public Vector3 GetCollisionPointWithViewBox(Vector3 origin, Vector3 direction)
{
Vector3 point = Vector3.zero;
foreach (var line in viewbox)
{
Vector2 q = line.start;
Vector2 s = line.end - line.start;
Vector2 p = SMath.Vec3ToVec2(origin);
Vector2 r = SMath.Vec3ToVec2(direction);
// The intersection is where q + u*s == p + t*r, and 0 <= u <= 1 && 0 <= t
// t = (q − p) × s / (r × s)
// u = (q − p) × r / (r × s)
float crossRS = SMath.CrossProduct2D(r, s);
float crossQP_S = SMath.CrossProduct2D(q - p, s);
float crossQP_R = SMath.CrossProduct2D(q - p, r);
if (crossRS == 0)
{
// TODO: other situations
}
else
{
float t = crossQP_S / crossRS;
float u = crossQP_R / crossRS;
if (0 <= u && u <= 1 && 0 <= t)
{
point = q + u * s;
break;
}
}
}
return(point);
}