重力ダンス

const G = 1;

​

const objs = [

  [50,130,0,0,1],

  [150,230,0,0,1],

  [360,330,0,0,1],

  [240,260,0,0,1],

  [180,30,0,0,1],

];

​

var add = function(x,y,vx,vy,mass){

    objs.push([x,y,vx,vy,mass]);

}

​

const step = function(dt){

    //console.log(dt);

    for(let i = 0; i < objs.length; i++){

        for(let j = i+1; j < objs.length; j++){

            //bidirectional

            const o1 = objs[i];

            const o2 = objs[j];

            const dx = o2[0]-o1[0];

            const dy = o2[1]-o1[1];

            const dist2 = dx*dx+dy*dy;

            const dist = Math.sqrt(dist2);

            const rr = 10+10;

            if(dist < rr){

                const alphal = ((o1[2]-o2[2])*dx+(o1[3]-o2[3])*dy)/(dx*dx+dy*dy)/2*0.95;

                const alphax = alphal*dx;

                const alphay = alphal*dy;

​

                o1[2] = o1[2]-2*alphax;

                o1[3] = o1[3]-2*alphay;

                o2[2] = o2[2]+2*alphax;

                o2[3] = o2[3]+2*alphay;

                //move them away on the collision axis

                const penetration = (rr-dist)/dist;

                const xm = dx*penetration/2;

                const ym = dy*penetration/2;

                o1[0] += -xm;

                o1[1] += -ym;

                o2[0] += xm;

                o2[1] += ym;

                continue;

            }

​

            const acc1 = G*o2[4]/dist2;

            const acc1x = acc1*(dx/dist);

            const acc1y = acc1*(dy/dist);

            o1[2]+= acc1x*dt;

            o1[3]+= acc1y*dt;

​

            const acc2 = G*o1[4]/dist2;

            const acc2x = acc2*(-dx/dist);

            const acc2y = acc2*(-dy/dist);

            o2[2]+= acc2x*dt;

            o2[3]+= acc2y*dt;

        }

    }

    for(let i = 0; i < objs.length; i++){

        const o = objs[i];

        o[0] += o[2]*dt;

        o[1] += o[3]*dt;

    }

};

​

function setup() {

  createCanvas(400, 400);

  stroke(0,0,0,0);

  fill(0,0,0);

}

​

function draw() {

  background(255);

  const steps = 10;

  for(let i = 0; i < steps; i++){

    step(1);

  }

  for(let i = 0; i < objs.length; i++){

    const o = objs[i];

    circle(o[0],o[1],20);

  }

}