07 July 2003, 09:13 PM
I'll give you the quick answer so as not to waste your time, and a more detailed explanation should you be interested.
The Quick Answer:
No. You can not specify the frame spearation in LightWave. But Faulkermano's PathAnimationIA plug-in (http://thespread.ghostoutpost.com./) will let you do so. And to some degree, this can also be accomplished with the CurveConstraint motion modifier.
The Detailed Explanation:
When you import a motion file which was created from a spline in Modeler, Layout looks at the spline's points and creates keyframes at those exact X, Y, and Z positions. It creates one keyframe for every point in the spline, and spaces them five frames apart on the timeline. So a path with two points will yield two keyframes. One will be at frame 0 and the other at frame 5. A path with three points will yield three keyframes. One at frame 0, one at frame 5, and one at frame 10. And so on and so on.
There are two things which are important to note: First, there is no way to adjust the number of frames between points. You are stuck with a 5-frame separation. Second, because of the 5-frame separation, the distance between the points in your original spline will cause your motion to vary wildly. Points which are closer together will cause your object to move slower. Points which are further apart will cause your object to move faster. That can be a nightmare if you're trying to create a smooth, even motion from your exported path.
Faulkermano's plug-in can help resolve this problem. The core function of the PathAnimationIA plug-in is to allow one object to inherit the motion of another. In that sense, it's like LightWave's Follower plugin. But this plug-in goes beyond that by allowing you to modify that motion with a custom channel. So a path with 4 points would yield 15-frame animation. If you applied this path to a null, then applied the PathAnimationIA plug-in to your object, you could have it follow the null, then change the motion in the Graph Editor to go from 0 to 100% over any number of frames. Since there were four points in your spline, if you wanted the animation to last four frames, you could easily do this.
Now, you may be thinking that it's a lot of extra work to set up a null and put the PathAnimationIA plug-in to work. If all you want to do is specify the keyframe interval on your motion path, you'd be right. That's why Faulkermano included two more plug-ins: Export Custom Motion (from Modeler) and Import Custom Motion (into Layout). Check this out:
The Frame Separation field will allow you to do exactly that - specify how many frames should be placed between each keyframe. You're still going to get one keyframe for every point in your object. But this plug-in will allow you to determine how many inbetween frames are created.
I use the PathAnimationIA plug-in almost every day at work. It has proven to be a real lifesaver.
Now, there's another way to accomplish the same basic thing, and you can do it without 3rd party plug-ins. You can use the Curve Constraint motion modifier. The Curve Constraint modifier will allow your object to follow any curve, and it will allow you to specify the number of frames it takes to do so. If you went with this approach, you could save your object with the path on a separate layer. Once in Layout, add the Curve Constraint motion modifier to your object. Select the layer of your object containing the spline, and then set the Start Time and End Time to the match the number of points in your curve. I've tested this out and it works, but personally I think Faulkermano's plug-ins provide more accurate results.
Hope this helps!
07 July 2003, 10:38 PM
OK, thanx Steve :)
All that info was perfect.
Guess I'm going to have to stick with the method I'm using for the time being.
I'll go and check out this plugin you mention and see what I see.
I "am" actually working on something that has very special needs, that I can't get into here, but I need to have things work a certain way, i.e. the method in which I need to keep the motion even and smooth both at the same time while also allowing me to have control over "where" exactly I end up with keyframes "after" deleting those that I don't need.
Guess that probably sounds a bit confusing, maybe?, but I could explain better if you really need me to by personal email.
This is for a tutorial I am working on (which is why I can't totally get into what I am after) and I just needed to make sure of my findings before I went any further along with things.
So, thanx again for pretty much confirming what I suspected was the case.
And I'll go to flay and do a search.
01 January 2006, 06:00 PM
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