Player is falling from the level..

Hi guys i have a problem … my player is falling from the lvl . I have a box collider on player as well as on the lvl … and also i don’t want to add rigibody to the player thats why i added a gravity script to the player …but it is falling through the lvl…and this is my gravity script…

var velocity: Vector3 = Vector3(5, 5, 0);
var gravity: float = 9.8;
function Update(){ 
// apply gravity 
 velocity.y -= gravity * Time.deltaTime; 
// calculate new position
 transform.position += velocity * Time.deltaTime;

Without a rigidbody, movement with Physics colliders will not work. Everything that needs movement in the realm of Physics needs one, no way around it. If you really want to avoid physics, don’t use a collider at all, but stop the transform position to decrease any further when it reached the floor.