// Returns false is there is no intersection
private bool GetMousePositionOnXZPlane(Point mousePosition, out Point3D intersectionPoint)
{
Point3D rayOrigin;
Vector3D rayDirection;
// Calculate the 3D ray that goes from the mouse position into the 3D scene
bool success = Camera1.CreateMouseRay3D(mousePosition, out rayOrigin, out rayDirection);
bool hasIntersection;
intersectionPoint = new Point3D();
if (success && rayDirection.Y != 0)
{
// Get intersection of ray and xz plane - defined by N=(0,1,0), P=(0,0,0)
// Because we use the xz plane the intersection formula is very simple:
double t = (-rayOrigin.Y) / rayDirection.Y;
if (t > 0) // we have an intersection
{
// Get the 3d point of intersection
intersectionPoint = rayOrigin + t * rayDirection;
// Skip intersections that are far away
if (intersectionPoint.Z > HALF_MOUSE_LINE_LENGTH || intersectionPoint.Z < -HALF_MOUSE_LINE_LENGTH || intersectionPoint.X > HALF_MOUSE_LINE_LENGTH || intersectionPoint.X < -HALF_MOUSE_LINE_LENGTH)
{
hasIntersection = false;
}
else
{
hasIntersection = true;
}
}
else
{
hasIntersection = false;
}
}
else
{
hasIntersection = false;
}
return(hasIntersection);
}
