Orbiting Planets Animation

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Orbiting Planets Animation // TS6 and Older

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Post by westly // Oct 22, 2006, 4:40pm

Total Posts: 12
I'm having a problem. I could animate a planet in tS 3.x and 4.x to rotate and set to local and then animate it in orbit. I can't seem to get this to work in tS 6.6

I can't find a tutorial on animating planets in orbit around each other with them spinning 360deg like a normal planet would. I've searched the forums also with no luck yet.

Any help is appreciated.

Post by Tiles // Oct 23, 2006, 1:14am

Total Posts: 1037
Should work like in TS 4. What exactly is your problem?

Post by GraySho // Oct 23, 2006, 4:52am

Total Posts: 695
I guess the problem are rotation angles greater than 180. I ran into the same problem once, and could not find an easy solution. Just open the object info box and rotate an object around it's axis, you'll see that rotation goes up to 180, and then turns into -179 and increments towards 0 if you turn it further. Now, if you keyframe that, you get weired results. Add a cube to the scene, record rotation at keyframe 0. Advance to keyframe 30 and turn the cube like 350° and hit record button again. Play the animation and tell me if you see what you expected (or wanted) :rolleyes

Post by Bobbins // Oct 23, 2006, 6:05am

Total Posts: 506
I'll verify this later when I have tS open in front of me but.....

tS considers 350 degrees as a rotation of -10 degrees because translating an object through 350 degrees of rotation gives an identical end result to translating an object through -10 degrees of rotation. It then takes the shortest path between two places - in this case the rotation values. This means that if you keyframe rotations at 0, 30 and 350 degrees:

- tS rotates forwards from 0 to 30 degrees.

- tS then rotates backwards from 30 to -10 degrees (350 degrees) because 30 to -10 is only 40 degrees of rotation. That's shorter than going from 30 to 350 degrees which would be 320 degrees of rotation hence what you see isn't what you might have expected.

You can get corner cases by keyframing 0, 180 and 360 degrees - is it quicker to go from 180 back to 0 or from 180 forward to 360 (which is the same as 0 degrees)? To get smooth rotation then unambiguous paths are needed, so keyframes at 0, 120, 240 (or -120) and 360 (or 0) degrees of rotation will always work as expected because there is a definite shortest path between one keyframe and the next at all times.

Post by Chester Desmond // Oct 23, 2006, 6:25am

Chester Desmond
Total Posts: 323
I could animate a planet in tS 3.x and 4.x to rotate and set to local and then animate it in orbit.

You could try using clips for this.. one for the roataion, and one for the orbit. I haven;t messed with clips much yet, but when first trying them I remember thinking "Hey this is just like "make action local" in older versions.

Post by GraySho // Oct 23, 2006, 6:48am

Total Posts: 695
This is exactly how it behaves bobbins. Still, I think there should be a better way of doing that sort of animation (which is quite simple). Obviously this has been adressed in tS7.

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