#include <math.h>

#include <helianthus.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 setColor(double x, unsigned char *pixel) {
  double h0 = 240;
  double h1 = 0;
  double h = h0 + (h1 - h0)*x;
  pixelSet(pixel, colorByHSV(h, 1, 1));
}


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() {
  julia(r, i);
  imageToExistingGLTexture(animationGetGLTexId(anim), 512, 512, pixels);
}


void init() {
  anim = createAnimationFromImageEx(512, 512, pixels, FALSE, FALSE, FALSE, FALSE);
  fractal();
}


void draw() {
  double dt = windowGetFrameTime();
  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() {
  windowSetTitle("Fractal");
  windowSetInit(&init);
  windowSetDraw(&draw);
  windowSetFrameRateEx(1, 100);
  windowRun();
  return 0;
}