Hi All,
I want to do an animation that involves an item ( or several items) ( a ball for example) resting on a suspended rope, perhaps bouncing off a rope or rolling along a rope at some point. I'm guessing that a trampoline effect might require similar techniques to what my problem does.
Can anyone point me to any good tutorials where I can get the basics for something like this? I have done some rudimentary animation where I have plunged ahead to try to do something, later finding an easier way via online tutorials or the manual and thinking "Gee, I wish I'd known that when..." This time I would like to "read the manual" in order to save a lot of the trial and error, time and headaches. Thanks for any guidance you can offer.
-Patrick
ball on a rope, yo-yo etc. and physics
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I think the best is to do it by hand. You only have to understand the logic of moving ropes.
Here you have a tutorial:
viewtopic.php?t=15647
Take in count every move first have a resistance, then a consequence. So you must animate it dephased: while closer to the rope tip, later will be the movement.
Here you have a tutorial:
viewtopic.php?t=15647
Take in count every move first have a resistance, then a consequence. So you must animate it dephased: while closer to the rope tip, later will be the movement.
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Rigged animation supervisor in My father's dragon - Lead Moho artist in Wolfwalkers - Cartoon Saloon - My personal Youtube Channel
Construction curves and point animation.
Construction:
Have a look at this animated GIF:
The two moving black lines are your lose rope. The path they describe is an ellipse, and it's the path of any item on the rope rolling around. You just need to move the two points outside the ellipse to get a path for a shorter rope with more tension. So all you need is to draw an ellipse and place it so it fits your imagination.
Animation: your ball, and two lines with just 2 points. Animate the ball first, let if follow the path. Have the 2 lines meet under the ball, select the 2 points, animate it so it's always under the ball. Done.
Construction:
Have a look at this animated GIF:
The two moving black lines are your lose rope. The path they describe is an ellipse, and it's the path of any item on the rope rolling around. You just need to move the two points outside the ellipse to get a path for a shorter rope with more tension. So all you need is to draw an ellipse and place it so it fits your imagination.
Animation: your ball, and two lines with just 2 points. Animate the ball first, let if follow the path. Have the 2 lines meet under the ball, select the 2 points, animate it so it's always under the ball. Done.
As Imago suggested, You could use physics and a rig, but I agree with selgin and slowtiger here, it is best to animate these by hand.
Here is a rope I animated not long ago with bones dynamics.
http://www.youtube.com/watch?v=iPxxsdIq46I
Here is a rope I animated not long ago with bones dynamics.
http://www.youtube.com/watch?v=iPxxsdIq46I
Just for fun I built that setup. 15 minutes.
http://www.slowtiger.de/examples/seil.mov
.anme file:
http://www.slowtiger.de/examples/seil.anme.zip (v5.6)
It's also an example of "how to make a non-circular pendulum".
http://www.slowtiger.de/examples/seil.mov
.anme file:
http://www.slowtiger.de/examples/seil.anme.zip (v5.6)
It's also an example of "how to make a non-circular pendulum".
Slowtiger's example is visually nice but wrongly physically. The length of the rope decreases when the ball roll over it which is strange. The construction should be this:
Say that the distance between the fixing points is R.
1) Draw a Catenarybetween the fixing points. Calculate its length. L
2) With that given length, calculate the solution to the following equation:
a^2 + R^2 = b^2 (this is the position of the ball touching the wall)
a + b = L (this is by definition the length of the rope)
a and b are the distance from the position of the ball to the link points.
3) Obtained a and b draw the ellipse with its focuses at the link points and the mayor and minor axis to be b and a respectively.
This way, the rope and ball effect will be mathematically and physically correct.
-G
Say that the distance between the fixing points is R.
1) Draw a Catenarybetween the fixing points. Calculate its length. L
2) With that given length, calculate the solution to the following equation:
a^2 + R^2 = b^2 (this is the position of the ball touching the wall)
a + b = L (this is by definition the length of the rope)
a and b are the distance from the position of the ball to the link points.
3) Obtained a and b draw the ellipse with its focuses at the link points and the mayor and minor axis to be b and a respectively.
This way, the rope and ball effect will be mathematically and physically correct.
-G
lol... 
Sometimes it is needed to understand how the real world works to make good cartoons. If the physics rules (real or fiction) of your cartoon aren't consistent along all the animation you can confuse the audience with unexpected behaviour.
It is a usual kind of joke to force the physics laws in comic cartoons, to make possible, the impossible. But if the animation doesn't use that kind of jokes on the precise moment and timing, a bad usage of illogic physics ruins the animation.
Those are the right equations, for anyone who want to use it.
Anyway, I still thinking that the rope acts weirdly, but anyone can make animation with its own physics, there won't be a space-time hole or similar doing that
:
-G
It is a usual kind of joke to force the physics laws in comic cartoons, to make possible, the impossible. But if the animation doesn't use that kind of jokes on the precise moment and timing, a bad usage of illogic physics ruins the animation.
Those are the right equations, for anyone who want to use it.
Anyway, I still thinking that the rope acts weirdly, but anyone can make animation with its own physics, there won't be a space-time hole or similar doing that
:-G
Thanks for the tips, going forward now.
Thanks to all for the suggestions. I have finally got the the point in the animation where I need to do this and hadn't realized until now that I had more responses on the thread. My curve/dip is going to be so minute that Slowtiger's solution should do the trick. Thanks also Genete, for the mathematical solution, I'll definitely be looking that over just to get a better grip on the physics of it all. I also took the "Just draw it out" suggestion for a close up shot where the rope isn't in the frame. I appreciate all the good help.
Thanks to Selgin too. Nice tutorials.
Selgin, Thanks also for the great tutorials. I watched the rubber arm one from one of your other posts which I really enjoyed. The one with the dinosaur tail will certain come in handy later. I had just done a tail a little while back. Sure wish I had seen that one before I started! Regards -Patrickselgin wrote:I think the best is to do it by hand. You only have to understand the logic of moving ropes.
Here you have a tutorial:
viewtopic.php?t=15647
Take in count every move first have a resistance, then a consequence. So you must animate it dephased: while closer to the rope tip, later will be the movement.