// normal vector of the plane is the same everywhere
public double findIntersection(Ray r)
{
Vector dir = r.direction;
double a = dir.dotProduct(norm);
if (a == 0)
{
// no intersection
return(-99);
}
else
{
Vector originToDir = r.orgin + r.direction.norm().ScalarMultiply(distance).negate();
double b = originToDir.norm().dotProduct();
return(b);
}
}