force push example

week2/exercise2_jumpcontrol.md

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+The template for the character controller in Godot is very basic.
+
+```
+extends CharacterBody2D
+
+
+const SPEED = 300.0
+const JUMP_VELOCITY = -300.0
+
+# Get the gravity from the project settings to be synced with RigidBody nodes.
+var gravity = ProjectSettings.get_setting("physics/2d/default_gravity")
+
+
+func _physics_process(delta):
+	# Add the gravity.
+	if not is_on_floor():
+		velocity.y += gravity * delta
+
+	# Handle jump.
+	if Input.is_action_just_pressed("ui_accept") and is_on_floor():
+		velocity.y = JUMP_VELOCITY
+
+	# Get the input direction and handle the movement/deceleration.
+	# As good practice, you should replace UI actions with custom gameplay actions.
+	var direction = Input.get_axis("ui_left", "ui_right")
+	if direction:
+		velocity.x = direction * SPEED
+	else:
+		velocity.x = move_toward(velocity.x, 0, SPEED)
+
+	move_and_slide()
+```
+
+The basic template uses two helper functions `is_on_floor` and `move_and_slide` along with the `velocity` variable to achieve jumping, falling, and movement.
+
+Let us use some of our newfound knowledge of physics to improve our player character!
+
+### Exported Variables
+
+Exported variables allow us to make changes to them in the Godot editor. This is nice for play testing as it gives us a visual way to tweak our code. Let's take the imortant variables and export them.
+
+```
+@export var SPEED = 10400
+@export var JUMP_VELOCITY = -300
+```
+### Collisions with RigidBodies
+
+Each time a PlayerCharacter body moves via `move_and_slide` any colliders it made contact with are stored in an array that can be retrieved via the `get_slide_collision` method.
+
+We can use that to apply an impulse to any RigidBody the player collided with.
+
+```
+	# This represents the player's inertia
+	# after calling move_and_slide()
+	for i in get_slide_collision_count():
+		var c = get_slide_collision(i)
+		if c.get_collider() is RigidBody2D:
+			c.get_collider().apply_central_impulse(-c.get_normal() * PUSH_FORCE)
+```
+## Creating a Melee Force Push Attack
+
+We can use our new knowledge of impulses to do some pretty cool attacks agains RigidBodies!
+
+To pull off the attack we need to know:
+
+* Is there a target in range?
+* What direction is the player facing?
+* Is there a target in front of them in range?
+* Are they attacking?
+* How much force should be applied?
+
+To tell if there is a target in range, we can use a handy feature called a Raycast.
+
+### Raycasts
+
+Raycasts can be used to detect collisions within a very narrow line. They are very helpful for detecting objects within a certain proximity.
+
+We will use them to detect if there are any items we can attack with a force-push within range of the player character.
+
+First we make a reference to our two raycasts:
+
+```
+@onready var rightRay = $RightRaycast
+@onready var leftRay = $LeftRaycast
+var pushRightEnabled = false
+var pushLeftEnabled = false
+
+#note no type assigned
+var pushTarget
+#can not force-push right if facing left
+var faceLeft = false
+```
+
+When we detect the action of a raycast we need to respond. First of all, we need to track which direction the player is facing, assuming that they can only force-push in the direction they are facing.
+
+```
+if direction:
+		velocity.x = direction * SPEED
+		faceLeft = true if direction<0 else false
+```
+
+```
+if rightRay.is_colliding():
+		var collider = rightRay.get_collider()
+		if collider is Node:
+			if collider.is_in_group("boxes"):
+				pushRightEnabled = true
+				pushTarget = collider
+	else:
+		pushRightEnabled = false
+```
+
+And we can do the same for the left ray:
+
+```
+if leftRay.is_colliding():
+		var collider = leftRay.get_collider()
+		if collider is Node:
+			if collider.is_in_group("boxes"):
+				pushLeftEnabled = true
+				pushTarget = collider
+	else:
+		pushLeftEnabled = false
+```
+
+Now we just have to detect if the player is holding the force push button.
+
+```
+if Input.is_action_just_pressed("push") && pushRightEnabled && faceLeft == false:
+		label.text="shove"
+		pushTarget.apply_central_impulse(Vector2(1,0) * PUSH_FORCE * 20)
+		pushRightEnabled = false
+		
+	if Input.is_action_just_pressed("push") && pushLeftEnabled :
+		label.text="shove"
+		pushTarget.apply_central_impulse(Vector2(-1,0) * PUSH_FORCE * 20)
+		pushLeftEnabled = false
+```