spinning blades

basshole · Post by **basshole** » Thu Jun 18, 2009 4:07 am

I know this should be simple, but it doesn't want to work right.

So, I have a blade, like a table saw blade. I want it to spin, and be a looping action.

is a vector layer inside a bone layer. There is a single bone with its pivot point right in the center of the blade, so when the bone is rotated, blade spins.

So I create an action, and in this action, it has a starting position on frame 1, and then, say 8 frames later, it's spun halfway through a revolution. By frame 16, it should be back at its start position.

I tried key framing this a couple ways, all with no success. I tried putting a key at the halfway point through the revolution, and looping it from there back to the first frame. That of course makes it go BACK the way it came instead of continuing to rotate in the same direction.

Also tried one key at the halfway point, and another when it again reaches the start point. Same issue as above.

Also tried a key at halfway point, the 3/4 point, and then at the start point. Just sort of jitters back and forth.

I'm assuming this has to do with ASP not understanding that I want the bone to continually rotate in the same direction.

I also tried doing point rotation on the blades. This does the same thing (back and forth instead of continuous rotation), but also, for some reason, the radius of the circle described by the blades SHRINKS as I rotate that set of points through a revolution.

I know this is dumb, but I can't figure it out. Any ideas?

Genete · Post by **Genete** » Thu Jun 18, 2009 6:05 am

To have a clue of what's happening click on the subject bone using the bone angle tool. Then look to the angle entry box in the top of the main window and watch the angle value to see what's doing. Confirm if the bone angle does a linear angle movement or a "boomerang" or what. Also check out the graphic timeline to see the angle channel of that bone and its curve.
If you're on ASP 5.6 I can load the file and see what's happening but it is a really weird bug.

Try to enter a numerical value in the bone angle value entry, like 720 (two turns) and see what happen.
-G

basshole · Post by **basshole** » Thu Jun 18, 2009 6:14 am

Ah. See, that's one of those tools I've never even played with. Live and learn.

basshole · Post by **basshole** » Thu Jun 18, 2009 8:14 am

Okay, this is weird. Just watching it in the action timeline, it never goes through the cycle. . .it just keeps going from the frame 1 to 2 and then back, like I have a cycle command on 2 (which I don't). I even took the cycle command OFF so it's just 8 frames and then no more keys, and it still does it ! This isn't just a timeline thing. . .I export a movie and it does the same thing. I thought maybe I was making it rotate too fast and freaking AS out or something, so I tried making it take a full second for a revolution (24 frames), and I can still see it changing direction about halfway through. It spins one way, then turns around and spins the other. I DID set the last key to an angle of 700 (the start angle is 340), and this 700 key is where it cycles back to the first frame.

Mikdog · Post by **Mikdog** » Thu Jun 18, 2009 12:22 pm

Don't rotate the points. Rotate the layer. Put the origin of the layer in the middle of the blade. That's the cross-hair thing. Do all of this on frame 0 mind you. Then, press 3 to access the rotate layer button. On frame one, enter 0 degrees in the dialog box. Then, say, 8 frames later, enter 360 degrees in the dialog box, or -360, depending on which way you want the blade to rotate. Make the keyframe on frame 8 CYCLE back to frame 1. Then, make the interpolation on frame 1 LINEAR so you don't get weird slowing down and speeding up. If its too fast or slow, just drag the keyframe on frame 8 along the timeline and see the results. Hope this helps.

Also, don't bother with actions and stuff. Sounds finicky.

basshole · Post by **basshole** » Thu Jun 18, 2009 2:21 pm

Yes, I thought of this. The blades were originally not their own layer, so I'd have to make each one a separate layer for this to work. And they're supposed to spin all the time. . .still shouldn't use an action?

heyvern · Post by **heyvern** » Thu Jun 18, 2009 2:41 pm

I got this to work with a bone and a cycle key frame back to frame 1. "Blade" spins around and around forever. Tried it in both 5.6 and 6. Just do the same thing Mikdog explained. Instead of the layer do this with the bone. I rotated the bone 0 on frame 1. On a later frame rotate the bone 360. Set frame 1 to linear, set the later frame to cycle back to frame 1. Hit play.

http://www.lowrestv.com/anime_studio/fo ... -blade.zip

Using the cycle interpolation the blade will spin for ever. Actions are not really suited for using with continuous repeating motions. They should be used for specific poses or short actions that you need to place at different frames in the animation.

-vern

basshole · Post by **basshole** » Thu Jun 18, 2009 3:17 pm

whoa whoa whoa...theres a 6? should i upgrade? is it the most amazing thing ever? i will try your suggestion. right now the keys default to smooth. maybe thats the problem? if i shouldnt use an action for this then what? just cycle it in the main timeline?

basshole · Post by **basshole** » Fri Jun 19, 2009 1:56 am

Hey I got it! I don't know if it was setting it to 0 on frame 0 or the linear setting for that first key, but it works now.

Regarding actions: if I create one and "insert copy" into the timeline, it just becomes a set of keys as far as the program's concerned, right? No different than if I created the animation from scratch in the main timeline?

basshole · Post by **basshole** » Fri Jun 19, 2009 1:57 am

Hey I got it! I don't know if it was setting it to 0 on frame 0 or the linear setting for that first key, but it works now.

Regarding actions: if I create one and "insert copy" into the timeline, it just becomes a set of keys as far as the program's concerned, right? No different than if I created the animation from scratch in the main timeline?

Okay I lied. It seemed like it was working, then I tried to make it faster. Now it changes direction again, and for some reason, it goes FASTER if I move the cycle key FURTHER from the first frame of animation. If it has to make a full revolution in fewer frames, shouldn't that make it speed up?

It seems to work at certain "speeds" and change direction at others. For instance, if I make it so it takes 18 frames for it to revolve, continues in same direction. 24, it's FASTER, but now switches and goes back the other way at a certain point. 20, slower than 24, but continues in the right direction.

Weirdest thing ever.

toonertime · Post by **toonertime** » Fri Jun 19, 2009 3:29 am

thanks mikdog for the 2 torial on
making something spin around!

I never figured it out until now
because i am a dumb bastard

heyvern · Post by **heyvern** » Fri Jun 19, 2009 3:30 am

Yes, inserting a copy of an action just inserts a copy of the key frames. Like I said, there is absoutely no point to insert an action for this purpose. If you want it to spin for the whole animation than use the cycle. You can even stop the cycle with a new key frame and start it up later. Much easier than using an action

--------------------------------------

The spinning bone is NOT changing direction.

AS doesn't work that way. If a bone is moved in the negative direction that is the direction it moves in. The bones in AS do not rotate based on the shortest distance. The bone won't rotate the other way just because it's closer. It rotates in the direction it was rotated even if it has to go all the way around.

I think what you may be seeing is that the number of frames is so small it only APPEARS to be moving backwards because there aren't enough frames to show the change in angle. Make the keys to close and there aren't enough to split 360 evenly. The bone might go from 10 to 90 in one frame and look like it spun backwards when it actually just jumped all the way around in one frame.

Moving the key AWAY from zero makes it go SLOWER. It has more frames to move the same distance. Moving the key closer to frame 0 makes it go faster. Move it TOO close and you get odd results. You can't go any closer than... 4 frames? You need a minimum of 4 frames. That would be 90 degrees of rotation for each frame. If you do that it may appear to move backwards like an optical illusion. Like wheels spinning that LOOK as if they are going backwards.

In conclusion the "blade" is NOT going backwards in that file no matter how close the key frame is to the start of the loop.

-vern

basshole · Post by **basshole** » Fri Jun 19, 2009 4:09 am

Then it definitely appears backwards in a rendered movie. At any rate, I found 22 frames to be a good speed for a full revolution, and it doesn't appear to change direction.

The reason I wanted the action is so I can set this animation up in multiple shots without having to rig it manually in the timeline each time. This is a thing that will be used every time this saw blade shows up in the short film, not just one shot. It's just a timesaver, a way to insert the keys in fewer keystrokes.

Mikdog · Post by **Mikdog** » Fri Jun 19, 2009 10:11 am

Hmm...

Make sure the cycle's not going back to frame 0, but to frame 1. And make sure you set the rotation for frame 1 to 0 degrees. So make sure there's a keyframe on frame 1.

Then at 22 frames set the rotation to 360 degrees and cycle it back to frame 1.

Then set the interpolation of the keyframe at frame 1 to LINEAR, not smooth.

Otherwise I'd be interested if you posted the file or a movie clip.

I wonder if you're not getting the problem of reality where a wheel spins so fast that it starts looking like its going backwards? But if your interpolation is set to linear this shouldn't be a problem.

Toonertime - that made me laugh. Ha ha. Crazy. Did you just make a haiku?

basshole · Post by **basshole** » Fri Jun 19, 2009 2:21 pm

at 22 it looks right and works fine, so I'm good. As for everything else, I did as you said.