# Shadow of a Square Under a Point Source of Light

**r**controls the size of the square Point

**S**is the light source, and

**S**is located at

**P**controls the center of the square, and the coordinates of

**P**are

**Q**controls the orientation of the square (think of

**Q**as a knob on a joystick, where the joystick is perpendicular and attached to the square at

**P**).

**θ**tilts the square and

**φ**rotates it about a vertical axis through its center). You can also move point

**A**to spin the square about the

**PQ**axis.

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