DigitalRune Geometry supports automatic generation of bounding shapes and convex hulls. Using simple bounding shapes or convex hulls is more efficient than using arbitrary triangle meshes in game physics. In this post we will investigate different kinds of bounding shapes.

What's up dude?

Let's look at a practical example. Here is the Dude from the XNA Skinned Model Example:

The model has 13132 vertices and the skeleton has 60 bones.

Bounding Spheres

Here is the same model where a bounding sphere is computed for the vertices of each bone.

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Yet another blog post about character controllers for 3D games, and this time we will talk about the actual implementation.

Kinematic Character Controller Using Discrete Collision Detection

Here is how the character controller in our Character Controller Example works:

Capsule Shape

The character is represented as a an upright capsule that does not rotate:

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There are at least two ways to implement a character controller for a 3D game: Kinematic and Dynamic Character Controllers. In this post we discuss the difference and which solution is better.

A short reminder:
In this context a character controller is the piece of code that computes the movement of the player character in the game. It takes care that the user does not run through walls, can step up/down, jump etc. The character is often modeled as an upright capsule.

Related posts:  3D XNA Character Controller Example and Character Controller Requirements

Kinematic Character Controller

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Here is a list of physics engines. This blog entry will be updated from time to time. If you know other useful links, please let us know and we will include  them in this list.

• 3Impact
  Game engine with dynamics.
• AERO
• AgX Multiphysics Toolkit 
• Animats - Falling Bodies
  Ragdoll physics.
• BEPUphysics
  3D physics engine designed specifically for the XNA Framework
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Here is a list of books related to rigid body dynamics and game physics.

Physics for Game Developers by David M. Bourg This book is an easy-to-read introduction to game physics. It explains the basics (kinematics, kinetics, forces, particles, rigid bodies, collision response) and several applications (projectiles, ships, hovercrafts, cars, etc.). The book is for beginners. You will need other sources for advanced topics, like rigid body contacts or joint-handling. I have encountered several errors while reading the book, so make sure to read the errata on the book's website: http://www.oreilly.com/catalog/physicsgame/

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This is a collection of links about game physics, especially rigid body dynamics, and related topics. 

• 3D World Simulation - Martin Baker
  3D world simulation knowledge base by Martin Baker containing a 3D physics section.
• Brian Beckman’s The Physics of Racing
  The how's, why's and wherefore's of punting a car around a track...
• Classical Mechanics
  Online course.
• Computer Simulations in Physics
  Physics Simulations page by Maciej Matyka. Mainly about soft bodies and fluids.
• Chris Hecker's Rigid Body Dynamics Information
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In 2005 I finished my master thesis about rigid body dynamics. It shows how to build a rigid body physics engine for interactive 3d applications. I am sure it is a good starting point for everyone who wants to learn about game physics.