the Motion Info node from dpont, which doesn't work with 2015.3 (it's one that wasn't updated for LW11 ). But it has given me ideas to try

  14. #14
    Huh, okay, something weird. Was being stupid earlier. Apparently the Item Motion node does work in 2015.3 (as seen in that vid), but mine seems broken, and I've even re-downloaded it, but still doesn't work. Very odd, will poke around though and see if I can get it to work.

  15. #15
    Registered User squarewulf's Avatar
    Join Date
    Aug 2014
    Location
    South Bend, Indiana
    Posts
    429
    You should be able to get away with a good ol' Particle Info node instead.

Page 1 of 3 123 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •