2D Collision on specific area of a sprite

I am new to unity. Just started reading some tutorials yesterday. I'm trying to make a certain object in the game have a collision point on a certain area of it (ex: the twigs of a tree). But have no idea how to do this. Help please?

 

Hi! What you're looking for are called colliders, in particular colliders2D. Colliders are components you add to your game objects. There are several types of colliders and each one can be edited by using the edit collider button, present in the Explorer. Using this functionality you can adjust the collision points at your will

 

so its ok to remove the Rigid Body 2D component and my obstacles will still work?

 

Rigid bodys are use to provide physics properties to your game objects. Colliders are used to detect collision areas and can be used with or without RB. When you remove a rigid body but keep the collider, the object becomes static, meaning that it can collide with other objects but it won't be affected by physics.

 

hmm..I need the RB so I can have the object move. I'm using the flappy bird game as my basis for study btw.



as seen in the image, I am trying to just make the green area of the building have the collision as I want the obstacles be the windows generated at random locations of the building(still working on the randomized location). So when the position of the green part changes, the collision are changes as well