bool AABB::intersects( const Ray& ray, Vector& pt )
{
// Rays starting and ending in an octree node must be considered
// to hit the node.
// if the start point OR the end point is in the AABB, then it's a hit.
if( containsIn( ray.startPos ) || containsIn( ray.getEndPoint() ) )
{
//generateDebugLines( Vector(0,1,0) ) ;//green is RAY STARTED INSIDE
return true ;
}
Vector tmins, tmaxes ;
// These are red in the profiler.
tmins = (min - ray.startPos) / ray.direction ;
tmaxes = (max - ray.startPos) / ray.direction ;
Vector* sols[2] = { &tmins, &tmaxes } ;
int solS=0, solI=0 ;
real smallestT = HUGE ; // smallest valid t ("so far"). put at inf so first time everything smaller than it.
Vector closestRaypoint ; // smallest rayPoint (associated with "smallest t so far")
for( int s = 0 ; s < 2 ; s++ )
{
Vector& candSols = *sols[s] ;
// i walks xyz
for( int i = 0 ; i < 3 ; i++ )
{
real& t = candSols.e[i] ; // candidate t
// validity: 0 <= t <= length
if( BetweenIn( t, 0, ray.length ) )
{
Vector raypoint = ray.at( t ) ;
// AND ON FACE
// o1 and o2 are the indices of the OTHER faces,
// if i==0, o1=1, o2=2
int o1 = ( i + 1 ) % 3 ; // if( i==0 ) o1=1, o2=2;
int o2 = ( i + 2 ) % 3 ; // else if( i == 1) o1=2, o2=0;
if( InRect( raypoint.e[ o1 ],raypoint.e[ o2 ],
min.e[o1], min.e[o2],
max.e[o1], max.e[o2] ) )
{
// this one wins, if it's smallest so far
if( t < smallestT )
{
smallestT = t ;
closestRaypoint = raypoint ;
// record what face it was
solS = s ;
solI = i ;
}
}
}
}
}
// now here, it's possible smallestT was unassigned,
// which means it'll still be HUGE
if( smallestT == HUGE )
{
// no solution
///generateDebugLines( Vector(.2,.2,.2) ) ;//total miss
return false ;
}
else
{
// there was an intersection.
///generateDebugLines( Vector(1,0,0) ) ;//red means it was a hit
pt = closestRaypoint ;
return true ;
}
}
bool AABB::intersects( const Ray& ray )
{
// VERY IMPORTANT CHECK: If the ray starts inside
// the box, then it's a hit. This was important for octrees.
if( containsIn( ray.startPos ) || containsIn( ray.getEndPoint() ) )
return true ;
#define TECH 0
#if TECH==0
// the algorithm says, find 3 t's,
Vector t ;
// LARGEST t is the only only we need to test if it's on the face.
for( int i = 0 ; i < 3 ; i++ )
{
if( ray.direction.e[i] > 0 ) // CULL BACK FACE
t.e[i] = ( min.e[i] - ray.startPos.e[i] ) / ray.direction.e[i] ;
else
t.e[i] = ( max.e[i] - ray.startPos.e[i] ) / ray.direction.e[i] ;
}
int mi = t.maxIndex() ;
if( BetweenIn( t.e[mi], 0, ray.length ) )
{
Vector pt = ray.at( t.e[mi] ) ;
// check it's in the box in other 2 dimensions
int o1 = ( mi + 1 ) % 3 ; // i=0: o1=1, o2=2, i=1: o1=2,o2=0 etc.
int o2 = ( mi + 2 ) % 3 ;
return BetweenIn( pt.e[o1], min.e[o1], max.e[o1] ) &&
BetweenIn( pt.e[o2], min.e[o2], max.e[o2] ) ;
}
return false ;
#elif TECH==1
// This culls the back faces first, and gives you the answer with the largest valid t
for( int i = 0 ; i < 3 ; i++ )
{
int o1 = ( i + 1 ) % 3 ; // i=0: o1=1, o2=2, i=1: o1=2,o2=0 etc.
int o2 = ( i + 2 ) % 3 ;
// min.x (NX) is possible, PX won't be hit. (unless you're inside the box.)
if( ray.direction.e[i] > 0 ) // CULL BACK FACE
{
real t = ( min.e[i] - ray.startPos.e[i] ) / ray.direction.e[i] ;
// 1. CHECK VALID T
if( BetweenIn( t, 0, ray.length ) )
{
// 2. CHECK IN BOX
Vector pt = ray.at( t ) ;
if( BetweenIn( pt.e[o1], min.e[o1], max.e[o1] ) && BetweenIn( pt.e[o2], min.e[o2], max.e[o2] ) )
return true ; // it's valid in the box
}
}
else if( ray.direction.e[i] < 0 ) // max.x (PX) is possible
{
real t = ( max.e[i] - ray.startPos.e[i] ) / ray.direction.e[i] ;
if( BetweenIn( t, 0, ray.length ) ) // valid t
{
Vector pt = ray.at( t ) ;
if( BetweenIn( pt.e[o1], min.e[o1], max.e[o1] ) && BetweenIn( pt.e[o2], min.e[o2], max.e[o2] ) )
return true ; // it's valid in the box
}
}
}
return false ; // no hit.
#elif TECH==2
// This solves ALL 6 solutions and finds the shortest t.
// Rays starting and ending in an octree node must be considered
// to hit the node.
// if the start point OR the end point is in the AABB, then it's a hit.
// These are red in the profiler.
Vector tmins = (min - ray.startPos) / ray.direction ;
Vector tmaxes = (max - ray.startPos) / ray.direction ;
Vector* sols[2] = { &tmins, &tmaxes } ;
for( int s = 0 ; s < 2 ; s++ )
{
Vector& candSols = *sols[s] ;
// i walks xyz
for( int i = 0 ; i < 3 ; i++ )
{
real& t = candSols.e[i] ; // candidate t
// validity: 0 <= t <= length
if( BetweenIn( t, 0, ray.length ) )
{
Vector raypoint = ray.at( t ) ;
// AND ON FACE
// o1 and o2 are the indices of the OTHER faces,
// if i==0, o1=1, o2=2
int o1 = ( i + 1 ) % 3 ; // if( i==0 ) o1=1, o2=2;
int o2 = ( i + 2 ) % 3 ; // else if( i == 1) o1=2, o2=0;
if( InRect( raypoint.e[ o1 ],raypoint.e[ o2 ],
min.e[o1], min.e[o2],
max.e[o1], max.e[o2] ) )
{
// the box got hit, any side
return true ;
}
}
}
}
// No hit
return false ;
#endif
}
