gistfile1.js

RunnerPlayer.prototype.isOnTheGround = function() {
    var from = this.getPosition(),
        to = [from[0], from[1] - 1, from[2]];

    var resultCallback = new Ammo.AllHitsRayResultCallback(from, to);
    this.game.context.physics.dynamicsWorld.rayTest(from, to, resultCallback);

    console.log(resultCallback.hasHit());
};