adding notes on body-body collision

ch01/lesson-12.org

@@ -3,7 +3,10 @@
 #+title: Lesson 12: Player-Enemy Collisions
 
 
-[[../../arpg/toc.org][< Back to Main TOC]]
+* Links
+- [[../../arpg/toc.org][< Back to Main TOC]]
+- [[https://youtu.be/WVQkOWY3zxQ?si=UILX6fBQ_Zw1cZoK][Player-enemy collision]]
+
 
 
 * Notes
@@ -16,14 +19,61 @@
 - select 'CapsuleShape2D' from dropdown
 
 *** modify shape
-- Go to Inspector->CollisionShape2D->Node2D
-- Open 'Transform'
+- Inspector->CollisionShape2D->Node2D->Transform
 - Go to Rotation and set to 90 degrees
 - Modify shape via handles to adjust it over sprite
 
-*** z-index
-- set :w
+*** set the z-index
+- in CollisionShape2D to 0
+- in sprite root node to 1
 
+*** make sure collision shape fits all the animation frames
+- go to the AnimateSprit2D node
+- Inspector->AnimatedSprite2D->Animation->Frame
+- scroll through the frames to see if they fit the collision shape properly
+
+** modify the player script to handle the collision
+
+*** default collision code
+- default collision handling occurs between two CharacterBody2D nodes
+- limits each others movements
+- occurs after the =move_and_slide= function is called
+
+#+begin_src godot
+# Using move_and_collide.
+var collision = move_and_collide(velocity * delta)
+if collision:
+    print("I collided with ", collision.get_collider().name)
+#+end_src
+
+*** handle collisions (scaffolding)
+- first get the number of collisions that occurred
+  - this is in =get_slide_collision_count()= function
+- loop through the number with an index
+  - in each loop get the /collision info object/ for that index with =get_slide_collisions()=
+    - =get_slide_collision= takes an index
+  - to get the /collider/ call =get_collider()= on the /collision info object/
+
+- the function scaffolding:
+#+begin_src godot
+# this is the basic function
+func handleCollision():
+    for i in get_slide_collision_count():
+        var collision = get_slide_collision(i)
+        var collider = collision.get_collider()
+        priint_debug(collider.name)
+#+end_src
+
+- place this function in =func _physics_process(delta)=
+  - put it after =move_and_slide= but before =updateAnimation=
+  - example:
+#+begin_src godot
+func _physics_process(delta):
+    handleInput()
+    move_and_slide()
+    handleCollision()
+    updateAnimation()
+#+end_src
 
 * Video Contents