text: /**
   * Copyright (c) 2015-present, Facebook, Inc.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   *
   * @flow
   */
  
  'use strict';
  
  type SpringConfigType = {
    stiffness: number,
    damping: number
  };
  
  function stiffnessFromOrigamiValue(oValue) {
    return (oValue - 30) * 3.62 + 194;
  }
  
  function dampingFromOrigamiValue(oValue) {
    return (oValue - 8) * 3 + 25;
  }
  
  function fromOrigamiTensionAndFriction(tension: number, friction: number): SpringConfigType {
    return {
      stiffness: stiffnessFromOrigamiValue(tension),
      damping: dampingFromOrigamiValue(friction)
    };
  }
  
  function fromBouncinessAndSpeed(bounciness: number, speed: number): SpringConfigType {
    function normalize(value, startValue, endValue) {
      return (value - startValue) / (endValue - startValue);
    }
  
    function projectNormal(n, start, end) {
      return start + n * (end - start);
    }
  
    function linearInterpolation(t, start, end) {
      return t * end + (1 - t) * start;
    }
  
    function quadraticOutInterpolation(t, start, end) {
      return linearInterpolation(2 * t - t * t, start, end);
    }
  
    function b3Friction1(x) {
      return 0.0007 * Math.pow(x, 3) - 0.031 * Math.pow(x, 2) + 0.64 * x + 1.28;
    }
  
    function b3Friction2(x) {
      return 0.000044 * Math.pow(x, 3) - 0.006 * Math.pow(x, 2) + 0.36 * x + 2;
    }
  
    function b3Friction3(x) {
      return 0.00000045 * Math.pow(x, 3) - 0.000332 * Math.pow(x, 2) + 0.1078 * x + 5.84;
    }
  
    function b3Nobounce(tension) {
      if (tension <= 18) {
        return b3Friction1(tension);
      } else if (tension > 18 && tension <= 44) {
        return b3Friction2(tension);
      } else {
        return b3Friction3(tension);
      }
    }
  
    var b = normalize(bounciness / 1.7, 0, 20);
    b = projectNormal(b, 0, 0.8);
    var s = normalize(speed / 1.7, 0, 20);
    var bouncyTension = projectNormal(s, 0.5, 200);
    var bouncyFriction = quadraticOutInterpolation(b, b3Nobounce(bouncyTension), 0.01);
  
    return {
      stiffness: stiffnessFromOrigamiValue(bouncyTension),
      damping: dampingFromOrigamiValue(bouncyFriction)
    };
  }
  
  module.exports = {
    fromOrigamiTensionAndFriction,
    fromBouncinessAndSpeed
  };
  