#include <helianthus.h></helianthus.h>

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

Animation anim = 0;

unsigned char pixels[512][512][4];

double r = 0.4, i = 0.6;

double mx, my, zmx, zmy;

double z = 1/128.0;

double cx = -2;

double cy = -2;

void hsvToRgb(double h, double s, double v, unsigned char *pixel) {

  h -= floor(h/360)*360;

  s /= 100;

  v = v/100*255;

  s = s > 0 ? (s < 1 ? s : 1) : 0;

  v = v > 0 ? (v < 255 ? v : 255) : 0;

  h /= 60.0;

  int i = (int)h;

  double f = h - i;

  int pp = v*(1 - s);

  int qq = v*(1 - s*f);

  int tt = v*(1 - s*(1 - f));

  unsigned char p = (unsigned char)(pp > 0 ? (pp < 255 ? pp : 255) : 0);

  unsigned char q = (unsigned char)(qq > 0 ? (qq < 255 ? qq : 255) : 0);

  unsigned char t = (unsigned char)(tt > 0 ? (tt < 255 ? tt : 255) : 0);

  unsigned char u = (unsigned char)v;

  switch(i) {

    case  0: pixel[0] = u, pixel[1] = t, pixel[2] = p; break;

    case  1: pixel[0] = q, pixel[1] = u, pixel[2] = p; break;

    case  2: pixel[0] = p, pixel[1] = u, pixel[2] = t; break;

    case  3: pixel[0] = p, pixel[1] = q, pixel[2] = u; break;

    case  4: pixel[0] = t, pixel[1] = p, pixel[2] = u; break;

    default: pixel[0] = u, pixel[1] = p, pixel[2] = q; break;

  }

  pixel[3] = 255;

}

void setColor(double x, unsigned char *pixel) {

  double h0 = 240;

  double h1 = 0;

  double h = h0 + (h1 - h0)*x;

  hsvToRgb(h, 100, 100, pixel);

}

void julia(double r, double i) {

  for(int y = 0; y < 512; ++y) {

    for(int x = 0; x < 512; ++x) {

      double rr = x*z + cx;

      double ii = y*z + cy;

      int b;

      for(b = 0; b < 64; ++b) {

        if (rr*rr + ii*ii > 4) break;

        double x = rr*rr - ii*ii + r;

        ii = 2*rr*ii + i;

        rr = x;

      }

      setColor(b/64.0, pixels[y][x]);

    }

  }

}

void fractal() {

  if (anim) animationDestroy(anim);

  julia(r, i);

  anim = createAnimationFromImageEx(512, 512, pixels, FALSE, FALSE, FALSE, FALSE);

}

void init() {

  fractal();

}

void draw() {

  double dt = worldGetFrameTime();

  int changed = 0;

  if (mouseDown("middle")) {

    r += (mouseX() - mx)*z/10;

    i += (mouseY() - my)*z/10;

    changed = 1;

  }

  if (mouseDown("left") || mouseDown("right")) {

    double k = pow(4, dt);

    if (mouseDown("left")) k = 1/k;

    cx += mouseX()*z*(1 - k);

    cy += mouseY()*z*(1 - k);

    z *= k;

    changed = 1;

  }

  mx = mouseX();

  my = mouseY();

  if (changed) fractal();

  fill(colorByName("white"));

  rectTextured(anim, 0, 0, 512, 512);

}

int main() {

  worldSetInit(&init);

  worldSetDraw(&draw);

  worldSetFrameRateEx(1, 100);

  worldRun();

}