Thread: Comparing Matrices (D3D9)

hey, just a stupid question, im new to D3D, previously just ben coding 2D games using Dx7 and the GDI but i decided id make the change to 3D, im reading through a D3D book and im at the part of handling transformations and translations allowing roatation and movement of primitives using matrices. now logicaly i thought, hey if matrices hold position data then surely comparing matrices could tell me if two primitives are coliding or not, so i skimmed the book looking to see if it had any info on collision and to my annoyance not a thing on collision detection in the whole book..
can any 1 point me in the right direction?
thanx

Collision detection actually has nothing at all to do with matrices in regards to meshes. All you do is make bounding spheres/boxes around the meshes you want to check and use a simple geometry formula to calculate if the spheres or boxes collide. Here's a basic sphere collision detection function written in C++:

Code:

BOOL CheckSphereCollision( float XCenter1, float YCenter1, float ZCenter1, float Radius1,
                                              float XCenter2, float YCenter2, float ZCenter2, float Radius2 )
{
    float XDifference, YDifference, ZDifference, Distance;

    XDifference  =  (float)fabs(XCenter2 - XCenter1);
    YDifference  =  (float)fabs(YCenter2 - YCenter1);
    ZDifference  =  (float)fabs(ZCenter2 - ZCenter1);

    Distance  =  (float)sqrt(XDifference*XDifference+YDifference*YDifference+ZDifference*ZDifference);

    if( Distance <=  (Radius1+Radius2))
        return TRUE;  //  INTERSECTION HAPPENED

    return FALSE;  // NO INTERSECTION
}

Conclusion: Google.com is packed and packed full of information about everything. Use it to your advantage.

wow didnt think it'd be as simple, and i guess for some more complex objects u can use multiple spheres / boxes and do a collision check for each one, btw that code u posted is interesting, im used to doing inequality checks (with 2D) without mathematical computation so my collision sub in 2D is normaly more hectic than that, thanks it helped alot