The previous example great for top-down, but what if it is a side view with jumping like our platformer? We need to add gravity. First, let's define a constant to represent the acceleration for gravity, and one for a jump speed.
../../../arcade/examples/platform_tutorial/05_add_gravity.py
At the end of the setup method, change the physics engine to PhysicsEnginePlatformer and include gravity as a parameter.
../../../arcade/examples/platform_tutorial/05_add_gravity.py
We are sending our SpriteList for the things the player should collide with to the walls parameter of the the physics engine. As we'll see in later chapters, the platformer physics engine has a platforms and walls parameter. The difference between these is very important. Static non-moving spritelists should always be sent to the walls parameter, and moving sprites should be sent to the platforms parameter. Ensuring you do this will have extreme benefits to performance.
Adding static sprites via the platforms parameter is roughly an O(n) operation, meaning performance will linearly get worse as you add more sprites. If you add your static sprites via the walls parameter, then it is nearly O(1) and there is essentially no difference between for example 100 and 50,000 non-moving sprites.
We also see here some new syntax relating to our Scene object. You can access the scene like you would a Python dictionary in order to get your SpriteLists from it. There are multiple ways to access the SpriteLists within a Scene but this is the easiest and most straight forward. You could alternatively use scene.get_sprite_list("My Layer").
Then, modify the key down and key up event handlers. We'll remove the up/down statements we had before, and make 'UP' jump when pressed.
../../../arcade/examples/platform_tutorial/05_add_gravity.py
Note
You can change how the user jumps by changing the gravity and jump constants. Lower values for both will make for a more "floaty" character. Higher values make for a faster-paced game.
../../../arcade/examples/platform_tutorial/05_add_gravity.py