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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.
 
devil20

December 18, 2004, 12:31 AM

Hi
I want to design collision detection my engine but confused about AABB and OOB boxes . I want to add code for collision between two object that might be convax or concave . So first I need to build hierchy structur of object and find intersection of boxs.

So guys Which method is faster ? AABB or OOB ?

And for fast distance computation between two object ? OOB or RSS ?

Any one can suggest good matrial ?

devil20

 
Pogacha

December 18, 2004, 09:13 AM

In intercept detection, AABB is allways faster than OOB, the problem is that you canīt rotate the AABB, so you need to recompute the AABB and this could be expensive, OOB intercept detection is not cheaper but donīt need to recompute and it is a minimun volume container, in other hand, a sphere container instead is situable for this, donīt need to recompute (except the center) and it is cheap.

So:

AABB : Needs to recompute, cheaper intercept detection, medium volume and variable.

OOB : Dont needs to recompute, expensive intercept detection, fits volume and fixed too

Sphere : Dont needs to recompute, cheap intercept detection, big volume and fixed

Convex polyhedra: Needs to recompute, expensive intercept detection, minimal volume for convex objects.

Array of convexs polyhedras: Concaves polyhedras can transformate in an array of convexs polyhedras.

About distance Im not sure what for you need it. Penetration distance ... or?

Bye
Pogacha

 
devil20

December 19, 2004, 10:18 PM

Hi
Thanx for reply
Basically I need nearest distance between two object. And i have two shape for collision one is stationary and other is moving inside first object and it is always growing it's size till it is not fit maximum and collide with first object.
So every frame i need to calculate distance and collision query and i have to make collision model of it So it is very expensive and very memory usage . So how can i handle with that ?

So I need fastest collision between two object and nearest distance between it But fast ... How ? :) Any good method ?




 
Pogacha

December 20, 2004, 04:51 PM

Nearest distance can be calculated doing point to point (n^2) and then point to plane (n^2) (only if the planeīs normal projectated form point to plane
get inside the face owned by the plane), the min of all of them is the nearest.
A BSP will be fine to speed up but Iīm not sure if I correct understand your problem.

 
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