itsjustme

Not a problem, Rodney. I hope they will help people avoid the numerous mistakes I make...I'm learning quite a bit from them myself.

I'll throw these together as well. Thanks, Robert!

Try flipping your normals...they might be facing inward. Hope that helps.

As much as I don't like doing them, I'll have to use a "stay alive" post for this thread again. This is the busiest time of year for me, so I haven't been able to get much done beyond the first bouncing ball exercises...I learned quite a bit doing those though, thanks to Robert. If I'm lucky, I'll get some time this week to get more things done.

I took a very quick look so far...I didn't see the problem until I set my project to 30 frames per second. The project should be 24 frames per second. See if that clears things up, Rodney. I'm still going to go over it to see if there is any error due to the moving of the "pivot" bone, so there still may be an issue to be dealt with.

The physical CD does exist, but it isn't necessary for running the program...the key functions like the subscription version except it doesn't expire.

I think I know what's going on in there, Rodney...I'll have to look at it tonight to sort it out. The moving of the pivot changes where the source of the squetch comes from, but it also moves the geometry some. I should have looked at the contact frames again to make sure everything was working correctly. Nice catch, Rodney!

Just to tie up the last bouncing ball exercise, I attempted to incorporate Robert's suggestions and get the origin of the squetch more accurate. I started the sequence at about 1/3 from the top of the arc on the initial drop, had the squetch start about 60% from the ground, moved the origin of the squetch to the center of the ball except on the contact frames and added some roll. The "aim at" constraint proved to be inaccurate in some situations (due to how the rig in the ball works), so, I just manually aimed the "pivot" bone using "Onion Skin" set to show where the ball would be on the following frame. Here is a ZIP with the ball, Choreographies, notes and renders. I've done some thinking about the next one...now I can do some more serious planning for it. bouncing_ball_exercises_02_with_notes_update.zip

Very cool!

The turtle is looking great so far!

At AnimationMentor the next assignment would be a ball bouncing off various walls and obstacles. The challenge is to correctly handle bounces and rolls off surfaces that are not horizontal. Also the ball had to jump off the initial surface on its own. That looks cool...I'll give something similar a shot.

It's a modification of a ball model that Robert made several years ago...the direction of squetch being independent of the rotation of the geometry is what I've added.

Very cool! I'll have to figure out the next thing to work on. Thanks for taking a look at these. The rigging on the ball allows the squetch to be independent of the rotation of the ball (although it looks like it contributed to the source of the squetch not being at the contact you mentioned...I'll have to do a little thinking about that). I didn't bother with the ball rotation in this one since the stripe was hidden. Here's a quick video showing the controls. ------------------- EDIT ------------------- I think if I animate the pivot point, it might get rid of the problem with the offset squetch source...I'll mess with that tonight. ball_squetch_controls.mov

Looks great!

I don't really have a great eye for this yet, so I'm still getting used to it. Initially, it felt like the ball hung in the air a little long, but the more I look at ball bounces, the more correct it appears. I added an on/off Pose for the stripe this time. I attempted to add everything suggested, we'll see if I was successful. Here's the next one with included notes, renders, squetch ball and choreographies: bouncing_ball_exercises_02v_with_notes.zip

That might be the best move, Robert. Here is what I got for those along with notes in HTML, renders, squetch ball and Choreographies. bouncing_ball_exercises_01v3_with_notes.zip

I think it works perfectly, John.

That explains it very well, Robert...it clears up some things for me. Thanks for taking the time on this. I'll do some work on this today. If I'm lucky, I'll finish another version and post it.

That was a lot of fun, Nancy!

Okay, I think I get it...this post that Yves made puts it into numbers. I'll fix this tonight.

There's the problem. A ball that falls from half as high does not take half as long to reach the ground. It takes a bit longer. A ball falling from 6 feet takes longer to fall thru the first 3 feet than the second 3 feet, right? Because it was accelerating all the way thru. Consider a ball that falls from 6 feet, bounces up and falls again from 3 feet. The new fall from 3 feet should take as long as the first fall from 6 to 3 feet. Consider that a fall always starts falling from a velocity of zero, no matter how high or not high it has bounced. Hmmm, I'll have to digest that a little. I assumed that on the second bounce (and after) it would also fall 1/4 the distance at 1/2 the height and would have the same curve to the spline as the first bounce. ------------------- EDIT ------------------- I'll let it sink in for a little while and tackle it when I get home.

When I get home this evening I'll see if I can figure out where I went wrong...I'm stumped at the moment (I can't take a look at it where I am).

This is a trick question. If I'm understanding the question, it would be the same rate. That rate is on the chart from animationphysics.com that I linked to in the notes. Yes, it will always take the same time to fall x feet, no matter what height it starts at. Now... how can we use that to inform how long each bounce takes? I made each bounce last half as long because I thought I made each bounce half as high...unless I made a mistake in there somewhere.

This is a trick question. If I'm understanding the question, it would be the same rate. That rate is on the chart from animationphysics.com that I linked to in the notes. Where I possibly went wrong (I think) is that I assumed that using the exact same bias settings on each bounce would produce the same results if everything was scaled equally...that might not be the case. I didn't check it close enough is what I'm thinking.

I'm not sure what you mean, Robert. I used the tutorial (from http://www.animationphysics.com/) that is linked in the notes to figure how fast the ball would fall...did I misunderstand the tutorial or is there something wrong with the tutorial? I used the same rate of fall for each bounce because there was no force other than gravity involved...was that inaccurate? ------------------- EDIT ------------------- Or maybe I just thought I had made it the same rate of fall....I'll have to check later today. I assumed a couple of things, I'm thinking. ------------------- EDIT ------------------- According to the tutorial, it should have been 1/4 of the distance at 1/2 the time...so, if the height was 48 inches (the initial height I used), it would be approximately 36 inches at 6 frames since the ball should take 1/2 second to hit the ground (also according to the tutorial). I adjusted this slightly, so mine was around 37 inches at 6 frames...I explained it in the notes.