* Use the Camera slider to move the location of the camara.[br]* Use the mouse to move the pixel in the rendering window. The pixel will turn red when the line of sight intersects the sphere.[br]* If you check "Trace On" and move the pixel, you will get a simulation of the image of the sphere being drawn on the rendering window. Use the arrow keys to scan the pixel horizontally or vertically across the rending window.[br]* Move the sphere by moving the center with the mouse or entering the coordinates in the textbox. The radius can be changed via the textbox.[br]* The size of the rendering window can be changed with the slider.[br][br](Based on original concept by Kevin Cox, Bentley University)