module.exports = angle

var fromValues = require('./fromValues')
var normalize = require('./normalize')
var dot = require('./dot')

/**
 * Get the angle between two 3D vectors
 * @param {vec3} a The first operand
 * @param {vec3} b The second operand
 * @returns {Number} The angle in radians
 */
function angle(a, b) {
    var tempA = fromValues(a[0], a[1], a[2])
    var tempB = fromValues(b[0], b[1], b[2])
 
    normalize(tempA, tempA)
    normalize(tempB, tempB)
 
    var cosine = dot(tempA, tempB)

    if(cosine > 1.0){
        return 0
    } else {
        return Math.acos(cosine)
    }     
}