int pts = 4; 
  float angle = 0;
  float radius = 99;
  float cylinderLength = 95;
  
  //vertices
  PVector vertices[][];
  boolean isPyramid = false;
  
  float angleInc;
  
  void setup(){
    size(640, 360, P3D);
    noStroke();
    angleInc = PI/300.0;
  }
  
  void draw(){
    background(170, 95, 95);
    lights();
    fill(255, 200, 200);
    translate(width/2, height/2);
    rotateX(frameCount * angleInc);
    rotateY(frameCount * angleInc);
    rotateZ(frameCount * angleInc);
  
    // initialize vertex arrays
    vertices = new PVector[2][pts+1];
  
    // fill arrays
    for (int i = 0; i < 2; i++){
      angle = 0;
      for(int j = 0; j <= pts; j++){
        vertices[i][j] = new PVector();
        if (isPyramid){
          if (i==1){
            vertices[i][j].x = 0;
            vertices[i][j].y = 0;
          }
          else {
            vertices[i][j].x = cos(radians(angle)) * radius;
            vertices[i][j].y = sin(radians(angle)) * radius;
          }
        } 
        else {
          vertices[i][j].x = cos(radians(angle)) * radius;
          vertices[i][j].y = sin(radians(angle)) * radius;
        }
        vertices[i][j].z = cylinderLength; 
        // the .0 after the 360 is critical
        angle += 360.0/pts;
      }
      cylinderLength *= -1;
    }
  
    // draw cylinder tube
    beginShape(QUAD_STRIP);
    for(int j = 0; j <= pts; j++){
      vertex(vertices[0][j].x, vertices[0][j].y, vertices[0][j].z);
      vertex(vertices[1][j].x, vertices[1][j].y, vertices[1][j].z);
    }
    endShape();
  
    //draw cylinder ends
    for (int i = 0; i < 2; i++){
      beginShape();
      for(int j = 0; j < pts; j++){
        vertex(vertices[i][j].x, vertices[i][j].y, vertices[i][j].z);
      }
      endShape(CLOSE);
    }
  }
  
  /*
   up/down arrow keys control
   polygon detail.
   */
  void keyPressed(){
    if(key == CODED) { 
      // pts
      if (keyCode == UP) { 
        if (pts < 90){
          pts++;
        } 
      } 
      else if (keyCode == DOWN) { 
        if (pts > 4){
          pts--;
        }
      } 
    }
    if (key =='p'){
      if (isPyramid){
        isPyramid = false;
      } 
      else {
        isPyramid = true;
      }
    }
  }