// TODO - ED: Test
// Source: https://github.com/erich666/GraphicsGems/blob/master/gems/RayBox.c
public bool IntersectRay(FixRay ray, out Fix distance)
{
int whichPlane;
bool inside = true;
Quadrant[] quadrant = new Quadrant[3];
Fix[] maxT = new Fix[3];
Fix[] candidatePlane = new Fix[3];
Fix[] coord = new Fix[3];
FixVec3 intersection;
Fix[] minB = { _min.X, _min.Y, _min.Z };
Fix[] maxB = { _max.X, _max.Y, _max.Z };
Fix[] rayOrigin = { ray.origin.X, ray.origin.Y, ray.origin.Z };
Fix[] rayDirection = { ray.direction.X, ray.direction.Y, ray.direction.Z };
// Find candidate planes; this loop can be avoided if
// rays cast all from the eye(assume perpsective view).
for (int i = 0; i < 3; i++)
{
if (rayOrigin[i] < minB[i])
{
quadrant[i] = Quadrant.LEFT;
candidatePlane[i] = minB[i];
inside = false;
}
else if (rayOrigin[i] > maxB[i])
{
quadrant[i] = Quadrant.RIGHT;
candidatePlane[i] = maxB[i];
inside = false;
}
else
{
quadrant[i] = Quadrant.MIDDLE;
}
}
// Ray origin inside bounding box.
if (inside)
{
distance = Fix.Zero;
return(true);
}
// Calculate T distances to candidate planes.
for (int i = 0; i < 3; i++)
{
if (quadrant[i] != Quadrant.MIDDLE && rayDirection[i] != Fix.Zero)
{
maxT[i] = (candidatePlane[i] - rayOrigin[i]) / rayDirection[i];
}
else
{
maxT[i] = -Fix.One;
}
}
// Get largest of the maxT's for final choice of intersection.
whichPlane = 0;
for (int i = 1; i < 3; i++)
{
if (maxT[whichPlane] < maxT[i])
{
whichPlane = i;
}
}
// Check final candidate actually inside box.
if (maxT[whichPlane] < Fix.Zero)
{
distance = Fix.Zero;
return(false);
}
for (int i = 0; i < 3; i++)
{
if (whichPlane != i)
{
coord[i] = rayOrigin[i] + maxT[whichPlane] * rayDirection[i];
if (coord[i] < minB[i] || coord[i] > maxB[i])
{
distance = Fix.Zero;
return(false);
}
}
else
{
coord[i] = candidatePlane[i];
}
}
intersection = new FixVec3(coord[0], coord[1], coord[2]);
distance = (intersection - ray.origin).GetMagnitude();
return(true);
}
// TODO - ED: Test
public bool IntersectRay(FixRay ray)
{
Fix dummy;
return(IntersectRay(ray, out dummy));
}
