/// <summary>Returns the squared distance from 'point' to 'bbox'</summary>
public static float DistanceSq(v4 point, BBox bbox)
{
float dist_sq = 0.0f;
v4 lower = bbox.Lower();
v4 upper = bbox.Upper();
if (point.x < lower.x)
{
dist_sq += Math_.Sqr(lower.x - point.x);
}
else if (point.x > upper.x)
{
dist_sq += Math_.Sqr(point.x - upper.x);
}
if (point.y < lower.y)
{
dist_sq += Math_.Sqr(lower.y - point.y);
}
else if (point.y > upper.y)
{
dist_sq += Math_.Sqr(point.y - upper.y);
}
if (point.z < lower.z)
{
dist_sq += Math_.Sqr(lower.z - point.z);
}
else if (point.z > upper.z)
{
dist_sq += Math_.Sqr(point.z - upper.z);
}
return(dist_sq);
}
/// <summary>
/// Clip a line segment to a bounding box returning the parametric values of the intersection.
/// Returns false if the line does not intersect with the bounding box.
/// Assumes initial values of 't0' and 't1' have been set.</summary>
public static bool Clip(BBox bbox, v4 point_, v4 direction_, ref float t0, ref float t1)
{
// Convert v4's to float arrays for efficient indexing
var lower = (float[])bbox.Lower();
var upper = (float[])bbox.Upper();
var point = (float[])point_;
var direction = (float[])direction_;
// For all three slabs
for (int i = 0; i != 3; ++i)
{
if (Math.Abs(direction[i]) < Math_.TinyF)
{
// Ray is parallel to slab. No hit if origin not within slab
if (point[i] < lower[i] || point[i] > upper[i])
{
return(false);
}
}
else
{
// Compute intersection t value of ray with near and far plane of slab
float u0 = (lower[i] - point[i]) / direction[i];
float u1 = (upper[i] - point[i]) / direction[i];
// Make u0 be intersection with near plane, u1 with far plane
if (u0 > u1)
{
Math_.Swap(ref u0, ref u1);
}
// Record the tightest bounds on the line segment
if (u0 > t0)
{
t0 = u0;
}
if (u1 < t1)
{
t1 = u1;
}
// Exit with no collision as soon as slab intersection becomes empty
if (t0 > t1)
{
return(false);
}
}
}
// Ray intersects all 3 slabs
return(true);
}
