/* 
Part of the ReCode Project (http://recodeproject.com)
Based on "Untitled" by Georg Nees
Originally published in "Computer Graphics and Art" v1n2, 1976
Copyright (c) 2013 Thomas Crevoisier - OSI/MIT license (http://recodeproject/license).
*/

/* @pjs pauseOnBlur="true"; */

void setup() {
  size(800, 800, P3D);
  smooth();
  stroke(255);
  noFill();
}

void draw() {
  background(0);  

  pushMatrix();
  translate(width/2, 10, 0);
  branch(10, 60);
  popMatrix();
}

void drawPyramid(float xS, float yS, float zS, float h) {

  float x1, y1, z1, x2, y2, z2, x3, y3, z3;
  //Calculate coordinate of the other points of the pyramid, having the height h of this pyramid and coordinates of the highest point
  x1 = xS;
  y1 = yS + h;
  z1 = zS + h/sqrt(2);

  x2 = xS + h*sqrt(6)/4;
  y2 = yS + h;
  z2 = zS - h*sqrt(2)/4;

  x3 = xS - h*sqrt(6)/4;
  y3 = yS + h;
  z3 = zS - h*sqrt(2)/4;

  //Draw the four faces of the pyramids
  beginShape();
  vertex(xS, yS, zS);
  vertex(x1, y1, z1);
  vertex(x2, y2, z2);
  endShape(CLOSE);
  beginShape();
  vertex(xS, yS, zS);
  vertex(x2, y2, z2);
  vertex(x3, y3, z3);
  endShape(CLOSE);
  beginShape();
  vertex(xS, yS, zS);
  vertex(x3, y3, z3);
  vertex(x1, y1, z1);
  endShape(CLOSE);
  beginShape();
  vertex(x1, y1, z1);
  vertex(x2, y2, z2);
  vertex(x3, y3, z3);
  endShape(CLOSE);
}

void branch(int N, float h) {
  N -= 1;

  if (N>0) {
    //Calculate the next three points which are the other points of the pyramids
    float x1, y1, z1, x2, y2, z2, x3, y3, z3;
    x1 = 0;
    y1 = h;
    z1 = h/sqrt(2);

    x2 = h*sqrt(6)/4;
    y2 = h;
    z2 = -h*sqrt(2)/4;

    x3 = -h*sqrt(6)/4;
    y3 = h;
    z3 = -h*sqrt(2)/4;
    
    //Use the recursive function to draw a pyramid for the three points for which we calculate coordinates
    pushMatrix();
    drawPyramid(0, 0, 0, h);
    translate(x1, y1, z1);
    branch(N, h);
    popMatrix();

    pushMatrix();
    drawPyramid(0, 0, 0, h);
    translate(x2, y2, z2);
    branch(N, h);
    popMatrix();

    pushMatrix();
    drawPyramid(0, 0, 0, h);
    translate(x3, y3, z3);
    branch(N, h);
    popMatrix();
  }
}