pymunk_demo_platformer_07.py Full Listing#

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