simple SDL example

gc.go

package gc

import (
	"launchpad.net/gocheck"
)

func Failure(c *gocheck.C) func() {
	return func() {
		// fails immediately
		c.Fail()
	}
}

sdl.c

#include "SDL/SDL.h"
#include <assert.h>
#include <math.h>

/* This macro simplifies accessing a given pixel component on a surface. */
#define pel(surf, x, y, rgb) ((unsigned char *)(surf->pixels))[y*(surf->pitch)+x*3+rgb]


int main(int argc, char *argv[])
{
    int x, y, t;

    /* Event information is placed in here */
    SDL_Event event;

    /* This will be used as our "handle" to the screen surface */
    SDL_Surface *scr;

    SDL_Init(SDL_INIT_VIDEO);

    /* Get a 640x480, 24-bit software screen surface */
    scr = SDL_SetVideoMode(640, 480, 24, SDL_SWSURFACE);
    assert(scr);

    /* Ensures we have exclusive access to the pixels */
    SDL_LockSurface(scr);

    for(y = 0; y < scr->h; y++)
        for(x = 0; x < scr->w; x++)
        {
                /* This is what generates the pattern based on the xy co-ord */
                t = ((x*x + y*y) & 511) - 256;
                if (t < 0)
                        t = -(t + 1);

                /* Now we write to the surface */
                pel(scr, x, y, 0) = 255 - t; //red
                pel(scr, x, y, 1) = t; //green
                pel(scr, x, y, 2) = t; //blue
        }
    SDL_UnlockSurface(scr);

    /* Copies the `scr' surface to the _actual_ screen */
    SDL_UpdateRect(scr, 0, 0, 0, 0);


    /* Now we wait for an event to arrive */
    while(SDL_WaitEvent(&event))
    {
        /* Any of these event types will end the program */
        if (event.type == SDL_QUIT
         || event.type == SDL_KEYDOWN
         || event.type == SDL_KEYUP)
                break;
    }
    SDL_Quit();
    return EXIT_SUCCESS;
}