text: import * as glMatrix from "./common.js";
  
  /**
   * 4 Dimensional Vector
   * @module vec4
   */
  
  /**
   * Creates a new, empty vec4
   *
   * @returns {vec4} a new 4D vector
   */
  export function create() {
    let out = new glMatrix.ARRAY_TYPE(4);
    if(glMatrix.ARRAY_TYPE != Float32Array) {
      out[0] = 0;
      out[1] = 0;
      out[2] = 0;
      out[3] = 0;
    }
    return out;
  }
  
  /**
   * Creates a new vec4 initialized with values from an existing vector
   *
   * @param {vec4} a vector to clone
   * @returns {vec4} a new 4D vector
   */
  export function clone(a) {
    let out = new glMatrix.ARRAY_TYPE(4);
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    return out;
  }
  
  /**
   * Creates a new vec4 initialized with the given values
   *
   * @param {Number} x X component
   * @param {Number} y Y component
   * @param {Number} z Z component
   * @param {Number} w W component
   * @returns {vec4} a new 4D vector
   */
  export function fromValues(x, y, z, w) {
    let out = new glMatrix.ARRAY_TYPE(4);
    out[0] = x;
    out[1] = y;
    out[2] = z;
    out[3] = w;
    return out;
  }
  
  /**
   * Copy the values from one vec4 to another
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the source vector
   * @returns {vec4} out
   */
  export function copy(out, a) {
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    return out;
  }
  
  /**
   * Set the components of a vec4 to the given values
   *
   * @param {vec4} out the receiving vector
   * @param {Number} x X component
   * @param {Number} y Y component
   * @param {Number} z Z component
   * @param {Number} w W component
   * @returns {vec4} out
   */
  export function set(out, x, y, z, w) {
    out[0] = x;
    out[1] = y;
    out[2] = z;
    out[3] = w;
    return out;
  }
  
  /**
   * Adds two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function add(out, a, b) {
    out[0] = a[0] + b[0];
    out[1] = a[1] + b[1];
    out[2] = a[2] + b[2];
    out[3] = a[3] + b[3];
    return out;
  }
  
  /**
   * Subtracts vector b from vector a
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function subtract(out, a, b) {
    out[0] = a[0] - b[0];
    out[1] = a[1] - b[1];
    out[2] = a[2] - b[2];
    out[3] = a[3] - b[3];
    return out;
  }
  
  /**
   * Multiplies two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function multiply(out, a, b) {
    out[0] = a[0] * b[0];
    out[1] = a[1] * b[1];
    out[2] = a[2] * b[2];
    out[3] = a[3] * b[3];
    return out;
  }
  
  /**
   * Divides two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function divide(out, a, b) {
    out[0] = a[0] / b[0];
    out[1] = a[1] / b[1];
    out[2] = a[2] / b[2];
    out[3] = a[3] / b[3];
    return out;
  }
  
  /**
   * Math.ceil the components of a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to ceil
   * @returns {vec4} out
   */
  export function ceil(out, a) {
    out[0] = Math.ceil(a[0]);
    out[1] = Math.ceil(a[1]);
    out[2] = Math.ceil(a[2]);
    out[3] = Math.ceil(a[3]);
    return out;
  }
  
  /**
   * Math.floor the components of a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to floor
   * @returns {vec4} out
   */
  export function floor(out, a) {
    out[0] = Math.floor(a[0]);
    out[1] = Math.floor(a[1]);
    out[2] = Math.floor(a[2]);
    out[3] = Math.floor(a[3]);
    return out;
  }
  
  /**
   * Returns the minimum of two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function min(out, a, b) {
    out[0] = Math.min(a[0], b[0]);
    out[1] = Math.min(a[1], b[1]);
    out[2] = Math.min(a[2], b[2]);
    out[3] = Math.min(a[3], b[3]);
    return out;
  }
  
  /**
   * Returns the maximum of two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {vec4} out
   */
  export function max(out, a, b) {
    out[0] = Math.max(a[0], b[0]);
    out[1] = Math.max(a[1], b[1]);
    out[2] = Math.max(a[2], b[2]);
    out[3] = Math.max(a[3], b[3]);
    return out;
  }
  
  /**
   * Math.round the components of a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to round
   * @returns {vec4} out
   */
  export function round(out, a) {
    out[0] = Math.round(a[0]);
    out[1] = Math.round(a[1]);
    out[2] = Math.round(a[2]);
    out[3] = Math.round(a[3]);
    return out;
  }
  
  /**
   * Scales a vec4 by a scalar number
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the vector to scale
   * @param {Number} b amount to scale the vector by
   * @returns {vec4} out
   */
  export function scale(out, a, b) {
    out[0] = a[0] * b;
    out[1] = a[1] * b;
    out[2] = a[2] * b;
    out[3] = a[3] * b;
    return out;
  }
  
  /**
   * Adds two vec4's after scaling the second operand by a scalar value
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @param {Number} scale the amount to scale b by before adding
   * @returns {vec4} out
   */
  export function scaleAndAdd(out, a, b, scale) {
    out[0] = a[0] + (b[0] * scale);
    out[1] = a[1] + (b[1] * scale);
    out[2] = a[2] + (b[2] * scale);
    out[3] = a[3] + (b[3] * scale);
    return out;
  }
  
  /**
   * Calculates the euclidian distance between two vec4's
   *
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {Number} distance between a and b
   */
  export function distance(a, b) {
    let x = b[0] - a[0];
    let y = b[1] - a[1];
    let z = b[2] - a[2];
    let w = b[3] - a[3];
    return Math.hypot(x, y, z, w);
  }
  
  /**
   * Calculates the squared euclidian distance between two vec4's
   *
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {Number} squared distance between a and b
   */
  export function squaredDistance(a, b) {
    let x = b[0] - a[0];
    let y = b[1] - a[1];
    let z = b[2] - a[2];
    let w = b[3] - a[3];
    return x*x + y*y + z*z + w*w;
  }
  
  /**
   * Calculates the length of a vec4
   *
   * @param {vec4} a vector to calculate length of
   * @returns {Number} length of a
   */
  export function length(a) {
    let x = a[0];
    let y = a[1];
    let z = a[2];
    let w = a[3];
    return Math.hypot(x, y, z, w);
  }
  
  /**
   * Calculates the squared length of a vec4
   *
   * @param {vec4} a vector to calculate squared length of
   * @returns {Number} squared length of a
   */
  export function squaredLength(a) {
    let x = a[0];
    let y = a[1];
    let z = a[2];
    let w = a[3];
    return x*x + y*y + z*z + w*w;
  }
  
  /**
   * Negates the components of a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to negate
   * @returns {vec4} out
   */
  export function negate(out, a) {
    out[0] = -a[0];
    out[1] = -a[1];
    out[2] = -a[2];
    out[3] = -a[3];
    return out;
  }
  
  /**
   * Returns the inverse of the components of a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to invert
   * @returns {vec4} out
   */
  export function inverse(out, a) {
    out[0] = 1.0 / a[0];
    out[1] = 1.0 / a[1];
    out[2] = 1.0 / a[2];
    out[3] = 1.0 / a[3];
    return out;
  }
  
  /**
   * Normalize a vec4
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a vector to normalize
   * @returns {vec4} out
   */
  export function normalize(out, a) {
    let x = a[0];
    let y = a[1];
    let z = a[2];
    let w = a[3];
    let len = x*x + y*y + z*z + w*w;
    if (len > 0) {
      len = 1 / Math.sqrt(len);
    }
    out[0] = x * len;
    out[1] = y * len;
    out[2] = z * len;
    out[3] = w * len;
    return out;
  }
  
  /**
   * Calculates the dot product of two vec4's
   *
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @returns {Number} dot product of a and b
   */
  export function dot(a, b) {
    return a[0] * b[0] + a[1] * b[1] + a[2] * b[2] + a[3] * b[3];
  }
  
  /**
   * Returns the cross-product of three vectors in a 4-dimensional space
   *
   * @param {vec4} result the receiving vector
   * @param {vec4} U the first vector
   * @param {vec4} V the second vector
   * @param {vec4} W the third vector
   * @returns {vec4} result
   */
  export function cross (out, u, v, w) {
      let A = (v[0] * w[1]) - (v[1] * w[0]),
          B = (v[0] * w[2]) - (v[2] * w[0]),
          C = (v[0] * w[3]) - (v[3] * w[0]),
          D = (v[1] * w[2]) - (v[2] * w[1]),
          E = (v[1] * w[3]) - (v[3] * w[1]),
          F = (v[2] * w[3]) - (v[3] * w[2]);
      let G = u[0];
      let H = u[1];
      let I = u[2];
      let J = u[3];
  
      out[0] = (H * F) - (I * E) + (J * D);
      out[1] = -(G * F) + (I * C) - (J * B);
      out[2] = (G * E) - (H * C) + (J * A);
      out[3] = -(G * D) + (H * B) - (I * A);
  
      return out;
  };
  
  /**
   * Performs a linear interpolation between two vec4's
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the first operand
   * @param {vec4} b the second operand
   * @param {Number} t interpolation amount, in the range [0-1], between the two inputs
   * @returns {vec4} out
   */
  export function lerp(out, a, b, t) {
    let ax = a[0];
    let ay = a[1];
    let az = a[2];
    let aw = a[3];
    out[0] = ax + t * (b[0] - ax);
    out[1] = ay + t * (b[1] - ay);
    out[2] = az + t * (b[2] - az);
    out[3] = aw + t * (b[3] - aw);
    return out;
  }
  
  /**
   * Generates a random vector with the given scale
   *
   * @param {vec4} out the receiving vector
   * @param {Number} [scale] Length of the resulting vector. If ommitted, a unit vector will be returned
   * @returns {vec4} out
   */
  export function random(out, scale) {
    scale = scale || 1.0;
  
    // Marsaglia, George. Choosing a Point from the Surface of a
    // Sphere. Ann. Math. Statist. 43 (1972), no. 2, 645--646.
    // http://projecteuclid.org/euclid.aoms/1177692644;
    var v1, v2, v3, v4;
    var s1, s2;
    do {
      v1 = glMatrix.RANDOM() * 2 - 1;
      v2 = glMatrix.RANDOM() * 2 - 1;
      s1 = v1 * v1 + v2 * v2;
    } while (s1 >= 1);
    do {
      v3 = glMatrix.RANDOM() * 2 - 1;
      v4 = glMatrix.RANDOM() * 2 - 1;
      s2 = v3 * v3 + v4 * v4;
    } while (s2 >= 1);
  
    var d = Math.sqrt((1 - s1) / s2);
    out[0] = scale * v1;
    out[1] = scale * v2;
    out[2] = scale * v3 * d;
    out[3] = scale * v4 * d;
    return out;
  }
  
  /**
   * Transforms the vec4 with a mat4.
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the vector to transform
   * @param {mat4} m matrix to transform with
   * @returns {vec4} out
   */
  export function transformMat4(out, a, m) {
    let x = a[0], y = a[1], z = a[2], w = a[3];
    out[0] = m[0] * x + m[4] * y + m[8] * z + m[12] * w;
    out[1] = m[1] * x + m[5] * y + m[9] * z + m[13] * w;
    out[2] = m[2] * x + m[6] * y + m[10] * z + m[14] * w;
    out[3] = m[3] * x + m[7] * y + m[11] * z + m[15] * w;
    return out;
  }
  
  /**
   * Transforms the vec4 with a quat
   *
   * @param {vec4} out the receiving vector
   * @param {vec4} a the vector to transform
   * @param {quat} q quaternion to transform with
   * @returns {vec4} out
   */
  export function transformQuat(out, a, q) {
    let x = a[0], y = a[1], z = a[2];
    let qx = q[0], qy = q[1], qz = q[2], qw = q[3];
  
    // calculate quat * vec
    let ix = qw * x + qy * z - qz * y;
    let iy = qw * y + qz * x - qx * z;
    let iz = qw * z + qx * y - qy * x;
    let iw = -qx * x - qy * y - qz * z;
  
    // calculate result * inverse quat
    out[0] = ix * qw + iw * -qx + iy * -qz - iz * -qy;
    out[1] = iy * qw + iw * -qy + iz * -qx - ix * -qz;
    out[2] = iz * qw + iw * -qz + ix * -qy - iy * -qx;
    out[3] = a[3];
    return out;
  }
  
  /**
   * Set the components of a vec4 to zero
   *
   * @param {vec4} out the receiving vector
   * @returns {vec4} out
   */
  export function zero(out) {
    out[0] = 0.0;
    out[1] = 0.0;
    out[2] = 0.0;
    out[3] = 0.0;
    return out;
  }
  
  /**
   * Returns a string representation of a vector
   *
   * @param {vec4} a vector to represent as a string
   * @returns {String} string representation of the vector
   */
  export function str(a) {
    return 'vec4(' + a[0] + ', ' + a[1] + ', ' + a[2] + ', ' + a[3] + ')';
  }
  
  /**
   * Returns whether or not the vectors have exactly the same elements in the same position (when compared with ===)
   *
   * @param {vec4} a The first vector.
   * @param {vec4} b The second vector.
   * @returns {Boolean} True if the vectors are equal, false otherwise.
   */
  export function exactEquals(a, b) {
    return a[0] === b[0] && a[1] === b[1] && a[2] === b[2] && a[3] === b[3];
  }
  
  /**
   * Returns whether or not the vectors have approximately the same elements in the same position.
   *
   * @param {vec4} a The first vector.
   * @param {vec4} b The second vector.
   * @returns {Boolean} True if the vectors are equal, false otherwise.
   */
  export function equals(a, b) {
    let a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3];
    let b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3];
    return (Math.abs(a0 - b0) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a0), Math.abs(b0)) &&
            Math.abs(a1 - b1) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a1), Math.abs(b1)) &&
            Math.abs(a2 - b2) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a2), Math.abs(b2)) &&
            Math.abs(a3 - b3) <= glMatrix.EPSILON*Math.max(1.0, Math.abs(a3), Math.abs(b3)));
  }
  
  /**
   * Alias for {@link vec4.subtract}
   * @function
   */
  export const sub = subtract;
  
  /**
   * Alias for {@link vec4.multiply}
   * @function
   */
  export const mul = multiply;
  
  /**
   * Alias for {@link vec4.divide}
   * @function
   */
  export const div = divide;
  
  /**
   * Alias for {@link vec4.distance}
   * @function
   */
  export const dist = distance;
  
  /**
   * Alias for {@link vec4.squaredDistance}
   * @function
   */
  export const sqrDist = squaredDistance;
  
  /**
   * Alias for {@link vec4.length}
   * @function
   */
  export const len = length;
  
  /**
   * Alias for {@link vec4.squaredLength}
   * @function
   */
  export const sqrLen = squaredLength;
  
  /**
   * Perform some operation over an array of vec4s.
   *
   * @param {Array} a the array of vectors to iterate over
   * @param {Number} stride Number of elements between the start of each vec4. If 0 assumes tightly packed
   * @param {Number} offset Number of elements to skip at the beginning of the array
   * @param {Number} count Number of vec4s to iterate over. If 0 iterates over entire array
   * @param {Function} fn Function to call for each vector in the array
   * @param {Object} [arg] additional argument to pass to fn
   * @returns {Array} a
   * @function
   */
  export const forEach = (function() {
    let vec = create();
  
    return function(a, stride, offset, count, fn, arg) {
      let i, l;
      if(!stride) {
        stride = 4;
      }
  
      if(!offset) {
        offset = 0;
      }
  
      if(count) {
        l = Math.min((count * stride) + offset, a.length);
      } else {
        l = a.length;
      }
  
      for(i = offset; i < l; i += stride) {
        vec[0] = a[i]; vec[1] = a[i+1]; vec[2] = a[i+2]; vec[3] = a[i+3];
        fn(vec, vec, arg);
        a[i] = vec[0]; a[i+1] = vec[1]; a[i+2] = vec[2]; a[i+3] = vec[3];
      }
  
      return a;
    };
  })();
  