pymunk_demo_platformer_07.py Full Listing#

pymunk_demo_platformer_07.py#
  1"""
  2Example of Pymunk Physics Engine Platformer
  3"""
  4import math
  5from typing import Optional
  6import arcade
  7
  8SCREEN_TITLE = "PyMunk Platformer"
  9
 10# How big are our image tiles?
 11SPRITE_IMAGE_SIZE = 128
 12
 13# Scale sprites up or down
 14SPRITE_SCALING_PLAYER = 0.5
 15SPRITE_SCALING_TILES = 0.5
 16
 17# Scaled sprite size for tiles
 18SPRITE_SIZE = int(SPRITE_IMAGE_SIZE * SPRITE_SCALING_PLAYER)
 19
 20# Size of grid to show on screen, in number of tiles
 21SCREEN_GRID_WIDTH = 25
 22SCREEN_GRID_HEIGHT = 15
 23
 24# Size of screen to show, in pixels
 25SCREEN_WIDTH = SPRITE_SIZE * SCREEN_GRID_WIDTH
 26SCREEN_HEIGHT = SPRITE_SIZE * SCREEN_GRID_HEIGHT
 27
 28# --- Physics forces. Higher number, faster accelerating.
 29
 30# Gravity
 31GRAVITY = 1500
 32
 33# Damping - Amount of speed lost per second
 34DEFAULT_DAMPING = 1.0
 35PLAYER_DAMPING = 0.4
 36
 37# Friction between objects
 38PLAYER_FRICTION = 1.0
 39WALL_FRICTION = 0.7
 40DYNAMIC_ITEM_FRICTION = 0.6
 41
 42# Mass (defaults to 1)
 43PLAYER_MASS = 2.0
 44
 45# Keep player from going too fast
 46PLAYER_MAX_HORIZONTAL_SPEED = 450
 47PLAYER_MAX_VERTICAL_SPEED = 1600
 48
 49# Force applied while on the ground
 50PLAYER_MOVE_FORCE_ON_GROUND = 8000
 51
 52# Force applied when moving left/right in the air
 53PLAYER_MOVE_FORCE_IN_AIR = 900
 54
 55# Strength of a jump
 56PLAYER_JUMP_IMPULSE = 1800
 57
 58
 59class GameWindow(arcade.Window):
 60    """ Main Window """
 61
 62    def __init__(self, width, height, title):
 63        """ Create the variables """
 64
 65        # Init the parent class
 66        super().__init__(width, height, title)
 67
 68        # Player sprite
 69        self.player_sprite: Optional[arcade.Sprite] = None
 70
 71        # Sprite lists we need
 72        self.player_list: Optional[arcade.SpriteList] = None
 73        self.wall_list: Optional[arcade.SpriteList] = None
 74        self.bullet_list: Optional[arcade.SpriteList] = None
 75        self.item_list: Optional[arcade.SpriteList] = None
 76
 77        # Track the current state of what key is pressed
 78        self.left_pressed: bool = False
 79        self.right_pressed: bool = False
 80
 81        # Physics engine
 82        self.physics_engine = Optional[arcade.PymunkPhysicsEngine]
 83
 84        # Set background color
 85        arcade.set_background_color(arcade.color.AMAZON)
 86
 87    def setup(self):
 88        """ Set up everything with the game """
 89
 90        # Create the sprite lists
 91        self.player_list = arcade.SpriteList()
 92        self.bullet_list = arcade.SpriteList()
 93
 94        # Map name
 95        map_name = ":resources:/tiled_maps/pymunk_test_map.json"
 96
 97        # Load in TileMap
 98        tile_map = arcade.load_tilemap(map_name, SPRITE_SCALING_TILES)
 99
100        # Pull the sprite layers out of the tile map
101        self.wall_list = tile_map.sprite_lists["Platforms"]
102        self.item_list = tile_map.sprite_lists["Dynamic Items"]
103
104        # Create player sprite
105        self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/femalePerson_idle.png",
106                                           SPRITE_SCALING_PLAYER)
107        # Set player location
108        grid_x = 1
109        grid_y = 1
110        self.player_sprite.center_x = SPRITE_SIZE * grid_x + SPRITE_SIZE / 2
111        self.player_sprite.center_y = SPRITE_SIZE * grid_y + SPRITE_SIZE / 2
112        # Add to player sprite list
113        self.player_list.append(self.player_sprite)
114
115        # --- Pymunk Physics Engine Setup ---
116
117        # The default damping for every object controls the percent of velocity
118        # the object will keep each second. A value of 1.0 is no speed loss,
119        # 0.9 is 10% per second, 0.1 is 90% per second.
120        # For top-down games, this is basically the friction for moving objects.
121        # For platformers with gravity, this should probably be set to 1.0.
122        # Default value is 1.0 if not specified.
123        damping = DEFAULT_DAMPING
124
125        # Set the gravity. (0, 0) is good for outer space and top-down.
126        gravity = (0, -GRAVITY)
127
128        # Create the physics engine
129        self.physics_engine = arcade.PymunkPhysicsEngine(damping=damping,
130                                                         gravity=gravity)
131
132        # Add the player.
133        # For the player, we set the damping to a lower value, which increases
134        # the damping rate. This prevents the character from traveling too far
135        # after the player lets off the movement keys.
136        # Setting the moment to PymunkPhysicsEngine.MOMENT_INF prevents it from
137        # rotating.
138        # Friction normally goes between 0 (no friction) and 1.0 (high friction)
139        # Friction is between two objects in contact. It is important to remember
140        # in top-down games that friction moving along the 'floor' is controlled
141        # by damping.
142        self.physics_engine.add_sprite(self.player_sprite,
143                                       friction=PLAYER_FRICTION,
144                                       mass=PLAYER_MASS,
145                                       moment=arcade.PymunkPhysicsEngine.MOMENT_INF,
146                                       collision_type="player",
147                                       max_horizontal_velocity=PLAYER_MAX_HORIZONTAL_SPEED,
148                                       max_vertical_velocity=PLAYER_MAX_VERTICAL_SPEED)
149
150        # Create the walls.
151        # By setting the body type to PymunkPhysicsEngine.STATIC the walls can't
152        # move.
153        # Movable objects that respond to forces are PymunkPhysicsEngine.DYNAMIC
154        # PymunkPhysicsEngine.KINEMATIC objects will move, but are assumed to be
155        # repositioned by code and don't respond to physics forces.
156        # Dynamic is default.
157        self.physics_engine.add_sprite_list(self.wall_list,
158                                            friction=WALL_FRICTION,
159                                            collision_type="wall",
160                                            body_type=arcade.PymunkPhysicsEngine.STATIC)
161
162        # Create the items
163        self.physics_engine.add_sprite_list(self.item_list,
164                                            friction=DYNAMIC_ITEM_FRICTION,
165                                            collision_type="item")
166
167    def on_key_press(self, key, modifiers):
168        """Called whenever a key is pressed. """
169
170        if key == arcade.key.LEFT:
171            self.left_pressed = True
172        elif key == arcade.key.RIGHT:
173            self.right_pressed = True
174        elif key == arcade.key.UP:
175            # find out if player is standing on ground
176            if self.physics_engine.is_on_ground(self.player_sprite):
177                # She is! Go ahead and jump
178                impulse = (0, PLAYER_JUMP_IMPULSE)
179                self.physics_engine.apply_impulse(self.player_sprite, impulse)
180
181    def on_key_release(self, key, modifiers):
182        """Called when the user releases a key. """
183
184        if key == arcade.key.LEFT:
185            self.left_pressed = False
186        elif key == arcade.key.RIGHT:
187            self.right_pressed = False
188
189    def on_update(self, delta_time):
190        """ Movement and game logic """
191
192        is_on_ground = self.physics_engine.is_on_ground(self.player_sprite)
193        # Update player forces based on keys pressed
194        if self.left_pressed and not self.right_pressed:
195            # Create a force to the left. Apply it.
196            if is_on_ground:
197                force = (-PLAYER_MOVE_FORCE_ON_GROUND, 0)
198            else:
199                force = (-PLAYER_MOVE_FORCE_IN_AIR, 0)
200            self.physics_engine.apply_force(self.player_sprite, force)
201            # Set friction to zero for the player while moving
202            self.physics_engine.set_friction(self.player_sprite, 0)
203        elif self.right_pressed and not self.left_pressed:
204            # Create a force to the right. Apply it.
205            if is_on_ground:
206                force = (PLAYER_MOVE_FORCE_ON_GROUND, 0)
207            else:
208                force = (PLAYER_MOVE_FORCE_IN_AIR, 0)
209            self.physics_engine.apply_force(self.player_sprite, force)
210            # Set friction to zero for the player while moving
211            self.physics_engine.set_friction(self.player_sprite, 0)
212        else:
213            # Player's feet are not moving. Therefore up the friction so we stop.
214            self.physics_engine.set_friction(self.player_sprite, 1.0)
215
216        # Move items in the physics engine
217        self.physics_engine.step()
218
219    def on_draw(self):
220        """ Draw everything """
221        self.clear()
222        self.wall_list.draw()
223        self.bullet_list.draw()
224        self.item_list.draw()
225        self.player_list.draw()
226
227def main():
228    """ Main function """
229    window = GameWindow(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
230    window.setup()
231    arcade.run()
232
233
234if __name__ == "__main__":
235    main()