/*

​

my helper thing for https://www.codingame.com/ide/puzzle/search-race

​

​

im age8ugag9a438ugh9i4a3gh93ayhgpahygpa4gh dont understand a thing

reading to do https://math.stackexchange.com/a/2587852

​

*/

​

const cp_radius = 50;

const cp_coords = [[50,50],[300,300],[100,300]]

const checkpoints = [];

​

var ti = 0;

var car;

var speed;

var turnLerp;

function setup() {

  createCanvas(400, 400);

  angleMode(DEGREES);

  turnLerp = createSlider(0,100,20);

  for (coords of cp_coords) {

    [cx, cy] = coords;

    checkpoints.push(createVector(cx,cy));

  }

  car = createVector(200,200);

  speed = createVector(1,1);

}

​

function draw() {

  background(220);

  // draw checkpoints

  stroke(0);

  strokeWeight(1);

  for (cp of checkpoints){

    point(cp.x, cp.y);

    fill(0,0,100,30);

    circle(cp.x,cp.y,cp_radius*2);

  }

  // get target checkpoint

  var tc = checkpoints[ti];

  var tn = checkpoints[ (ti+1) % checkpoints.length]

    if (car.dist(tc) < cp_radius){

      ti = ((ti+1) % checkpoints.length);

      tc = checkpoints[ti];

    }

  var target_diff = createVector(tc.x - car.x, tc.y-car.y);

  var angle_to_cp = speed.angleBetween(target_diff);

  // how to limit this rotation speed?  aka

  // how to write this without the lerp i guess

  var lerpitylerplerp = map(turnLerp.value(), 0,100,0.5,0.999);

  speed.rotate(lerp(angle_to_cp, 0, lerpitylerplerp));

  car.add(speed);

  strokeWeight(10);

  point(car.x, car.y);

  strokeWeight(0);

  fill(0);

  text(`higher value is less turny ${map(turnLerp.value(), 0,100,0.5,0.999).toFixed(2)}`,5,height-5);

  stroke(255,255,0,110);

  strokeWeight(1);

  line(car.x, car.y, tc.x,tc.y);

  line(tc.x,tc.y ,tn.x, tn.y);

  var next_angle = 

      // nevermind this. i dont get it .atan2(tn.y - car.y, tn.x - car.x) - atan2(tc.y - car.y, tc.x - car.x);

  // law of cosines

  // p1 = the current checkpoint

  //https://stackoverflow.com/a/1211243/6934388

      // i dont get this either but it works

      acos( 

    ((tc.dist(car)*tc.dist(car)) + 

    (tc.dist(tn)*tc.dist(tn)) - (car.dist(tn)*car.dist(tn) )) 

    / (2 * tc.dist(car) * tc.dist(tn)) 

  );

  text(`${next_angle.toFixed(1)}`, tc.x, tc.y);

  push();

  translate(car.x,car.y);

  stroke('red')

  strokeWeight(2);

  line(0,0, speed.x*25, speed.y*25);

  pop();

​

}