c – 返回值1.#INF000

float Ray::Intersects(BoundingBox boundingBox)
{
// direction is unit direction vector of the ray
D3DXVECTOR3 dirfrac(
    1.0f / direction.x,1.0f / direction.y,1.0f / direction.z);

D3DXVECTOR3 min = boundingBox.Min();
D3DXVECTOR3 max = boundingBox.Max();

//min and max are the negative and positive corners of the bounding box
float t1 = (min.x - origin.x) * dirfrac.x;
float t2 = (max.x - origin.x) * dirfrac.x;
float t3 = (min.y - origin.y) * dirfrac.y;
float t4 = (max.y - origin.y) * dirfrac.y;
float t5 = (min.z - origin.z) * dirfrac.z;
float t6 = (max.z - origin.z) * dirfrac.z;

float tmin = max(max(min(t1,t2),min(t3,t4)),min(t5,t6));
float tmax = min(min(max(t1,max(t3,max(t5,t6));

// if tmax < 0,ray (line) is intersecting AABB,but whole AABB is behind us
if (tmax < 0) { return -1; }

// if tmin > tmax,ray doesn't intersect AABB
if (tmin > tmax) { return -1; } //HERE TMIN IS 1.#INFOOO

return tmin; //THIS IS NEVER REACHED
}