Page 2 of 3 FirstFirst 123 LastLast
Results 16 to 30 of 34

Thread: Controlling speed of travel along a spline/path

  1. #16
    skeptic lertola2's Avatar
    Join Date
    Dec 2008
    Location
    New York City
    Posts
    1,137
    The idea of using wind to push a particle to accumulate a value is very interesting. I have been playing with it and I think the attached setup works. It needs DP Kit particle info so I don't know if we can get something like this to work in Lightwave 2018. In the attached scene the Z direction of a Wind object uses Channel Follower to follow the heading of a control null. A particle emitter emits a single particle which is blown in the Z by the wind. A null uses DP Kit Particle Info node to follow the position of the particle. And the light uses Follower to follow the Z position of the null to animate it along the spline. I also added Cloth FX to the control null so that the calculate button would be available instead of having to select the emitter after each edit to see it. Quite convoluted.

    Click image for larger version. 

Name:	use_wind_to_accumulate_value.gif 
Views:	41 
Size:	707.2 KB 
ID:	142811
    use_particle_wind_to_accumulate_valeu_v001.lws
    Last edited by lertola2; 09-13-2018 at 03:00 PM.

  2. #17
    Registered User squarewulf's Avatar
    Join Date
    Aug 2014
    Location
    South Bend, Indiana
    Posts
    420
    Something like this seems like it would be very easy to script... kind of surprised there is no "speed" plugin already.

  3. #18
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,737
    Quote Originally Posted by TheMightySpud View Post
    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.
    ?? Yes, if the spline path is straight, and if it is not a motion path with TCB or any interpolation at its keyframes. @^@
    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.

  4. #19
    @Lertola2 - I had a quick play around with the particle idea (having gotten the Motion Info node working finally), but the problem I had was getting the kind of control I need (same reason I haven't used bullet 'car rig' tools)

    @Jeric - Using the built in Spline the path is technically always 'straight' as you only edit the Z axis to make the object travel.

    @Squarewolf - I did have the thought of editing the Cruise Control lscript that comes with LW to add in functionality to be able to select a Null and Axis to control the speed, but I'm not a scripter/coder so it's kinda baffling to me. lol.

    I am however going to have a look at the Maths involved in Cruise Control and see if I can recreate it using nodes.

  5. #20
    Registered User squarewulf's Avatar
    Join Date
    Aug 2014
    Location
    South Bend, Indiana
    Posts
    420
    Quote Originally Posted by TheMightySpud View Post
    I am however going to have a look at the Maths involved in Cruise Control and see if I can recreate it using nodes.
    I don't know much about coding but I don't think that will work, you need to be able to accumulate value over time and the only way I think that is possible is with particles or bullet.

  6. #21
    Super Member XswampyX's Avatar
    Join Date
    Aug 2010
    Location
    Kernow
    Posts
    2,078
    Quote Originally Posted by squarewulf View Post
    I don't know much about coding but I don't think that will work, you need to be able to accumulate value over time and the only way I think that is possible is with particles or bullet.
    Yep. If I drive from Plymouth to London in four hours, then how fast was I travelling through Exeter, in rush hour?

    No amount of maths is going to give you the correct result, given the limited information.
    Attached Files Attached Files
    Last edited by XswampyX; 09-14-2018 at 04:16 PM.

  7. #22
    Dreamer Ztreem's Avatar
    Join Date
    Jun 2003
    Location
    Sweden
    Posts
    4,164
    Quote Originally Posted by TheMightySpud View Post
    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
    You say speed not disstance? you know that speed is defined by distance over time, don't you?

    As you do this in Lightwave I assume that it's going to end up as an animation and not a realtime app, so why do you need to control the speed with a null? it is possible but sometimes its just as easy to work straight in the graph editor.

    Here's an example with spline control. I hope it can help or give ideas.
    Click image for larger version. 

Name:	2018-09-14_23-12-09.gif 
Views:	57 
Size:	1.73 MB 
ID:	142815

  8. #23
    Super Member XswampyX's Avatar
    Join Date
    Aug 2010
    Location
    Kernow
    Posts
    2,078
    Quote Originally Posted by Ztreem View Post
    You say speed not disstance? you know that speed is defined by distance over time, don't you?

    As you do this in Lightwave I assume that it's going to end up as an animation and not a realtime app, so why do you need to control the speed with a null? it is possible but sometimes its just as easy to work straight in the graph editor.

    Here's an example with spline control. I hope it can help or give ideas.
    Click image for larger version. 

Name:	2018-09-14_23-12-09.gif 
Views:	57 
Size:	1.73 MB 
ID:	142815
    I think we might have a winner!

  9. #24
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,737
    It's possible the OP was anticipating many revisions and just wanted an easy control to vary the speed, versus setting keyframes.
    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.

  10. #25
    Super Member Qexit's Avatar
    Join Date
    Feb 2003
    Location
    Warrington, UK
    Posts
    1,118
    It's a pity Worley's plugins are no longer available as there is one in the Polk collection called VelAccel that would probably meet the OPs needs. It was part of the Henry Clay Collection that came as a bonus. The full description was:

    VelAccel

    Allows you to keyframe object velocities instead of positions. This makes smooth parabolic arcs easy (negative Y accel, constant X and Z velocity.) It can also be useful to make smooth accelerations of cars, since keyframing a smooth acceleration is hard.

    Click image for larger version. 

Name:	VelAccel Panels 01.jpg 
Views:	22 
Size:	239.5 KB 
ID:	142821

    I never had a use for it myself but just loaded it up in LW2018.0.6 after dusting off my old USB dongle so it would at least try to work.
    Kevin F Stubbs

    Remember...one size does NOT fit all

  11. #26
    Dreamer Ztreem's Avatar
    Join Date
    Jun 2003
    Location
    Sweden
    Posts
    4,164
    Quote Originally Posted by jeric_synergy View Post
    It's possible the OP was anticipating many revisions and just wanted an easy control to vary the speed, versus setting keyframes.
    Yes, but if you use a null for doing so you only transfer the keyframes to that null instead of your object. You don’t really gain anything, sometimes its easy to overthink and complicate things instead of just do it.
    I don’t say there isn’t a reason or that you should not do it but you should think it through before you do it.

  12. #27
    Dreamer Ztreem's Avatar
    Join Date
    Jun 2003
    Location
    Sweden
    Posts
    4,164
    Quote Originally Posted by Qexit View Post
    It can also be useful to make smooth accelerations of cars, since keyframing a smooth acceleration is hard.
    Why is that hard? Its very easy, I think. Please enlighten me why its hard.

  13. #28
    Super Member Qexit's Avatar
    Join Date
    Feb 2003
    Location
    Warrington, UK
    Posts
    1,118
    Quote Originally Posted by Ztreem View Post
    Why is that hard? Its very easy, I think. Please enlighten me why its hard.
    I have no idea. That line is simply a direct copy of the plugin description from the manual which is dated June 25, 1998
    Last edited by Qexit; 09-15-2018 at 05:02 PM.
    Kevin F Stubbs

    Remember...one size does NOT fit all

  14. #29
    Dreamer Ztreem's Avatar
    Join Date
    Jun 2003
    Location
    Sweden
    Posts
    4,164
    Quote Originally Posted by Qexit View Post
    I have no idea. That line is simply a direct copy of the plugin description from the manual which is dated June 25, 1998
    Ah OK. At that time I can understand it was hard but now the tools are a lot better and its not that hard anymore.

  15. #30
    Axes grinder- Dongle #99
    Join Date
    Jul 2003
    Location
    Seattle
    Posts
    14,737
    Quote Originally Posted by Ztreem View Post
    Yes, but if you use a null for doing so you only transfer the keyframes to that null instead of your object. You don’t really gain anything, sometimes its easy to overthink and complicate things instead of just do it.
    I don’t say there isn’t a reason or that you should not do it but you should think it through before you do it.
    Another possibility is that the null controlled MANY other items.

    I can certainly see how this would be convenient if one were, for example, animating a bird's eye view of a car race with a basically circular track, but not an actual circle. Each car would get a "throttle", and blah blah blah. Of course, by the time you got this system working, you could have animated it w/keyframes three times over.

    Still, it'd be nice to know if the overall system is flexible enough to accommodate such constructions.
    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.

Page 2 of 3 FirstFirst 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
  •