#include <math.h>
#include <helianthus.h>


#define COUNT 9


unsigned int colors[3] = { COLOR_RED, COLOR_BLUE, COLOR_YELLOW };


void drawTriangle(double x, double y, double radius, double angle, unsigned int color, int level) {
  if (level <= 0) {
    saveState();
    strokeWidth(radius * 0.1);
    fill(color);
    regularPolygon(x, y, 3, radius, angle);
    restoreState();
  } else {
    --level;
    double r = radius/((COUNT + 3)/2);
    radius -= r;

    saveState();
    noStroke();
    fill(colorWithAlpha(color, 0.5));
    regularPolygon(x, y, 3, radius - r - r, angle);
    restoreState();

    double a0 = angle*PI/180;
    double da = 2*PI/3;
    for(int i = 0; i < 3; ++i) {
      double x0 = x + radius*cos(a0 + i*da);
      double y0 = y + radius*sin(a0 + i*da);
      double x1 = x + radius*cos(a0 + i*da + da);
      double y1 = y + radius*sin(a0 + i*da + da);
      double dx = cos(a0 + i*da + da/2)*r/2;
      double dy = sin(a0 + i*da + da/2)*r/2;
      for(int j = 0; j < COUNT; ++j) {
        double k = (double)j/(COUNT + 1);
        double xx = x0*(1 - k) + x1*k;
        double yy = y0*(1 - k) + y1*k;
        if (j % 2) { xx -= dx; yy -= dy; }
        double a = angle + j*180;
        drawTriangle(xx, yy, r, a, colors[i], level);
      }
    }
  }
}


void init() {
}


void draw() {
  double w = windowGetWidth();
  double h = windowGetHeight();

  saveState();
  translate(w/2, h/2);
  drawTriangle(0, 0, 400, 0, colors[0], 2);
  restoreState();
}


int main() {
  windowSetResizable(TRUE);
  windowSetVariableFrameRate();
  windowSetInit(&init);
  windowSetDraw(&draw);
  windowRun();
}