//Sinusoidal easing
//Jeff Thompson | 2019/20 | jeffreythompson.org

let SINUSOIDAL =  5;

// when the easing is applied (start, end, or both)
let IN =   0;
let OUT =  1;
let BOTH = 2;

// a map() replacement that allows for specifying easing curves
// with arbitrary exponents
function map2(value, start1, stop1, start2, stop2, type, when) {
  let b = start2;
  let c = stop2 - start2;
  let t = value - start1;
  let d = stop1 - start1;
  let p = 0.5;
  
  switch (type) {

  case SINUSOIDAL:
    if (when === IN) {
      return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
    } 
    else if (when === OUT) {
      return c * Math.sin(t/d * (Math.PI/2)) + b;
    } 
    else if (when === BOTH) {
      return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
    }
    break;
  };
  
  return 0;
}