/* SWILL Mandelbrot example */
#include "swill.h"
#include "gd.h"
/* Structure containing plot data */
typedef struct {
double Xmin;
double Xmax;
double Ymin;
double Ymax;
int Tolerance;
gdImagePtr im;
} MandelData;
/* Handler function that draws an image */
void mandel(FILE *f, MandelData *m) {
double scalingx;
double scalingy;
double zr,zi,ztr,zti,cr,ci;
double cscale;
int i,j,n;
scalingx = (m->Xmax-m->Xmin)/m->im->sx;
scalingy = (m->Ymax-m->Ymin)/m->im->sy;
cscale = 256.0/m->Tolerance;
for (i = 0; i < m->im->sx; i++) {
for (j = 0; j < m->im->sy; j++) {
zr = scalingx*i + m->Xmin;
zi = scalingy*j + m->Ymin;
cr = zr;
ci = zi;
n = 0;
while (n < m->Tolerance) {
ztr = zr*zr-zi*zi + cr;
zti = 2*zr*zi + ci;
zr = ztr;
zi = zti;
if (ztr*ztr + zti*zti > 20) break;
n = n + 1;
}
if (n >= m->Tolerance) gdImageSetPixel(m->im,i,j,0);
else gdImageSetPixel(m->im,i,j,(int) (n*cscale));
}
}
gdImagePng(m->im,f);
}
/* Handler that produces HTML form for changing values */
void mandelpage(FILE *f, MandelData *m) {
double xmin, xmax, ymin, ymax;
double xshift,yshift;
int tol;
fprintf(f,"\n");
if (!swill_getargs("d(xmin)d(xmax)d(ymin)d(ymax)i(tol)", &xmin,&xmax,&ymin,&ymax,&tol)) {
fprintf(f,"Missing form variable!\n");
} else {
m->Xmin = xmin;
m->Xmax = xmax;
m->Ymin = ymin;
m->Ymax = ymax;
m->Tolerance = tol;
}
/* Link to image picture */
fprintf(f,"![](\"mandel.png\")
\n");
xshift = (m->Xmax - m->Xmin)/4;
yshift = (m->Ymax - m->Ymin)/4;
fprintf(f,"\n");
fprintf(f,"Xmin-xshift,m->Xmax-xshift,m->Ymin,m->Ymax,m->Tolerance);
fprintf(f,"\">[ Left ]");
fprintf(f,"Xmin+xshift,m->Xmax+xshift,m->Ymin,m->Ymax,m->Tolerance);
fprintf(f,"\">[ Right ]");
fprintf(f,"Xmin,m->Xmax,m->Ymin-yshift,m->Ymax-yshift,m->Tolerance);
fprintf(f,"\">[ Up ]");
fprintf(f,"Xmin,m->Xmax,m->Ymin+yshift,m->Ymax+yshift,m->Tolerance);
fprintf(f,"\">[ Down ]");
fprintf(f,"Xmin+xshift,m->Xmax-xshift,m->Ymin+yshift,m->Ymax-yshift,m->Tolerance);
fprintf(f,"\">[ Zoom in ]");
fprintf(f,"Xmin-xshift,m->Xmax+xshift,m->Ymin-yshift,m->Ymax+yshift,m->Tolerance);
fprintf(f,"\">[ Zoom out ]");
fprintf(f,"
\n");
/* Form to change values manually */
fprintf(f,"\n");
fprintf(f,"\n");
}
int main(int argc, char **argv) {
int i;
MandelData *m;
printf("Mandelbrot set viewer\n");
m = (MandelData *) malloc(sizeof(MandelData));
m->Xmin = -2.0;
m->Xmax = 2.0;
m->Ymin = -2.0;
m->Ymax = 2.0;
m->Tolerance = 50;
m->im = gdImageCreate(400,400);
/* Allocate colormap */
for (i = 0; i < 256; i++) {
gdImageColorAllocate(m->im,i/2,i,i);
}
if (swill_init(8080)) {
printf("Server listening on port 8080\n");
} else {
printf("Couldn't start server!\n");
exit(1);
}
swill_handle("mandel.png", mandel, m);
swill_handle("mandelpage.html", mandelpage,m);
swill_handle("index.html",mandelpage,m);
while (1) {
swill_serve();
}
}