/********************************************************************
  File:         sierpinski.cc 
  Author:       Dana Vrajitoru
                Based on the example provided in 
                E. Angel, Interactive Computer Graphics.
  Project:      An implementation of the Sierpinski gasket.
  Last updated: January 30, 2017.

  Drawing a fractal using triangles.

********************************************************************/

#include "glheader.h"
#include "interface.h"
#include "sierpinski.h"

// display one triangle
void triangle( Point2 a, Point2 b, Point2 c)
{
    glBegin(GL_TRIANGLES);
    glVertex2fv(a);
    glVertex2fv(b);
    glVertex2fv(c);
    glEnd();
}

// Implementation of the Sierpinski gasket by triangle subdivision
// using vertex numbers.
void divide_triangle(Point2 a, Point2 b, Point2 c, int m)
{
    Point2 v0, v1, v2;
    int j;
    if (m>0) {
        for(j=0; j<2; j++) 
            v0[j]=(a[j]+b[j])/2;
        for(j=0; j<2; j++) 
            v1[j]=(a[j]+c[j])/2;
        for(j=0; j<2; j++) 
            v2[j]=(b[j]+c[j])/2;
        divide_triangle(a, v0, v1, m-1);
        divide_triangle(c, v1, v2, m-1);
        divide_triangle(b, v2, v0, m-1);
    }
    else
        triangle(a,b,c); // draw triangle at end of recursion 
}


// Implementation of the Sierpinski "carpet".
void carpet(Point2 start, float width, int m)
{
    // To be implemented by the student
}