how to go through platform like bananakong?

hey guys… i need some help… i have tired to try this function… i want to make platformer sidescroller game like bananakong… i can to make character controller… but really tired to try some function like banana kong. i want to make player can go through to platform when player has jump. like banana kong. when the character under platform, and character jump collider istrigger, but when the character has go through… collider has without istrigger?
like these :

alt text

i have to try using this code

void OnCollisionEnter2D(Collision2D coll) {
if (coll.gameObject.tag == “Player” &&!collider2D.isTrigger)
collider2D.isTrigger = true;
}

void OnTriggerEnter2D(Collider2D other){
	if(other.gameObject.tag == "canGoThrough" ){
		collider2D.isTrigger = false;
	}
}

and this my youtube link video for my problem, when i use code like there…

http://youtu.be/TdEaBgj4cTI!

i hope someone can help me??
thanks

I would try checking if the players velocity.y > 0. then make it’s collider a trigger. In C#, it could be one line in the players update. although you might only want to check when the player is not grounded.

gameObject.collider2D.isTrigger = (gameObject.rigidbody.velocity.y > 0) ? true : false ;