Make a character pushing blocks with KinematicBody2D

fuego

Greetings community, I am beginning to learn this engine by creating a simple 2D platformer with Tilemaps. I followed the Kinematic Character 2D tutorial (http://docs.godotengine.org/en/latest/tutorials/2d/kinematic_character_2d.html) to implement basic Tilemap collision and character movement, but now I am facing the need to implement the character's action to push a block. The character simply needs to push and slide a square block over the floor. My initial idea was to to create a Block scene using a KinematicBody2D and apply a script which replicates gravity logic and tries to detect collisions with the character. Then set the character's velocity.x on it. But once the block hits the floor, I found out it becomes like "static" and it doesn't detect any collision with the character. Then I tried to move the collision detection logic to the character script, but once it collides with the block and sets velocity.x, the block keeps sliding over and over and I can't find a way to know when to stop it. Someone could help me solving this problem, preferably not using physics based objects? Thanks in advance.

fuego

I resolved by placing 2 RayCast2D nodes on the block scene, one for left direction and another for right. Raycasts start from the block center and are long half the block width, plus 2-3 margin pixels as depicted in the figure below: <img src="http://i64.tinypic.com/j0bacm.png" alt="" title="Image: http://i64.tinypic.com/j0bacm.png"> Now, via GDScript I can detect the character colliding with both raycasts and I can set the correct velocity to the block. You have to tweak a little bit the logic, but I think this is the correct way to solve this problem.

zadig

If I'm not mistaken, placing the raycasts origin in the center of the character (assuming that the character holds a collision shape) will make 'em report collisions all the time. If that's the case you may need to set the origin of the raycasts outside the collisionshape.

fuego

Hi Zadig, thanks for the suggestion :) I added collision exceptions to the raycasts to solve this problem, but I just modified my scene and put the raycasts outside the CollisionPolygon to make it cleaner. By the way, raycasts are not placed in the character scene, but on the block scene instead, with the purpose to not clutter the character script with the management of other objects which it can interact. Maybe would this result in performance issues, handling many _fixed_process() functions?