// Real-time Collision Detection, p179.
public float RayCast(Vector3 from, Vector3 to, float maxFraction = 1.0f)
{
float tMin = float.MinValue;
float tMax = float.MaxValue;
Vector3 d = to - from;
Vector3 absD = VectorUtil.Abs(d);
for (int i = 0; i < 3; ++i)
{
float dComp = VectorUtil.GetComopnent(d, i);
float absDComp = VectorUtil.GetComopnent(absD, i);
float fromComp = VectorUtil.GetComopnent(from, i);
float minComp = VectorUtil.GetComopnent(Min, i);
float maxComp = VectorUtil.GetComopnent(Max, i);
if (absDComp < float.Epsilon)
{
// parallel?
if (fromComp < minComp || maxComp < fromComp)
{
return(float.MinValue);
}
}
else
{
float invD = 1.0f / dComp;
float t1 = (minComp - fromComp) * invD;
float t2 = (maxComp - fromComp) * invD;
if (t1 > t2)
{
float temp = t1;
t1 = t2;
t2 = temp;
}
tMin = Mathf.Max(tMin, t1);
tMax = Mathf.Min(tMax, t2);
if (tMin > tMax)
{
return(float.MinValue);
}
}
}
// does the ray start inside the box?
// does the ray intersect beyond the max fraction?
if (tMin < 0.0f || maxFraction < tMin)
{
return(float.MinValue);
}
// intersection detected
return(tMin);
}