Technical Art for Games » 3D Animation

Biped Editor for Unity 3.0

Adam — Wed, 14 Jul 2010 02:27:33 +0000

I’ve been really head-down for awhile with work, the latest of which has involved some pretty substantial refactoring of Touch KO for a big update this summer (finally!). Since I’ve been working in Unity 3.0, I thought I’d share a short clip of a tool I developed during the refactoring process. It’s a biped component along with an editor for interactively adjusting collision shapes and sizes as well as joint limits. The component also has functionality to perform an automatic mass distribution based on human values, as well as interfaces for entering and exiting ragdoll. If I manage to get caught up on things after the update I’ll probably share the code on here eventually, but as anyone who follows the site may have guessed it’s been really busy lately O_o.

Note: for best viewing, I recommend turning the resolution on the video up to 1080p and watching full-screen, since that’s my native resolution and it will be easier to read some of the buttons.

Root Motion Computer for Unity

Adam — Wed, 26 May 2010 16:45:22 +0000

I recently finished up a new component for Unity as part of a contract job with Mixamo. For those of you who are unaware, Mixamo provides an online motion capture download and retargeting service powered by HumanIK. It lets you use sliders to creatively adjust a piece of motion capture data and then automatically retarget it onto your own hierarchy and download it for use in your game. It’s really slick and pretty affordable, so it’s definitely worth checking out, particularly for any indie developers out there.

At any rate, the component that I created is designed to let animation data, rather than procedural velocity values, drive a character’s motion in space. The component sits on top of Unity’s animation API to let you simply play, crossfade, and blend animations using any of the existing API methods, and the computer takes care of everything else after the fact. The way it works is by tracking the position and rotation of the pelvis in the space of the character’s root node for each active AnimationState and then backward applying this motion to the root node itself and snapping the pelvis back into its position hovering over the root. Since the source code is all available in the project, I won’t belabor the details too much here, but you can certainly ask me if you have any questions. (The one thing perhaps worth mentioning, as an addendum to the video, is that the pelvis forward axis is not strictly necessary for computing output: only for displaying debug information. For computation, the character’s rotation is determined using the pelvis right axis.)

You can download an example project from Mixamo that contains the component as well as a sample character with some animations. Because the tutorial video on the Mixamo website is compressed pretty substantially, I have also uploaded a copy to my Vimeo account in case you would like to watch it in full HD resolution.

Adding Unity Tools

Adam — Fri, 19 Feb 2010 20:34:40 +0000

Waiting on videos to render is the perfect time to add and update site content, because everything else is bogged down. In that respect, I wanted to note that my Unity tools page is now open for business, where I will be posting more components and editor scripts in the future. For starters, I have uploaded two basic components (each zip file contains a UnityScript and a C# version).

The first component is an aim constraint, to simply mimic the behavior of Maya’s aim constraint. The benefit of using this over a simple call to Quaternion.LookRotation() is that you can specify arbitrary forward and up axes on the constrained object (just as in Maya). You could use this with the AssetPostprocessor class to automatically import constraints in your asset files (FBX, Maya, etc.).

The second component is a look rotation constraint. It allows you to not only specify arbitrary forward and up axes on the constrained object, but also constrain it to a world forward-vector and world up-vector (so it does not need to aim at a target, but can mimic the “pointing” direction of another transform).

New Video Tutorial

Adam — Mon, 19 Jan 2009 15:26:12 +0000

I have completed my second rigging video tutorial. This one focuses on how to rig a twist structure in a forearm that is easily portable into game code, does not interfere with IK, and is not affected by Gimbal locking on the hand.

Hip Constraint and Shoulder Constraint Update

Adam — Sun, 18 Jan 2009 16:38:45 +0000

Following in my pattern of frequent updates, I uploaded more revisions this morning to both the shoulder constraint and hip constraint.

The revision, which is the same in both, is another exception to handle a possible singularity. I never actually had it happen to me in practice, but I realized it was possible when I stopped to think about it. Enjoy!