duncan,

hey, luke here, the force the ground exerts on the guy is actually the SPRING force man. The spring pushes on the guy, but it would fly through to china if the ground didn't push back on it. don't worry about the ground normal force, its actually the spring force.

sorry I haven't helped lately, my wife & I just moved into our first house this week. I should be back in action soon.

quick refresher:

The AP is right, use force to calculate change in A,V, & P

Until now, only 3 "forces" acting on the guy are gravity, spring (if touching ground) & his change in center of gravity (at all times).

You can of course add in dampening forces, which I thoguht we'd figure out later once everything else was working ok. The damping force can be applied in 2 ways... 1 is the air resistance... which should be applied according to the wind's net vector (take into account the wind velocity vector & the guy's velocity vector), & another would be heat loss in the spring, which is actually a friction force applied opposite the springs motion.

anyways... thats pretty simple when you think about it, 5 total forces : gravity, spring, friction, change in center of gravity, wind

Of course you will tweak the values of each until you get the desired behaviour :) & of course there are other tricky forces we can add in, but sooner or later you have to make assumptions with a physics model & count certain things out because they are negligible.

Luke

First off, congratulations to you and your wife! Making room for three? Thanks so much for everything you've helped me with. I tried the "Rate this user" link Gamedev.net just added, but your "user rating" didn't go up. I can't tell you how much you've helped. Thank you so much! I'm going to get start working on it again when I get back, I'm going to Galveston for a few days so I should be refreshed when I get back. Thank you again!

I've dealt with some of the issues, and I now have another question. My simulation seems to run well, except the guy keeps jumping higher and higher, but sometimes returns to an "average" bounce. It is modeled so that collisions are perfectly elastic yet the outcome isn't true to this. Is this due to my calculations? Should I try another method of evaluating?

Hey Duncan,

I'll have to see the code to be any more help. Go ahead & email me & maybe we can start a personal dialog that way...

fyi - luke_miklos@yahoo.com

I bet its just a simple overlooked programming error. However... I can imagine something like this might happen if you don't perform enough physic's model computation iterations each frame. Perhaps? otherwise... I have no clue, I'd have to see code.

Luke