In a problem there consist of a 2D tunnel, a rectangle with two opposite sides removed as its faces, in which obstacles are only orthogonal rectangles (those whose edges are parallel to one of the edges of the tunnel) and circles. The light come from one end at any point in all directions. The problem contains as a subproblem checking whether the other end is illuminated, maybe partially, with all solution to that claiming that the light can pass from one end from another if and only if there exist a curve from one end to the other.
I don't think that's right because of there exist rooms unilluminable from any point light source. However, for this particular case I'm not sure if there exist such unilluminable tunnel, since the types of obstacles are limited. I'd appreciate it if you could help me construct such tunnel, or prove that this is impossible.