gistfile1.js

function toIndice(vec, gw) {
    return ((vec.y) * gw + vec.x);
}

function isUnique(array) {
    var uniques = _.uniq(array);

    return array.length === uniques.length;
};

var i, vectors = [], indices = [];
for (i = 0; i < 1000; i += 1) {
    vectors.push(new Vector(0, 0, 0));
}

var j;
for (j = 0; j < vectors.length; j += 1) {
    vectors[j].x = j;
    indices.push(toIndice(vectors[j], 10));
}

var k;
for (k = 0; k < vectors.length; k += 1) {
    vectors[k].y = k;
    indices.push(toIndice(vectors[k], 10));
}

console.log(isUnique(indices));
=> false