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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.

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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Collision detection in 3d games detects whether objects are intersecting. The normal discrete collision detection does so by checking the objects at their current position. Then the game moves the objects and the collision detection checks the objects at their new positions.

This method works for slow moving objects, but for fast moving objects critical collisions can be missed. To detect all collisions we need “Continuous Collision Detection” (CCD), which we will discuss in this and the next blog posts.

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