game of life

gol.c

#include <stdio.h>
#include <math.h>
#include <SDL/SDL.h>
#include <SDL/SDL_draw.h>

#define SCREEN_W 320
#define SCREEN_H 320

#define CELL_SIZ 10

#define W   SCREEN_W / CELL_SIZ
#define H   SCREEN_H / CELL_SIZ

SDL_Surface *scr;

int cells[W][H];
int cells2[W][H];
int (*cellsPtr)[H] = cells;
int (*cells2Ptr)[H] = cells2;
int (*cellsTmp)[H];


int done;

int start;

void life();

void handle_keys()
{
    int x, y;
    static int cx, cy;

    SDL_Event event;
    while (SDL_PollEvent(&event)) {
        SDL_GetMouseState(&x, &y);
        cx = x / CELL_SIZ;
        cy = y / CELL_SIZ;

        switch (event.type) {
            case SDL_KEYDOWN:
                if (event.key.keysym.sym == SDLK_ESCAPE)
                    exit(0);
                else if (event.key.keysym.sym == SDLK_SPACE) 
                    start = !start;
                else if (event.key.keysym.sym == SDLK_n)
                    life();
                break;
            case SDL_MOUSEBUTTONDOWN:
                cellsPtr[cx][cy] = !cellsPtr[cx][cy];
                break;
            case SDL_QUIT:
                exit(0);
        }
    }

    /* hover display */
    if (SDL_MUSTLOCK(scr))
        SDL_LockSurface(scr);
        Draw_FillRect(scr, cx * CELL_SIZ, cy * CELL_SIZ, CELL_SIZ, CELL_SIZ, SDL_MapRGB(scr->format, 10, 10, 20));
    if (SDL_MUSTLOCK(scr))
        SDL_UnlockSurface(scr);

}

void draw_cells()
{
    int i, j;

    for (i = 0; i < H; i++) {
        for (j = 0; j < W; j++) {
            if (cellsPtr[j][i]) {
                if (SDL_MUSTLOCK(scr))
                    SDL_LockSurface(scr);
                Draw_FillRect(scr, j * CELL_SIZ, i * CELL_SIZ, CELL_SIZ, CELL_SIZ, SDL_MapRGB(scr->format, 10, 10, start ? 250 : 150));
                if (SDL_MUSTLOCK(scr))
                    SDL_UnlockSurface(scr);
            }
        }
    }
}

void life()
{
    int i, j;

    for (i = 0; i < H; i++) 
        for (j = 0; j < W; j++) {
            cells2Ptr[i][j] = 0;
            int num_alive_adj = 0;
            num_alive_adj += cellsPtr[i][j-1];
            num_alive_adj += cellsPtr[i-1][j-1];
            num_alive_adj += cellsPtr[i-1][j];
            num_alive_adj += cellsPtr[i-1][j+1];
            num_alive_adj += cellsPtr[i][j+1];
            num_alive_adj += cellsPtr[i+1][j+1];
            num_alive_adj += cellsPtr[i+1][j];
            num_alive_adj += cellsPtr[i+1][j-1];

            if (cellsPtr[i][j]) {
                if (num_alive_adj == 2 || num_alive_adj == 3) /* survive */
                    cells2Ptr[i][j] = 1;
                else if (num_alive_adj > 3) /* overpopulation */
                    cells2Ptr[i][j] = 0;
                else if (num_alive_adj <= 2)
                    cells2Ptr[i][j] = 0;
            } else {
                if (num_alive_adj == 3) /* birth! */
                    cells2Ptr[i][j] = 1;
            }
        }

    cellsTmp = cellsPtr;
    cellsPtr = cells2Ptr;
    cells2Ptr = cellsTmp;
}


int main(int argc, char* argv[])
{
    Uint32 second; 
    int fps = 0;
    int life_second;

    SDL_Init(SDL_INIT_VIDEO);
    atexit(SDL_Quit);
    scr = SDL_SetVideoMode(SCREEN_W, SCREEN_H, 32, SDL_SWSURFACE | SDL_DOUBLEBUF);
    SDL_ShowCursor(SDL_ENABLE);

    second = SDL_GetTicks() + 1000;
    life_second = SDL_GetTicks() + 300;

    while(!done) {

        SDL_FillRect(scr, NULL, 0);
        handle_keys();

        if (start) {
            /* slow down a bit */
            if (SDL_GetTicks() > life_second) {
                life_second = SDL_GetTicks() + 300;
                life();
            }
        }

        draw_cells();
        SDL_Flip(scr);

        if (SDL_GetTicks() > second) {
            fps = 0;
            second = SDL_GetTicks() + 1000;
        }

        SDL_Delay(30);
        fps++;
    }

    return 0;
}