#include <helianthus.h>
#include <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();
}