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mandel.c
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mandel.c
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#include "imext.h"
#include <stdlib.h>
char evalstr[]="Mandlebrot renderer";
/* Example Mandlebrot generator */
/* input parameters
image is the image object.
*/
static
int
mandel(double x, double y, int max_iter) {
double xn, yn;
double xo, yo;
int iter = 1;
/* Z(n+1) = Z(n) ^2 + c */
/* printf("(%.2f, %.2f) -> \n", x,y); */
xo = x;
yo = y;
while( xo*xo+yo*yo <= 10 && iter < max_iter) {
xn = xo*xo-yo*yo + x;
yn = 2*xo*yo + y;
xo=xn;
yo=yn;
iter++;
}
return (iter == max_iter)?0:iter;
}
void
mandelbrot(i_img *im, double minx, double miny, double maxx, double maxy, int max_iter) {
int i,x,y;
int idx;
double divx, divy;
i_color icl[256];
srand(12235);
for(i=1;i<256; i++) {
icl[i].rgb.r = 100+(int) (155.0*rand()/(RAND_MAX+1.0));
icl[i].rgb.g = 100+(int) (155.0*rand()/(RAND_MAX+1.0));
icl[i].rgb.g = 100+(int) (155.0*rand()/(RAND_MAX+1.0));
}
icl[0].rgb.r = 0;
icl[0].rgb.g = 0;
icl[0].rgb.g = 0;
if (maxx <= minx)
maxx = minx + 1.0;
if (maxy <= miny)
maxy = miny + 1.0;
divx = (maxx - minx) / im->xsize;
divy = (maxy - miny) / im->ysize;
for(y = 0; y < im->ysize; y ++) {
for(x = 0; x < im->xsize; x ++ ) {
idx = mandel(minx + x*divx , miny + y*divy, max_iter);
idx = idx % 256;
i_ppix(im,x,y,&icl[idx]);
}
}
}