obb

struct ST_OBB // OBB구조체
{
     D3DXVECTOR3 vCenterPos; // 상자 중앙의 좌표
     D3DXVECTOR3 vAxisDir[3]; //상자에 평행한 세 축의 단위벡터
     float  fAxisLen[3]; // 상자의 평행한 세 축의 길이 fAxisLen[n]은 vAxisDir[n]에 각각 대응한다.
};

 

 

 // ST_OBB 구조체 두개의 포인터를 각각 인자로 받아, 두 OBB의 충돌 여부를 체크하는 함수

// 충돌 시 TRUE리턴, 충돌하지 않으면 FALSE 리턴

BOOL CheckOBBCollision( ST_OBB* Box1, ST_OBB* Box2 )
{
     double c[3][3];
     double absC[3][3];
     double d[3];

     double r0, r1, r;
     int i;

     const double cutoff = 0.999999;
     bool existsParallelPair = false;

     D3DXVECTOR3 diff = Box1->vCenterPos - Box2->vCenterPos;

 

     for( i = 0 ; i < 3 ; ++i )
     {
          c[0][i] = D3DXVec3Dot( &Box1->vAxisDir[0], &Box2->vAxisDir[i] );
          absC[0][i] = abs( c[0][i] );
          if( absC[0][i] > cutoff )
               existsParallelPair = true;
     }
     d[0] = D3DXVec3Dot( &diff, &Box1->vAxisDir[0] );
     r = abs( d[0] );
     r0 = Box1->fAxisLen[0];
     r1 = Box2->fAxisLen[0] * absC[0][0] + Box2->fAxisLen[1] * absC[0][1] + Box2->fAxisLen[2] * absC[0][2];

     if( r > r0 + r1 )
          return FALSE;

 

     for( i = 0 ; i < 3 ; ++i )
     {
          c[1][i] = D3DXVec3Dot( &Box1->vAxisDir[1], &Box2->vAxisDir[i] );
          absC[1][i] = abs( c[1][i] );
          if( absC[1][i] > cutoff )
               existsParallelPair = true;
     }
     d[1] = D3DXVec3Dot( &diff, &Box1->vAxisDir[1] );
     r = abs( d[1] );
     r0 = Box1->fAxisLen[1];
     r1 = Box2->fAxisLen[0] * absC[1][0] + Box2->fAxisLen[1] * absC[1][1] + Box2->fAxisLen[2] * absC[1][2];

     if( r > r0 + r1 )
          return FALSE;

 

     for( i = 0 ; i < 3 ; ++i )
     {
          c[2][i] = D3DXVec3Dot( &Box1->vAxisDir[2], &Box2->vAxisDir[i] );
          absC[2][i] = abs( c[2][i] );
          if( absC[2][i] > cutoff )
               existsParallelPair = true;
     }
     d[2] = D3DXVec3Dot( &diff, &Box1->vAxisDir[2] );
     r = abs( d[2] );
     r0 = Box1->fAxisLen[2];
     r1 = Box2->fAxisLen[0] * absC[2][0] + Box2->fAxisLen[1] * absC[2][1] + Box2->fAxisLen[2] * absC[2][2];

     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( D3DXVec3Dot( &diff, &Box2->vAxisDir[0] ) );
     r0 = Box1->fAxisLen[0] * absC[0][0] + Box1->fAxisLen[1] * absC[1][0] + Box1->fAxisLen[2] * absC[2][0];
     r1 = Box2->fAxisLen[0];

     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( D3DXVec3Dot( &diff, &Box2->vAxisDir[1] ) );
     r0 = Box1->fAxisLen[0] * absC[0][1] + Box1->fAxisLen[1] * absC[1][1] + Box1->fAxisLen[2] * absC[2][1];
     r1 = Box2->fAxisLen[1];

     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( D3DXVec3Dot( &diff, &Box2->vAxisDir[2] ) );
     r0 = Box1->fAxisLen[0] * absC[0][2] + Box1->fAxisLen[1] * absC[1][2] + Box1->fAxisLen[2] * absC[2][2];
     r1 = Box2->fAxisLen[2];

     if( r > r0 + r1 )
          return FALSE;

 

     if( existsParallelPair == true )
          return TRUE;

 

     r = abs( d[2]*c[1][0] - d[1]*c[2][0] );
     r0 = Box1->fAxisLen[1] * absC[2][0] + Box1->fAxisLen[2] * absC[1][0];
     r1 = Box2->fAxisLen[1] * absC[0][2] + Box2->fAxisLen[2] * absC[0][1];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[2]*c[1][1] - d[1]*c[2][1] );
     r0 = Box1->fAxisLen[1] * absC[2][1] + Box1->fAxisLen[2] * absC[1][1];
     r1 = Box2->fAxisLen[0] * absC[0][2] + Box2->fAxisLen[2] * absC[0][0];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[2]*c[1][2] - d[1]*c[2][2] );
     r0 = Box1->fAxisLen[1] * absC[2][2] + Box1->fAxisLen[2] * absC[1][2];
     r1 = Box2->fAxisLen[0] * absC[0][1] + Box2->fAxisLen[1] * absC[0][0];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[0]*c[2][0] - d[2]*c[0][0] );
     r0 = Box1->fAxisLen[0] * absC[2][0] + Box1->fAxisLen[2] * absC[0][0];
     r1 = Box2->fAxisLen[1] * absC[1][2] + Box2->fAxisLen[2] * absC[1][1];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[0]*c[2][1] - d[2]*c[0][1] );
     r0 = Box1->fAxisLen[0] * absC[2][1] + Box1->fAxisLen[2] * absC[0][1];
     r1 = Box2->fAxisLen[0] * absC[1][2] + Box2->fAxisLen[2] * absC[1][0];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[0]*c[2][2] - d[2]*c[0][2] );
     r0 = Box1->fAxisLen[0] * absC[2][2] + Box1->fAxisLen[2] * absC[0][2];
     r1 = Box2->fAxisLen[0] * absC[1][1] + Box2->fAxisLen[1] * absC[1][0];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[1]*c[0][0] - d[0]*c[1][0] );
     r0 = Box1->fAxisLen[0] * absC[1][0] + Box1->fAxisLen[1] * absC[0][0];
     r1 = Box2->fAxisLen[1] * absC[2][2] + Box2->fAxisLen[2] * absC[2][1];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[1]*c[0][1] - d[0]*c[1][1] );
     r0 = Box1->fAxisLen[0] * absC[1][1] + Box1->fAxisLen[1] * absC[0][1];
     r1 = Box2->fAxisLen[0] * absC[2][2] + Box2->fAxisLen[2] * absC[2][0];
     if( r > r0 + r1 )
          return FALSE;

 

     r = abs( d[1]*c[0][2] - d[0]*c[1][2] );
     r0 = Box1->fAxisLen[0] * absC[1][2] + Box1->fAxisLen[1] * absC[0][2];
     r1 = Box2->fAxisLen[0] * absC[2][1] + Box2->fAxisLen[1] * absC[2][0];
     if( r > r0 + r1 )
          return FALSE;

 

     return TRUE;
}