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[Solved]Need help for collision detection in cubic world


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#1 Wartime   Members   -  Reputation: 103

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Posted 26 April 2012 - 01:40 PM

Hi there,

As you can see here http://www.gamedev.n...for-a-strategy/
I'm programming a minecraft-like game.

A lot of things are done. The only thing I need help with is to make a collision detection.

At the moment the game allows flying around with a first person camera and i want to detect which block and which side of a block a user is facing.

Have you got any ideas to realizing this?

If you need some code of our game please ask.
You can get the whole if you want.

Attached File  Kubos.rar   688.41KB   40 downloads

Thanks for help

Sponsor:

#2 kauna   Crossbones+   -  Reputation: 2337

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Posted 27 April 2012 - 12:30 AM

You can start by a simple collision detection scheme such as detecting if a sphere (camera + some radius) is inside an axis aligned box. The idea is to keep a point with radius outside of an axis aligned box.

I assume that your data structures allow you to easily find the nearest cubes to the camera.

So for each box in the radius you'll check if the sphere is intersecting the box. If so, move the sphere along the normal of the intersecting box surface so that the sphere is outside of the box.

The idea above works for planes, but it doesn't probably handle the corner cases.

Of course, using physics API such as bullet could work here too, but at the beginning it may be over kill.

Best regards!

#3 Krohm   Crossbones+   -  Reputation: 3047

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Posted 28 April 2012 - 01:15 AM

Of course, using physics API such as bullet could work here too, but at the beginning it may be over kill.

That's for sure. Cube-based, axis aligned worlds are pretty in vogue nowadays but bullet has no way to exploit this very strong property. The result might be suboptimal. Overall, I'd still consider physics APIs anyway.

#4 kauna   Crossbones+   -  Reputation: 2337

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Posted 28 April 2012 - 02:51 AM

That's for sure. Cube-based, axis aligned worlds are pretty in vogue nowadays but bullet has no way to exploit this very strong property. The result might be suboptimal. Overall, I'd still consider physics APIs anyway.


Time to learn Bullet (or another physics API) may take few hours more than to code a simple box-sphere collision check, but at the end you'll have access to lots of features (which you can't code in the same time).

For the performance part, it would be an interesting to see how many percents faster a home-grown solution would be. If I had to take a guess, the difference between solutions would be in few percents ranges (either way).

Best regards!

Edited by kauna, 28 April 2012 - 02:52 AM.


#5 Wartime   Members   -  Reputation: 103

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Posted 28 April 2012 - 05:44 AM

Hi,

Thank you for help. Sry for answering so late, I attened a funeral today.

I will try Bullet (I used it for another game and it was really good) again.
Otherwise I try another solution i found out yesterday:

Get all blocks you are sorrunded with a distance of three blocks. Do a d3dxboundingboxtest. All boxes that collide with the ray, do a d3dxintersecttri test.
So i know which surface my ray is intersecting.

This could work too.

Edited by Wartime, 28 April 2012 - 05:45 AM.


#6 Wartime   Members   -  Reputation: 103

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Posted 30 April 2012 - 08:36 AM

My second version is working...




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