Conway's Game of Life, written in C/OpenGL. Uses bitmasking for optimization. Build with -lglut -lGL.

main.c

#include <gl.h>
#include <freeglut.h>

#define LIVE_MASK 0b10000
#define WIDTH  1366
#define HEIGHT 768

short ** front;
short ** back;

int i, j;
int o, k;
short surr;

int milliTime() {
	struct timeval tv;
	gettimeofday(&tv, NULL );
	return (tv.tv_sec * 1000) + (tv.tv_usec / 1000);
}

inline short* get(short ** map, int x, int y) {
	if (x < 0) {
		x += WIDTH;
	} else if (x >= WIDTH) {
		x -= WIDTH;
	}
	if (y < 0) {
		y += HEIGHT;
	} else if (y >= HEIGHT) {
		y -= HEIGHT;
	}
	return &(map[x][y]);
}

void genBuffers() {
	front = malloc(WIDTH * sizeof(short*));
	back = malloc(WIDTH * sizeof(short*));
	for (i = 0; i < WIDTH; i++) {
		front[i] = malloc(HEIGHT * sizeof(short));
		back[i] = malloc(HEIGHT * sizeof(short));
		for (j = 0; j < HEIGHT; j++) {
			front[i][j] = rand() & LIVE_MASK;
			back[i][j] = 0;
		}
	}
}

void clearSurr(short ** map) {
	for (i = 0; i < WIDTH; i++) {
		for (j = 0; j < HEIGHT; j++) {
			map[i][j] &= LIVE_MASK;
		}
	}
}

void updateSurr(short ** map) {
	for (i = 0; i < WIDTH; i++) {
		for (j = 0; j < HEIGHT; j++) {
			if ((map[i][j] & LIVE_MASK) == LIVE_MASK) {
				for (o = -1; o <= 1; o++) {
					for (k = -1; k <= 1; k++) {
						if (o || k) {
							*(get(map, i + o, j + k)) += 1;
						}
					}
				}
			}
		}
	}
}

void reshape(int width, int height) {
	glMatrixMode(GL_PROJECTION);
	glOrtho(0.0, WIDTH, 0.0, HEIGHT, -1.0, 1.0);
}

void render(void) {
	glClear(GL_COLOR_BUFFER_BIT);
	glBegin(GL_QUADS);
	for (i = 0; i < WIDTH; i++) {
		for (j = 0; j < HEIGHT; j++) {
			surr = front[i][j] & ~LIVE_MASK;
			if ((surr > 0 && rand() < RAND_MAX / 1000) || surr == 3
					|| ((front[i][j] & LIVE_MASK) && surr == 2)) {
				glColor3f(((float) i) / ((float) WIDTH), 1.0,
						((float) j) / ((float) HEIGHT));
				glVertex2f(i, j);
				glVertex2f(i, j + 1);
				glVertex2f(i + 1, j + 1);
				glVertex2f(i + 1, j);
				back[i][j] |= LIVE_MASK;

				/*
				 * UNROLLED
				 * for (o = -1; o <= 1; ++o) {
				 * 	for (k = -1; k <= 1; ++k) {
				 * 	if (o || k) {
				 * 	*(get(back, i + o, j + k)) += 1;
				 * }
				 * }
				 * }
				 */

				*(get(back, i + 1, j)) += 1;
				*(get(back, i - 1, j)) += 1;

				*(get(back, i - 1, j - 1)) += 1;
				*(get(back, i, j - 1)) += 1;
				*(get(back, i + 1, j - 1)) += 1;

				*(get(back, i - 1, j + 1)) += 1;
				*(get(back, i, j + 1)) += 1;
				*(get(back, i + 1, j + 1)) += 1;
			}
			front[i][j] = 0;
		}
	}
	glEnd();
	glFlush();

	short ** temp = back;
	back = front;
	front = temp;
}

void keyPress(unsigned char c, int x, int y) {
	if (c == 'f') {
		glutFullScreen();
	} else if (c == 'w') {
		glutIconifyWindow();
	}
}

int main(int argc, char ** argv) {

	glutInit(&argc, argv);
	genBuffers();
	updateSurr(front);
	glutInitWindowPosition(0, 0);
	glutInitWindowSize(WIDTH, HEIGHT);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutCreateWindow("Test");

	//glutReshapeFunc(reshape);
	glutDisplayFunc(render);
	glutKeyboardUpFunc(keyPress);
	glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE,
			GLUT_ACTION_GLUTMAINLOOP_RETURNS);
	reshape(WIDTH, HEIGHT);

	glutIdleFunc(glutPostRedisplay);
	glutMainLoop();

	for (i = 0; i < WIDTH; i++) {
		free(front[i]);
		free(back[i]);
	}
	free(front);
	free(back);
	return 0;
}