Jump to content
  • Advertisement
Sign in to follow this  

Inertia at central mass on a box?

This topic is 4318 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

So I've tried to learn physics :) So I've been reading some articles by Chris Hecker, now I've been reading about angular stuff. And now I want to calculate the inertia of a 2d box at it's central mass, the article says "I^A (Around A, which is CM now) is the sum of squared distances from point A to each other point in the body, and each squared distance is scaled by the mass of each point" Hmm... so I was thinking doing something like using the four points that build up the box. But then in this example by Eric Catto he does:
I = mass * (width.x * width.x + width.y * width.y) / 12.0f;
Can anyone explain why? Thanks /MindWipe

Share this post


Link to post
Share on other sites
Advertisement
With point masses you take the sum to calculate the moment of inertia. For a rectangle, the sum over each point turns into an integral over the body area. If you evaluate this integral it will give the formula from Erin Catto.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

Participate in the game development conversation and more when you create an account on GameDev.net!

Sign me up!