lerp = (out, a, b, t) => {
  out[0] = a[0] + t * (b[0] - a[0])
  out[1] = a[1] + t * (b[1] - a[1])
  out[2] = a[2] + t * (b[2] - a[2])
  return out
}
Performs a linear interpolation between two vectors.

@param {vec3} out - receiving vector
@param {vec3} a - first operand
@param {vec3} b - second operand
@param {Number} t - interpolant (0.0 to 1.0) applied between the two inputs
@returns {vec3} out
@alias module:modeling/maths/vec3.lerp