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In almost all 3D games collisions between complex shaped objects must be detected. For collision detection the triangle meshes can be used directly but this is a lot slower than using boxes, spheres or convex shapes. Therefore, for each model a collision model should be created that consists only of simple primitives. This collection of shapes approximates the shape of the detailed 3D graphics model. This blog posts discusses how we can use the XNA content pipeline to load shapes from a collision model created in a 3D modeling tool. The example source code can be downloaded.

In the previous post I have introduced the concept of a Pose. A Pose is a new type defined in DigitalRune Geometry. It defines the position and orientation of an object in 3D space.

In this post I will describe how a Pose can be used to define a World or View transformation matrix…

The task of positioning an object in space is so important in a game that we have introduced a type called Pose in DigitalRune Geometry. A Pose describes a position (a Vector3F) and an orientation (a Matrix33F or a QuaternionF) in 3D space. It is very similar to a transformation matrix…

Here is another Windows Phone 7 physics example: It shows a few bodies and a 3d ragdoll. Tilt or shake the phone to move the bodies.

Video

Download DigitalRune Physics Phone Sample

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Windows Phone 7 is awesome! – This blog post shows DigitalRune Physics on a real Windows Phone 7 in action. The full sample source code can be downloaded at the end of the posting.

Video

Following video shows the sample running on a Samsung Omnia 7 (a great WP7 device!):

Sample Description

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Besides DigitalRune Physics we have been working on DigitalRune Graphics for several month now. I thought it would be nice to use a few graphics effects of DigitalRune Graphics to make our physics demos more interesting. – And here is the result: A short video testing screen space ambient occlusion, an atmospheric scattering skydome and god rays in a simple XNA physics demo. (Implementation details follow after the video.)

Fine, we have found a way to implement Continuous Collision Detection (CCD), but how do we integrate this into our game physics library?

This article explains how to use CCD in game physics; especially a technique called motion clamping that is used in DigitalRune Physics and possible pitfalls you could come across when you use game physics with CCD.

Have you ever heard of Speed Reading? Forget speed reading – let me introduce you to Speed Watching!

But, first a little background information: What is speed reading? From Wikipedia:

Speed reading is a collection of reading methods which attempt to increase rates of reading without greatly reducing comprehension or retention…

The last posts (Continuous Collision Detection – The Problem and Continuous Collision Detection – Solutions) covered Continuous Collision Detection (CCD). Here are a few more notes related to CCD.

Notes

• CCD is more expensive than discrete collision detection.
• Use CCD only for objects that move with a velocity that is high (relative to the object’s extent).
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In the last post we talked about the shortcomings of discrete collision detection and why we need continuous collision detection (CCD). Now it is time to discuss ways to implement CCD to avoid tunneling of objects (missed collisions) and find the time of impact.

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