plasma effect demoscene in C width SDL

gistfile1.c

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

typedef unsigned char uchar;

void ppixel(SDL_Surface *screen, int x, int y, uchar r, uchar g, uchar b);

int main(int argc, char *argv[])
{
	SDL_Event event;
	Uint32 last_time;
	int cont = 1, x, y;
	uchar r[256], g[256], b[256];
	double f = 0;
	SDL_Surface *screen;
	SDL_Init(SDL_INIT_VIDEO);
	screen = SDL_SetVideoMode(320, 200, 32, SDL_HWSURFACE);

	for(x = 0; x < 256; x++)
	{
		r[x] = 255 - ceil((sin(3.14 * 2 * x / 255) + 1) * 127);
		g[x] = ceil((sin(3.14 * 2 * x / 127.0) + 1) * 64);
		b[x] = 255 - r[x];
	}
	
	last_time = SDL_GetTicks();
	while(cont == 1)
	{
		while(SDL_PollEvent(&event))
		{
			switch(event.type)
			{
				case SDL_QUIT:
					cont = 0;
					break;
			}
		}

		for(y = 0; y < 200; y++)
		{
			for(x = 0; x < 320; x++)
			{
				float c1 = sin(x / 50.0 + f + y / 200.0);
				float c2 = sqrt((sin(0.8 * f) * 160 - x + 160) * (sin(0.8 * f) * 160 - x + 160) + (cos(1.2 * f) * 100 - y + 100) * (cos(1.2 * f) * 100 - y + 100));
				c2 = sin(c2 / 50.0);
				float c3 = (c1 + c2) / 2;

				int res = ceil((c3 + 1) * 127);

				ppixel(screen, x, y, r[res], g[res], b[res]);
			}
		}

		SDL_Flip(screen);

		f += 0.1;
		if(SDL_GetTicks() - last_time < 40)
		{
			SDL_Delay(40 - (SDL_GetTicks() - last_time));
		}

		last_time = SDL_GetTicks();
	}

	
	SDL_Quit();

	return 0;
}

void ppixel(SDL_Surface *screen, int x, int y, uchar r, uchar g, uchar b)
{
	unsigned long color = SDL_MapRGB(screen->format, r, g, b);
	unsigned long *bufp;

	bufp = (unsigned long *) screen->pixels + y * screen->pitch / 4 + x;
	*bufp = color;
}