LIGHTS_OUT_OPENGL
OpenGL version of "Lights Out"

LIGHTS_OUT_OPENGL is a C program which sets up the "Lights Out" game and allows a user to try to solve it.

The Lights Out game is played on a rectangular board of squares, each representing a light that may be on or off. Clicking the mouse on a light switches it from on to off and vice versa. However, when you switch a light, you also switch the lights to the immediate left, right, above and below. (There is no "wrap around" however, in this basic version of the game.)

You start the game by specifying the width and height of the board to be used, and the number of moves the program should make in setting up the inital board. Specifying 10 moves, for instance, means that the program, starting from a board with all lights off, will randomly switch a light and its neighbors 10 times.

Usage:

lights_out_opengl width height moves

• width, the number of squares in the horizontal direction (try 10);
• height the number of squares in the vertical direction (try 10);
• moves the number of randomizing moves made to initialize the board (try 5 first!);

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

LIGHTS_OUT_OPENGL is available in a C version and a C++ version and a MATLAB version.

Related Data and Programs:

FERN_OPENGL, a C program which uses OpenGL to display the Barnsley fractal fern.

FLOOD_OPENGL, a C program which uses OpenGL to allow the user to select regions of a 2D image and flood them with color, by Art Wetzel.

LIFE_OPENGL, a C program which uses OpenGL to display the evolution of John Conway's "Game of Life", by Simon Green.

OPENGL, C programs which illustrate the use of the OpenGL graphics library;

SCREENSHOT_OPENGL, a C program which shows how a program using the OpenGL graphics library can save a screenshot of the graphics being displayed.

Reference:

1. Marlow Anderson, Todd Feil,
   Turning Lights Out With Linear Algebra,
   Mathematics Magazine,
   Volume 71, Number 4, October 1998, pages 300-303.
2. Edward Angel,
   Interactive Computer Graphics, a Top-Down Approach with OpenGL,
   Addison-Wesley, 2000,
   ISBN: 0-201-38597-X,
   LC: T385.A514.
3. Oscar Martin-Sanchez,
   Two Analyses of Lights Out,
   Mathematics Magazine,
   Volume 74, Number 4, October 2001, pages 295-304.

Source Code:

• lights_out_opengl.c, the source code.

Examples and Tests:

• display_6_9_20.png, a PNG image of the initial board you will see if you type

  lights_out_opengl 6 9 20

List of Routines:

• MAIN is the main program for LIGHTS_OUT_OPENGL.
• BOX_DRAW draws one box of the Lights Out array.
• DISPLAY generates the graphics output.
• I4_MAX returns the maximum of two I4's.
• I4_MIN returns the minimum of two I4's.
• I4_UNIFORM returns a scaled pseudorandom I4.
• MY_INIT initializes OpenGL state variables dealing with viewing and attributes.
• MY_MOUSE reacts to mouse events.
• R4_ABS returns the absolute value of an R4.
• R4_NINT returns the nearest integer to an R4.
• STATE_RANDOMIZE randomizes the state.
• STATE_UPDATE updates the state after button (I,J) has been pressed.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C source codes.