natural leg movement

**VirtualAce** · 01-10-2004

I respect you as a programmer Bubba, but on this one I completely disagree.

I think I'm gonna cry.

Actually you have every right to disagree with me - its just another approach to the same problem.

Don't hate me SilverCoord I'm not talking out of my arse - just a different approach.

**JaWiB** · 01-10-2004

Now with real-time skeletal animation you could cause your character to crumple down against a wall or physically react to his/her environment which would be cool, but most don't. Just shoot someone next to a wall and watch what happens. They normally end up lying down in the same position as their other dead companions with one head or both legs sticking through the wall.

There is a recent game that uses skeletal animation albeit it need a bit of refining since the characters tend to end up in some very...shall we say 'acrobatic'...positions.

Its been called "Ragdoll Physics" and its pretty awesome. If you don't believe me, play Rainbow Six 3 for Xbox (not sure if the computer version incorporates it). You almost never see the same position twice and although its not perfect it leads to some pretty awesome visuals...Oh I think I have a link to a movie:

http://www.greenvsyellow.com/videos.html

Yeah that site is pretty ugly, but the movie was cool

**~~Silvercord~~** · 01-10-2004

hahahaha, don't worry I'm afraid to pick a fight with you because we might stray onto territory where you know more, but on this one I think I've got a pretty good idea of what's going on

EDIT:
yeah, ragdoll physics seems ridiculously difficult to implement

**VirtualAce** · 01-10-2004

Hell no! An animator goes in there and sets the keyframes of joints and when they get to that keyframe, and all you do is interpolate the angles to produce smooth rotations (esp with quaternions if you've implemented them)

LOL! Well then we might be talking about the same thing. Linear interpolating between two known vertexes and angles is quite easy. The two knowns would have to be there as a guide. I could never imagine trying to simulate even one movement w/o some type of pattern or guide to go by.

**~~Silvercord~~** · 01-10-2004

it's not linear interpolating if you are interpolating angles, the bones literally rotate as they would in real life.

**VirtualAce** · 01-10-2004

Yeah the new Rainbow uses it. Thanks for the reminder. I've got so many new and upcoming games I want I forgot the title.

My game magazine stated that sometimes the dudes can end up in some pretty precarious positions but overall it seems to work well.

**~~Silvercord~~** · 01-10-2004

it's watching those rainbow six movies and other things like that which make me feel totally incompetent as a programmer. i'd like to meet whoever programmed that engine...and punch them all in the face

**VirtualAce** · 01-10-2004

Getting me lost on this one. So how do you interpolate an angle with only one known? Interpolating usually requires two known values.

For instance I could linear interpolate between one set of vertexes and another to produce an in-between frame, but it would retain it's overall composition. Morphing is done quite nicely using this.

Oh and I can't believe you said the Q....quaternion word. I've looked at those time and time and time and time again and I've come up with one thing. The people who understand them sure don't know how to explain them so that others can understand them.

**~~Silvercord~~** · 01-10-2004

keep in mind i've only read a lot of theory, I haven't actually implemented this yet. but you do interpolate based on two known values, one is the last keyframe, and the other is the next keyframe. the model file tells you when each keyframe occurs (what point in time since the start of the animation loop).

EDIT:

Oh and I can't believe you said the Q....quaternion word. I've looked at those time and time and time and time again and I've come up with one thing. The people who understand them sure don't know how to explain them so that others can understand them.

calm down buddy, nobody really understands them. I tried to be a nerd and I took my math book out and actually tried reading about them and understanding them at a low level...aint gonna happen. This will be the one thing you copy and use without feeling too bad about

**VirtualAce** · 01-10-2004

There is another program that uses these ragdoll physics. It's called Stair Dismount or Posturrat. The goal of the game is to do as much damage to the dude as possible by pushing him off of a staircase. You can alter x and y angles of force and the magnitudes of these angles -> force of the push to knock him off the stairs. He crumples and reacts to the stairs and environment quite nicely. He is merely composed of several spheres but the overall effect is quite convincing.

There is another one called Truck Dismount - look them up on www.google.com and you will see an example of ragdoll physics. This is something I would love to try. I also have d/l some interesting angular momentum physics and demos w/source - you can throw blocks around in a room and they bounce off the walls correctly in all dimensions - including angular and rotational velocities. Very cool.

**DavidP** · 01-10-2004

well here is what I have to work with.

All of my 3d models I have downloaded from www.battletech-movie.com, since they had perfect looking models for what I wanted to achieve.

They are all .3ds format, and so usually if I feel like opening them up I just open them up in 3ds Max and take a look at them.

As far as I know the files contain only the models, being composed of about 50 meshes each. They do not contain any pre-rendered animation or skeletal frames.

I have been simply loading the models into memory and working with each mesh so far.

EDIT:

if i want to i CAN enter 3ds Max and begin doing keyframe several keyframe animations. I don't have a whole lot of experience with them, but I have done some animations before, and I could do them in 3ds max if I had to.

I have never made a skeletal frame in 3ds max before. that would be new to try.

**VirtualAce** · 01-10-2004

I guess you will have to interpolate between two meshes then.

**MrWizard** · 01-10-2004

Sure I would be happy to help. I don't know how much help I'll be though. For our project we used x files for animation and models with DirectX API calls. However, one of my classes last semester we had to do it all in software so I am aware of how it is accomplished. I chose the MD5 Format ( Doom3's model format ) for my skeletal animation project. Just PM me or post here if you need help.