mandelbrot.c

mandelbrot.c

/* See: https://stackoverflow.com/questions/16124127/improvement-to-my-mandelbrot-set-code */

#include <math.h>
#include <stdlib.h>
#include <time.h>
#include <stdio.h>

unsigned char palette[48] = {
    66, 30, 15,
    25, 7, 26,
    9, 1, 47,
    4, 4, 73,
    0, 7, 100,
    12, 44, 138,
    24, 82, 177,
    57, 125, 209,
    134, 181, 229,
    211, 236, 248,
    241, 233, 191,
    248, 201, 95,
    255, 170, 0,
    204, 128, 0,
    153, 87, 0,
    106, 52, 3
};

void color(int red, int green, int blue, int bg)
{
    if (bg) {
	printf("\033[48;2;%d;%d;%dm", red, green, blue);
    } else {
	printf("\033[38;2;%d;%d;%dm", red, green, blue);
	// printf("█"); // U+2588
	printf("▄"); // U+2584
	printf("\033[m");
    }
}

int main(int argc, char *argv[])
{
    int w = 80, h = 24, x, y;
    double pixratio = 0.5;
    //each iteration, it calculates: newz = oldz*oldz + p, where p is the current pixel, and oldz stars at the origin
    double pr, pi;                   //real and imaginary part of the pixel p
    double newRe, newIm, oldRe, oldIm;   //real and imaginary parts of new and old z
    double zoom = 1, moveX = -0.5, moveY = 0; //you can change these to zoom and change position
    int maxIterations = 1000;//after how much iterations the function should stop

    double xscale = (pixratio*w/h) / (0.5 * zoom * w);
    double yscale = 1.0 / (0.5 * zoom * h);

    clock_t begin, end;
    double time_spent;

    begin = clock();

#if 0
    fprintf(stderr, "%f %f %f %f\n",
	    (0 - w / 2) * xscale + moveX, (0 - h / 2) * yscale + moveY,
	    ((w-1) - w / 2) * xscale + moveX, ((h-1) - h / 2) * yscale + moveY
	    );
#endif

    //loop through every pixel
    for(y = 0; y < h; y++)
    {
	for(x = 0; x < w; x++)
	{
	    int y2;
	    for(y2=0; y2<2; y2++)
	    {
		//calculate the initial real and imaginary part of z, based on the pixel location and zoom and position values
		pr = (x - w / 2) * xscale + moveX;
		pi = (y - h / 2 + y2*0.5) * yscale + moveY;
		newRe = newIm = oldRe = oldIm = 0; //these should start at 0,0
		//"i" will represent the number of iterations
		int i;
		//start the iteration process
		for(i = 0; i < maxIterations; i++)
		{
		    //remember value of previous iteration
		    oldRe = newRe;
		    oldIm = newIm;
		    //the actual iteration, the real and imaginary part are calculated
		    newRe = oldRe * oldRe - oldIm * oldIm + pr;
		    newIm = 2 * oldRe * oldIm + pi;
		    //if the point is outside the circle with radius 2: stop
		    if((newRe * newRe + newIm * newIm) > 4) break;
		}

		if(i == maxIterations || i == 0)
		    color(0, 0, 0, !y2); // black
		else
		{
#ifdef LOG2PAL
		    double z = sqrt(newRe * newRe + newIm * newIm);
		    int brightness = 256. * log2(1.75 + i - log2(log2(z))) / log2(maxIterations);
		    if (brightness<0) brightness = 0;
		    color(brightness, brightness, brightness, !y2);
#else
		    unsigned char * p = palette+(i&15)*3;
		    color(p[0], p[1], p[2], !y2);
#endif
		}
	    }
	}
	printf("\n");
    }

    end = clock();

    time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
    // fprintf(stderr,"Elapsed time: %.2lf seconds.\n", time_spent);
}