SDL 77 is a C library for game development in FORTRAN 77 that provides some glue code to access the software renderer of SDL 1.2. Common FORTRAN/C calling conventions are used for mixed-language programming (compatible to f77, f2c, g77, GNU Fortran, Digital/Compaq, Portland Group, SGI, Sun, …). For modern Fortran 2008 interface bindings to SDL 2.0, see fortran-sdl2.

The library has the following dependencies:

• SDL 1.2
• SDL_image
• SDL_mixer

You may have to install additional development headers. See the documentation for the API description.

First, install the dependencies. On FreeBSD, run:

# pkg install audio/sdl_mixer devel/sdl12 graphics/sdl_image

Then, build libSDL77.a with GCC by executing the provided Makefile:

$ make

You may want to compile the library without the SDL_image dependency (restricting the supported image formats to BMP only):

$ make noimage

To build without SDL_mixer, run:

$ make nomixer

And only bare SDL 1.2, without SDL_image and SDL_mixer:

$ make nolibs

Link your FORTRAN 77 program against libSDL77.a -lSDL -lSDL_image -lSDL_mixer. Alternatively, you can simply link with object file SDL77.o instead of libSDL77.a.

The following example program demo.f in ANSI FORTRAN 77 opens an SDL 1.2 window and fills a green rectangle.

C     ******************************************************************
C
C     SDL 77 DEMO PROGRAM IN FORTRAN 77.
C
C     ******************************************************************
      PROGRAM DEMO
C
C     EXTERNAL PROCEDURES.
C
      EXTERNAL GCLOSE, GOPEN
      EXTERNAL GCOLOR, GDELAY, GEVENT, GFILLR, GFLUSH, GLAYER
      INTEGER  GKEY
C
C     PARAMETERS.
C
      INTEGER EQUIT, IDELAY, IW, IH, KESC
      PARAMETER (EQUIT=12, IDELAY=50, IW=640, IH=480, KESC=27)
C
C     VARIABLES.
C
      INTEGER IEVENT, ISTAT
      LOGICAL DONE
      DATA DONE /.FALSE./
C
C     OPEN SDL 1.2 WINDOW.
C
      CALL GOPEN(IW, IH, 'FORTRAN' // ACHAR(0), ISTAT)
      IF (ISTAT .NE. 0) STOP
C
C     MAIN LOOP: POLLS EVENTS, FILLS RECTANGLE, FLIPS BUFFER TO SCREEN.
C
   10 CONTINUE
C
C     PROCESS EVENTS.
C
   20 CONTINUE
      CALL GEVENT(IEVENT, ISTAT)
      IF (IEVENT .EQ. EQUIT) DONE = .TRUE.
      IF (ISTAT .EQ. 1) GOTO 20
C
C     PROCESS KEYBOARD INPUT.
C
      IF (GKEY(KESC) .EQ. 1) DONE = .TRUE.
C
C     FILL RECTANGLE.
C
      CALL GLAYER(0)
      CALL GCOLOR(0, 255, 0)
      CALL GFILLR(50, 50, 150, 150)
C
C     FLIP TO SCREEN.
C
      CALL GFLUSH()
      CALL GDELAY(IDELAY)
      IF (.NOT. DONE) GOTO 10
C
C     QUIT.
C
      CALL GCLOSE()
      END

Link the demo program against SDL 77, SDL, SDL_image, and SDL_mixer:

$ gfortran -o demo demo.f libSDL77.a -lSDL -lSDL_image -lSDL_mixer
$ ./demo

To compile without SDL_image and SDL_mixer, run:

$ make nolibs
$ gfortran -o demo demo.f libSDL77.a -lSDL
$ ./demo

The code is compatible to f2c as well:

$ f2c demo.f
demo.f:
   MAIN demo:
$ gcc -o demo demo.c libSDL77.a -lSDL -lSDL_image -lSDL_mixer -lf2c -lm
$ ./demo

Some example programs can be found in directory examples/:

• archi draws the Archimedean spiral.
• bship draws the burning ship fractal.
• engine renders a 2.5-D environment through ray-casting.
• fern draws a Barnsley fern fractal.
• fire renders the DOOM fire effect.
• fizzle demonstrates a fizzle-fade effect based on Fisher-Yates shuffle.
• flower draws a sunflower fractal.
• font prints text with a bitmap font.
• mode7 shows affine transformation for perspective correction.
• plasma renders animated plasma effect.
• root3 is another fractal demo.
• shuttle renders the wireframe model of a space shuttle.
• smoke renders a 3-D chaotic attractor.
• sphere draws a shaded sphere.
• track plays audio track in OGG format and optionally WAV sound effect.

Build the examples with:

$ make examples

ISC