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daz1761
02-06-2011, 04:37 PM
Hello :help:

I am fairly new to lightwave but desperatly need a few expressions in my layout scene for my assignment.

I am going to have an engine with its cam cogs spinning and was wondering what expression to use so they are repeatedly rotating through out my 1 min video.

Also i am trying to sus out parenting my model car to my roller coaster track and was wondering when its done if there was an expression for the car to constantly move around the track.

Many thanks

nickdigital
02-06-2011, 07:00 PM
Also i am trying to sus out parenting my model car to my roller coaster track and was wondering when its done if there was an expression for the car to constantly move around the track.


http://newtek.com/forums/showthread.php?t=76730&highlight=roller+coaster

Or if you have the Modeler curve that made your track you can use that as a path constraint in Layout.

jeric_synergy
02-06-2011, 07:58 PM
Or if you have the Modeler curve that made your track you can use that as a path constraint in Layout.
That's a new one on me: can you elaborate?

Tnx!
++++++++

I am going to have an engine with its cam cogs spinning and was wondering what expression to use so they are repeatedly rotating through out my 1 min video.
If all they are doing is rotating, you don't need expressions, especially if they don't have changing speed or relationships between each other (i.e. just 'window dressing').

Set up a rotational speed you like, say over 30 frames, and in the GRAPH EDITOR, set the POST BEHAVIOR setting for that channel to LINEAR. In the graph you'll see the channel curve describe a straight line for the selected channel. For a rotation channel that means a constant rotational speed, forever.

Silkrooster
02-06-2011, 10:51 PM
Sounds like the expression is a requirement from his teacher.

jeric_synergy
02-06-2011, 11:53 PM
Oh, indeed: we should just send page #'s then. (They're hard enough to find!)

One thing: for just throwing up a bunch of eye candy, tying rotation or movement to the frame number or some fractional multiplier (e.g. "2.1") of the frame number is often enough-- I do that sorta cheesy thing in AE all the time. Throw in a COS or a SIN and walla, it oscillates!

daz1761
02-09-2011, 06:40 AM
http://newtek.com/forums/showthread.php?t=76730&highlight=roller+coaster

Or if you have the Modeler curve that made your track you can use that as a path constraint in Layout.

Cheers Guys, i thought i only had one reply, iv'e sorted the roller coaster by simplifying the track and keying in a null object then parenting the car with the null, very time consuming but i am only a beginner and will learn more quicker ways in the future :)

I do have the original paths from the spline draw and i am very interested in how you tell layout or an object to follow the path constraint?

Cheers

daz1761
02-09-2011, 06:44 AM
That's a new one on me: can you elaborate?

Tnx!
++++++++

If all they are doing is rotating, you don't need expressions, especially if they don't have changing speed or relationships between each other (i.e. just 'window dressing').

Set up a rotational speed you like, say over 30 frames, and in the GRAPH EDITOR, set the POST BEHAVIOR setting for that channel to LINEAR. In the graph you'll see the channel curve describe a straight line for the selected channel. For a rotation channel that means a constant rotational speed, forever.

Very Very good tip, thank you very much :) !!

Its just on the spec sheet on my assignment an expression but like you say i don't think i am using anything that complicated to use one. TBH, the tutor threw that in right at the end without even going through expressions, i do know a fair few After Effects expressions but thats it, we havnt had an awful lot of time so i might have to loose a few marks. Mind you your tip with the linear trick could be something i could include on my report :)

PS. I'm trying to get my pivot slap bang center with my cogs but cant quite pull it off?

Nangleator
02-09-2011, 07:00 AM
To get a motion from a curve in Modeler, use the Modeler plugin, PathToMotion. It saves a motion file. (You'll want points distributed evenly along that curve, most likely. Here's (http://www.newtek.com/forums/showthread.php?t=116655) a link to a post where I had to do that.)

In Layout, select your object, and choose File, Load Motion File. Chances are, the timing of your loaded motion doesn't match the proper length of your animation. (There's probably a trick to that, but I don't know what it is.) In Graph Editor, you can select all your keyframes (make sure all channels are selected first!) and stretch them in time, with "h" and the control key. You might want to turn on Fractional Frames in the options, first.