class Triangle{
  
  public float[] x;
  public float[] y;
  
  public Triangle(float x1, float y1, float x2, float y2, float x3, float y3){
    this();
    float dx1 = x2-x1;
    float dx2 = x3-x1;
    float dy1 = y2-y1;
    float dy2 = y3-y1;
    float cross = dx1*dy2-dx2*dy1;
    boolean ccw = (cross>0);
    if (ccw){
      x[0] = x1; x[1] = x2; x[2] = x3;
      y[0] = y1; y[1] = y2; y[2] = y3;
    } else{
      x[0] = x1; x[1] = x3; x[2] = x2;
      y[0] = y1; y[1] = y3; y[2] = y2;
    }
  }
  
  public Triangle(){
    x = new float[3];
    y = new float[3];
  }
  
  public void draw(){
    draw(color(150,150,150),color(255,0,0));
  }
    
  public void draw(int fll, int strk){
    fill(fll);
//    stroke(strk);
    noStroke();
    if (isInside(mouseX,mouseY)) fill(0,255,0);
    triangle(x[0],y[0],x[1],y[1],x[2],y[2]);
  }
  
  public boolean isInside(float _x, float _y){
    float vx2 = _x-x[0]; float vy2 = _y-y[0];
    float vx1 = x[1]-x[0]; float vy1 = y[1]-y[0];
    float vx0 = x[2]-x[0]; float vy0 = y[2]-y[0];
    
    float dot00 = vx0*vx0+vy0*vy0;
    float dot01 = vx0*vx1+vy0*vy1;
    float dot02 = vx0*vx2+vy0*vy2;
    float dot11 = vx1*vx1+vy1*vy1;
    float dot12 = vx1*vx2+vy1*vy2;
    float invDenom = 1.0 / (dot00*dot11 - dot01*dot01);
    float u = (dot11*dot02 - dot01*dot12)*invDenom;
    float v = (dot00*dot12 - dot01*dot02)*invDenom;
    
    return ((u>0)&&(v>0)&&(u+v<1));    
  }
  
}