pymunk_demo_platformer_09.py Full Listing#
pymunk_demo_platformer_09.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# Close enough to not-moving to have the animation go to idle.
59DEAD_ZONE = 0.1
60
61# Constants used to track if the player is facing left or right
62RIGHT_FACING = 0
63LEFT_FACING = 1
64
65# How many pixels to move before we change the texture in the walking animation
66DISTANCE_TO_CHANGE_TEXTURE = 20
67
68# How much force to put on the bullet
69BULLET_MOVE_FORCE = 4500
70
71# Mass of the bullet
72BULLET_MASS = 0.1
73
74# Make bullet less affected by gravity
75BULLET_GRAVITY = 300
76
77
78class PlayerSprite(arcade.Sprite):
79 """ Player Sprite """
80 def __init__(self):
81 """ Init """
82 # Let parent initialize
83 super().__init__()
84
85 # Set our scale
86 self.scale = SPRITE_SCALING_PLAYER
87
88 # Images from Kenney.nl's Character pack
89 # main_path = ":resources:images/animated_characters/female_adventurer/femaleAdventurer"
90 main_path = ":resources:images/animated_characters/female_person/femalePerson"
91 # main_path = ":resources:images/animated_characters/male_person/malePerson"
92 # main_path = ":resources:images/animated_characters/male_adventurer/maleAdventurer"
93 # main_path = ":resources:images/animated_characters/zombie/zombie"
94 # main_path = ":resources:images/animated_characters/robot/robot"
95
96 # Load textures for idle standing
97 self.idle_texture_pair = arcade.load_texture_pair(f"{main_path}_idle.png")
98 self.jump_texture_pair = arcade.load_texture_pair(f"{main_path}_jump.png")
99 self.fall_texture_pair = arcade.load_texture_pair(f"{main_path}_fall.png")
100
101 # Load textures for walking
102 self.walk_textures = []
103 for i in range(8):
104 texture = arcade.load_texture_pair(f"{main_path}_walk{i}.png")
105 self.walk_textures.append(texture)
106
107 # Set the initial texture
108 self.texture = self.idle_texture_pair[0]
109
110 # Default to face-right
111 self.character_face_direction = RIGHT_FACING
112
113 # Index of our current texture
114 self.cur_texture = 0
115
116 # How far have we traveled horizontally since changing the texture
117 self.x_odometer = 0
118
119 def pymunk_moved(self, physics_engine, dx, dy, d_angle):
120 """ Handle being moved by the pymunk engine """
121 # Figure out if we need to face left or right
122 if dx < -DEAD_ZONE and self.character_face_direction == RIGHT_FACING:
123 self.character_face_direction = LEFT_FACING
124 elif dx > DEAD_ZONE and self.character_face_direction == LEFT_FACING:
125 self.character_face_direction = RIGHT_FACING
126
127 # Are we on the ground?
128 is_on_ground = physics_engine.is_on_ground(self)
129
130 # Add to the odometer how far we've moved
131 self.x_odometer += dx
132
133 # Jumping animation
134 if not is_on_ground:
135 if dy > DEAD_ZONE:
136 self.texture = self.jump_texture_pair[self.character_face_direction]
137 return
138 elif dy < -DEAD_ZONE:
139 self.texture = self.fall_texture_pair[self.character_face_direction]
140 return
141
142 # Idle animation
143 if abs(dx) <= DEAD_ZONE:
144 self.texture = self.idle_texture_pair[self.character_face_direction]
145 return
146
147 # Have we moved far enough to change the texture?
148 if abs(self.x_odometer) > DISTANCE_TO_CHANGE_TEXTURE:
149
150 # Reset the odometer
151 self.x_odometer = 0
152
153 # Advance the walking animation
154 self.cur_texture += 1
155 if self.cur_texture > 7:
156 self.cur_texture = 0
157 self.texture = self.walk_textures[self.cur_texture][self.character_face_direction]
158
159
160class GameWindow(arcade.Window):
161 """ Main Window """
162
163 def __init__(self, width, height, title):
164 """ Create the variables """
165
166 # Init the parent class
167 super().__init__(width, height, title)
168
169 # Player sprite
170 self.player_sprite: Optional[PlayerSprite] = None
171
172 # Sprite lists we need
173 self.player_list: Optional[arcade.SpriteList] = None
174 self.wall_list: Optional[arcade.SpriteList] = None
175 self.bullet_list: Optional[arcade.SpriteList] = None
176 self.item_list: Optional[arcade.SpriteList] = None
177
178 # Track the current state of what key is pressed
179 self.left_pressed: bool = False
180 self.right_pressed: bool = False
181
182 # Physics engine
183 self.physics_engine = Optional[arcade.PymunkPhysicsEngine]
184
185 # Set background color
186 self.background_color = arcade.color.AMAZON
187
188 def setup(self):
189 """ Set up everything with the game """
190
191 # Create the sprite lists
192 self.player_list = arcade.SpriteList()
193 self.bullet_list = arcade.SpriteList()
194
195 # Map name
196 map_name = ":resources:/tiled_maps/pymunk_test_map.json"
197
198 # Load in TileMap
199 tile_map = arcade.load_tilemap(map_name, SPRITE_SCALING_TILES)
200
201 # Pull the sprite layers out of the tile map
202 self.wall_list = tile_map.sprite_lists["Platforms"]
203 self.item_list = tile_map.sprite_lists["Dynamic Items"]
204
205 # Create player sprite
206 self.player_sprite = PlayerSprite()
207
208 # Set player location
209 grid_x = 1
210 grid_y = 1
211 self.player_sprite.center_x = SPRITE_SIZE * grid_x + SPRITE_SIZE / 2
212 self.player_sprite.center_y = SPRITE_SIZE * grid_y + SPRITE_SIZE / 2
213 # Add to player sprite list
214 self.player_list.append(self.player_sprite)
215
216 # --- Pymunk Physics Engine Setup ---
217
218 # The default damping for every object controls the percent of velocity
219 # the object will keep each second. A value of 1.0 is no speed loss,
220 # 0.9 is 10% per second, 0.1 is 90% per second.
221 # For top-down games, this is basically the friction for moving objects.
222 # For platformers with gravity, this should probably be set to 1.0.
223 # Default value is 1.0 if not specified.
224 damping = DEFAULT_DAMPING
225
226 # Set the gravity. (0, 0) is good for outer space and top-down.
227 gravity = (0, -GRAVITY)
228
229 # Create the physics engine
230 self.physics_engine = arcade.PymunkPhysicsEngine(damping=damping,
231 gravity=gravity)
232
233 # Add the player.
234 # For the player, we set the damping to a lower value, which increases
235 # the damping rate. This prevents the character from traveling too far
236 # after the player lets off the movement keys.
237 # Setting the moment of inertia to PymunkPhysicsEngine.MOMENT_INF prevents it from
238 # rotating.
239 # Friction normally goes between 0 (no friction) and 1.0 (high friction)
240 # Friction is between two objects in contact. It is important to remember
241 # in top-down games that friction moving along the 'floor' is controlled
242 # by damping.
243 self.physics_engine.add_sprite(self.player_sprite,
244 friction=PLAYER_FRICTION,
245 mass=PLAYER_MASS,
246 moment_of_inertia=arcade.PymunkPhysicsEngine.MOMENT_INF,
247 collision_type="player",
248 max_horizontal_velocity=PLAYER_MAX_HORIZONTAL_SPEED,
249 max_vertical_velocity=PLAYER_MAX_VERTICAL_SPEED)
250
251 # Create the walls.
252 # By setting the body type to PymunkPhysicsEngine.STATIC the walls can't
253 # move.
254 # Movable objects that respond to forces are PymunkPhysicsEngine.DYNAMIC
255 # PymunkPhysicsEngine.KINEMATIC objects will move, but are assumed to be
256 # repositioned by code and don't respond to physics forces.
257 # Dynamic is default.
258 self.physics_engine.add_sprite_list(self.wall_list,
259 friction=WALL_FRICTION,
260 collision_type="wall",
261 body_type=arcade.PymunkPhysicsEngine.STATIC)
262
263 # Create the items
264 self.physics_engine.add_sprite_list(self.item_list,
265 friction=DYNAMIC_ITEM_FRICTION,
266 collision_type="item")
267
268 def on_key_press(self, key, modifiers):
269 """Called whenever a key is pressed. """
270
271 if key == arcade.key.LEFT:
272 self.left_pressed = True
273 elif key == arcade.key.RIGHT:
274 self.right_pressed = True
275 elif key == arcade.key.UP:
276 # find out if player is standing on ground
277 if self.physics_engine.is_on_ground(self.player_sprite):
278 # She is! Go ahead and jump
279 impulse = (0, PLAYER_JUMP_IMPULSE)
280 self.physics_engine.apply_impulse(self.player_sprite, impulse)
281
282 def on_key_release(self, key, modifiers):
283 """Called when the user releases a key. """
284
285 if key == arcade.key.LEFT:
286 self.left_pressed = False
287 elif key == arcade.key.RIGHT:
288 self.right_pressed = False
289
290 def on_mouse_press(self, x, y, button, modifiers):
291 """ Called whenever the mouse button is clicked. """
292
293 bullet = arcade.SpriteSolidColor(width=20, height=5, color=arcade.color.DARK_YELLOW)
294 self.bullet_list.append(bullet)
295
296 # Position the bullet at the player's current location
297 start_x = self.player_sprite.center_x
298 start_y = self.player_sprite.center_y
299 bullet.position = self.player_sprite.position
300
301 # Get from the mouse the destination location for the bullet
302 # IMPORTANT! If you have a scrolling screen, you will also need
303 # to add in self.view_bottom and self.view_left.
304 dest_x = x
305 dest_y = y
306
307 # Do math to calculate how to get the bullet to the destination.
308 # Calculation the angle in radians between the start points
309 # and end points. This is the angle the bullet will travel.
310 x_diff = dest_x - start_x
311 y_diff = dest_y - start_y
312 angle = math.atan2(y_diff, x_diff)
313
314 # What is the 1/2 size of this sprite, so we can figure out how far
315 # away to spawn the bullet
316 size = max(self.player_sprite.width, self.player_sprite.height) / 2
317
318 # Use angle to to spawn bullet away from player in proper direction
319 bullet.center_x += size * math.cos(angle)
320 bullet.center_y += size * math.sin(angle)
321
322 # Set angle of bullet
323 bullet.angle = math.degrees(angle)
324
325 # Gravity to use for the bullet
326 # If we don't use custom gravity, bullet drops too fast, or we have
327 # to make it go too fast.
328 # Force is in relation to bullet's angle.
329 bullet_gravity = (0, -BULLET_GRAVITY)
330
331 # Add the sprite. This needs to be done AFTER setting the fields above.
332 self.physics_engine.add_sprite(bullet,
333 mass=BULLET_MASS,
334 damping=1.0,
335 friction=0.6,
336 collision_type="bullet",
337 gravity=bullet_gravity,
338 elasticity=0.9)
339
340 # Add force to bullet
341 force = (BULLET_MOVE_FORCE, 0)
342 self.physics_engine.apply_force(bullet, force)
343
344 def on_update(self, delta_time):
345 """ Movement and game logic """
346
347 is_on_ground = self.physics_engine.is_on_ground(self.player_sprite)
348 # Update player forces based on keys pressed
349 if self.left_pressed and not self.right_pressed:
350 # Create a force to the left. Apply it.
351 if is_on_ground:
352 force = (-PLAYER_MOVE_FORCE_ON_GROUND, 0)
353 else:
354 force = (-PLAYER_MOVE_FORCE_IN_AIR, 0)
355 self.physics_engine.apply_force(self.player_sprite, force)
356 # Set friction to zero for the player while moving
357 self.physics_engine.set_friction(self.player_sprite, 0)
358 elif self.right_pressed and not self.left_pressed:
359 # Create a force to the right. Apply it.
360 if is_on_ground:
361 force = (PLAYER_MOVE_FORCE_ON_GROUND, 0)
362 else:
363 force = (PLAYER_MOVE_FORCE_IN_AIR, 0)
364 self.physics_engine.apply_force(self.player_sprite, force)
365 # Set friction to zero for the player while moving
366 self.physics_engine.set_friction(self.player_sprite, 0)
367 else:
368 # Player's feet are not moving. Therefore up the friction so we stop.
369 self.physics_engine.set_friction(self.player_sprite, 1.0)
370
371 # Move items in the physics engine
372 self.physics_engine.step()
373
374 def on_draw(self):
375 """ Draw everything """
376 self.clear()
377 self.wall_list.draw()
378 self.bullet_list.draw()
379 self.item_list.draw()
380 self.player_list.draw()
381
382def main():
383 """ Main function """
384 window = GameWindow(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
385 window.setup()
386 arcade.run()
387
388
389if __name__ == "__main__":
390 main()