I was wondering if I can setup one NLA path animation and assign a complete sequence of animation action strips to a “path” for one part of an animation sequence. Then later I can add more NLA action paths as I need for various changes in a characters motion or position.
Say one character is walking down a sidewalk “path” as another character is backing a truck out of an adjoining alley “path”. The walking characters path bends around the character backing out of the alley. Something drops off of the truck and the walking characters turns around stops and looks back. The character in the truck walks on a new “path” out of the truck and starts to pick up the fallen object. The walking character runs over on his original “path” to join the truck character. Then they both are joined to a new “path” for lifting the object and taking it back to the truck and lifting it onto the truck.
-The end.
Is this type path animation of setup possible with the NLA system?
I’m not entirely sure you have to have multiple paths. Have you used a speed IPO on your paths ? You can stop, slow up, reverse, etc. your model’s movement on the path with a path’s Speed IPO curve.
If you really had to have multiple paths, would it be possibly to use a Frame Changed script link to reparent you model to a different path on a specific frame ? Or how about using Follow Path constraints ? I’m not sure how well the follow path constraints play with the NLA though, if you’re using the Use Path options for walk cycles and such.
Another option would be to just break the rendering into several takes. Render the animation up until you need to change paths and then do a new scene with the models parented to the new paths.
I’m approaching some of this stuff soon, so have thought about it, but haven’t played with it yet. So, just a few ideas of how I was thinking about solving these problems when I finally get to running into them.
This is mostly some ideas that I’m working out as I get into the basic NLA stuff and practice using the NLA tools. I don’t know Python yet so the scripts are out. I could break things up into different scenes and add them together later on. I’m not to clear on how Speed IPO curves work with the NLA Editor yet. Thanks for the tips.
Pretty simple to use the Speed IPOs on paths. Select the path, get an IPO window up somewhere and set the IPO type to Path. Make sure Speed is selected on the right hand side of the graph and the CTRL-LeftClick your first point of the curve. Keep CTRL-LeftClicking more points or SHIFT-DKEY duplicate existing ones. I also use NKEY a lot here in edit mode to set exact values for the points.
The X axis is the frame, so one side effect of using a Speed IPO on the path is that the PathLength parameter under F9 for the path doesn’t affect the path any more.
The Y axis is the position along the path, valid values are between 0.0 (beginning of the path) and 1.0 (end of the path), inclusive.
So, if you plot a point at 1, 0.0 (x/y), that means that on the first frame, your model would be at the beginning of the path. If you plot another point at 100,1.0 your model is at the end of the path at frame 100.
With a point at 25, 0.5 and others at 50,0.25 and 75, 0.25 added to those above, your model would start at the beginning of the path. Then by frame 25 would be half way along the path. It would then move back towards the beginning of the path to 1/4th the way a long by frame 50 and stay there stationary until frame 75 when it would then move to the end of the path by frame 100.
Combine those points above with some nice bezier curve adjustments to ease in the velocity changes and you can make things look pretty natural.
The great thing about using something like this with the NLA and walk cycles is that your walk cycle animation will speed up and slow up appropriately to cover the correct distance in the number of frames available. Pretty powerful.