let x1_,y1_,x2_,y2_,l1_,l2_,p1_,p2_,m1_,m2_,theta1_,theta2_,theta1vel_,theta2vel_,theta1Acc_,theta2Acc_;

const g = 2;

​

let x2p,y2p;

let x2p_,y2p_;

​

function setup() {

  createCanvas(400, 400);

  l1 = 100;

  l2 = 100;

  m1 = 10;

  m2 = 10;

  theta1 = PI/2;

  theta2 = PI/2 + 16 * PI/180;

  theta1Vel = 0;

  theta2Vel = 0;

  l1_ = 100;

  l2_ = 100;

  m1_ = 10;

  m2_ = 10;

  theta1_ = PI/2;

  theta2_ = PI/2 + 18 * PI/180;

  theta1Vel_ = 0;

  theta2Vel_ = 0;

  //background(220);

  //frameRate(30);

}

​

function draw() {

  background(220);

  let nom = -g * (2 * m1 + m2)*sin(theta1) - m2*g*sin(theta1 - 2*theta2) - 2*sin(theta1 - theta2)*m2*(theta2Vel ** 2 * l2 + theta1Vel**2 * l1* cos(theta1 - theta2));

  let den = l1*(2*m1 + m2 - m2*cos(2*theta1 - 2*theta2));

  theta1Acc = nom/den;

  nom = 2*sin(theta1 - theta2) * (theta1Vel**2 * l1 * (m1 + m2) + g*(m1 + m2) * cos(theta1) + theta2Vel**2 *  l2 * m2 * cos(theta1 - theta2))

  den = l2*(2*m1 + m2 - m2*cos(2*theta1 - 2*theta2))

  theta2Acc = nom/den;

  x1 = l1*sin(theta1);

  y1 = l1*cos(theta1);

  x2 = x1 + l2*sin(theta2);

  y2 = y1 + l2*cos(theta1);

  if(x2p == null){

    x2p = x1 + l2*sin(theta2);

    y2p = y1 + l2*cos(theta1);

  }

  // stroke(0,0,0,10);

  translate(width/2,height/2);

  //fill(100,100,100,10);

  stroke(0);

  fill(100)

  line(0,0,x1,y1);

  circle(x1,y1,m1);

  line(x1,y1,x2,y2);

  circle(x2,y2,m2);

  //stroke(0);

  //line(x2p,y2p,x2,y2);

  theta1Vel += theta1Acc;

  theta2Vel += theta2Acc;

  // theta1Vel *= 0.99;

  // theta2Vel *= 0.99;

  theta1 += theta1Vel;

  theta2 += theta2Vel;

  x2p = x2;

  y2p = y2;

  //------\\

  nom = -g * (2 * m1_ + m2_)*sin(theta1_) - m2_*g*sin(theta1_ - 2*theta2_) - 2*sin(theta1_ - theta2_)*m2_*(theta2Vel_ ** 2 * l2_ + theta1Vel_**2 * l1_* cos(theta1_ - theta2_));

  den = l1_*(2*m1_ + m2_ - m2_*cos(2*theta1_ - 2*theta2_));

  theta1Acc_ = nom/den;

  nom = 2*sin(theta1_ - theta2_) * (theta1Vel_**2 * l1_ * (m1_ + m2_) + g*(m1_ + m2_) * cos(theta1_) + theta2Vel_**2 *  l2_ * m2_ * cos(theta1_ - theta2_))

  den = l2_*(2*m1_ + m2_ - m2_*cos(2*theta1_ - 2*theta2_))

  theta2Acc_ = nom/den;

  x1_ = l1_*sin(theta1_);

  y1_ = l1_*cos(theta1_);

  x2_ = x1_ + l2_*sin(theta2_);

  y2_ = y1_ + l2_*cos(theta1_);

  if(x2p_ == null){

    x2p_ = x1_ + l2_*sin(theta2_);

    y2p_ = y1_ + l2_*cos(theta1_);

  }

  // stroke(0,0,0,10);

  //translate(width/2,height/2);

  // fill(100,100,100,10);

  stroke(0);

  fill(255,0,0);

  line(0,0,x1_,y1_);

  circle(x1_,y1_,m1_);

  line(x1_,y1_,x2_,y2_);

  circle(x2_,y2_,m2_);

  //stroke(255,0,0);

  //line(x2p_,y2p_,x2_,y2_);

  theta1Vel_ += theta1Acc_;

  theta2Vel_ += theta2Acc_;

//   theta1Vel_ *= 0.99;

//   theta2Vel_ *= 0.99;

  theta1_ += theta1Vel_;

  theta2_ += theta2Vel_;

  x2p_ = x2_;

  y2p_ = y2_;

}

​