1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/mbrot.c	Tue Jun 19 06:48:38 2012 +0300
     1.3 @@ -0,0 +1,75 @@
     1.4 +/*
     1.5 +A simple interactive mandelbrot fractal explorer
     1.6 +Copyright (C) John Tsiombikas <nuclear@member.fsf.org>
     1.7 +
     1.8 +This program is free software: you can redistribute it and/or modify
     1.9 +it under the terms of the GNU General Public License as published by
    1.10 +the Free Software Foundation, either version 3 of the License, or
    1.11 +(at your option) any later version.
    1.12 +
    1.13 +This program is distributed in the hope that it will be useful,
    1.14 +but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    1.16 +GNU General Public License for more details.
    1.17 +
    1.18 +You should have received a copy of the GNU General Public License
    1.19 +along with this program.  If not, see <http://www.gnu.org/licenses/>.
    1.20 +*/
    1.21 +#include "mbrot.h"
    1.22 +#include "palette.h"
    1.23 +
    1.24 +static int mandelbrot(double cx, double cy, int iter);
    1.25 +
    1.26 +void draw_mandelbrot(unsigned char *pix, int xsz, int ysz, struct area *area, int iter)
    1.27 +{
    1.28 +	int i, j;
    1.29 +	double x, y, dx, dy;
    1.30 +
    1.31 +	dx = area->width / (double)xsz;
    1.32 +	dy = area->height / (double)ysz;
    1.33 +
    1.34 +	y = area->y;
    1.35 +	for(i=0; i<ysz; i++) {
    1.36 +		x = area->x;
    1.37 +		for(j=0; j<xsz; j++) {
    1.38 +			int res = mandelbrot(x, y, iter);
    1.39 +			/* visualize according to the number of iterations
    1.40 +			 * required to determine membership in the mandelbrot set.
    1.41 +			 * Members of the set will have res = iter and so col = PAL_SIZE-1
    1.42 +			 */
    1.43 +			int col = (PAL_SIZE - 1) * res / iter;
    1.44 +			*pix++ = palette[col].r;
    1.45 +			*pix++ = palette[col].g;
    1.46 +			*pix++ = palette[col].b;
    1.47 +			*pix++ = 0;
    1.48 +
    1.49 +			x += dx;
    1.50 +		}
    1.51 +		y += dy;
    1.52 +	}
    1.53 +}
    1.54 +
    1.55 +static int mandelbrot(double cx, double cy, int iter)
    1.56 +{
    1.57 +	int i;
    1.58 +	double zx, zy;	/* complex number Z */
    1.59 +
    1.60 +	/* start with Z0 = C */
    1.61 +	zx = cx;
    1.62 +	zy = cy;
    1.63 +
    1.64 +	for(i=0; i<iter; i++) {
    1.65 +		/* calculate Zn+1 = Zn * Zn + C */
    1.66 +		double x = (zx * zx - zy * zy) + cx;
    1.67 +		double y = (zy * zx + zx * zy) + cy;
    1.68 +		zx = x;
    1.69 +		zy = y;
    1.70 +
    1.71 +		/* escape if ||Z|| > 2 */
    1.72 +		if((x * x + y * y) > 4.0) {
    1.73 +			break;
    1.74 +		}
    1.75 +	}
    1.76 +
    1.77 +	return i;
    1.78 +}