pymunk_demo_platformer_10.py Full Listing#
pymunk_demo_platformer_10.py#
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Example of Pymunk Physics Engine Platformer
"""
import math
from typing import Optional
import arcade
SCREEN_TITLE = "PyMunk Platformer"
# How big are our image tiles?
SPRITE_IMAGE_SIZE = 128
# Scale sprites up or down
SPRITE_SCALING_PLAYER = 0.5
SPRITE_SCALING_TILES = 0.5
# Scaled sprite size for tiles
SPRITE_SIZE = int(SPRITE_IMAGE_SIZE * SPRITE_SCALING_PLAYER)
# Size of grid to show on screen, in number of tiles
SCREEN_GRID_WIDTH = 25
SCREEN_GRID_HEIGHT = 15
# Size of screen to show, in pixels
SCREEN_WIDTH = SPRITE_SIZE * SCREEN_GRID_WIDTH
SCREEN_HEIGHT = SPRITE_SIZE * SCREEN_GRID_HEIGHT
# --- Physics forces. Higher number, faster accelerating.
# Gravity
GRAVITY = 1500
# Damping - Amount of speed lost per second
DEFAULT_DAMPING = 1.0
PLAYER_DAMPING = 0.4
# Friction between objects
PLAYER_FRICTION = 1.0
WALL_FRICTION = 0.7
DYNAMIC_ITEM_FRICTION = 0.6
# Mass (defaults to 1)
PLAYER_MASS = 2.0
# Keep player from going too fast
PLAYER_MAX_HORIZONTAL_SPEED = 450
PLAYER_MAX_VERTICAL_SPEED = 1600
# Force applied while on the ground
PLAYER_MOVE_FORCE_ON_GROUND = 8000
# Force applied when moving left/right in the air
PLAYER_MOVE_FORCE_IN_AIR = 900
# Strength of a jump
PLAYER_JUMP_IMPULSE = 1800
# Close enough to not-moving to have the animation go to idle.
DEAD_ZONE = 0.1
# Constants used to track if the player is facing left or right
RIGHT_FACING = 0
LEFT_FACING = 1
# How many pixels to move before we change the texture in the walking animation
DISTANCE_TO_CHANGE_TEXTURE = 20
# How much force to put on the bullet
BULLET_MOVE_FORCE = 4500
# Mass of the bullet
BULLET_MASS = 0.1
# Make bullet less affected by gravity
BULLET_GRAVITY = 300
class PlayerSprite(arcade.Sprite):
""" Player Sprite """
def __init__(self):
""" Init """
# Let parent initialize
super().__init__()
# Set our scale
self.scale = SPRITE_SCALING_PLAYER
# Images from Kenney.nl's Character pack
# main_path = ":resources:images/animated_characters/female_adventurer/femaleAdventurer"
main_path = ":resources:images/animated_characters/female_person/femalePerson"
# main_path = ":resources:images/animated_characters/male_person/malePerson"
# main_path = ":resources:images/animated_characters/male_adventurer/maleAdventurer"
# main_path = ":resources:images/animated_characters/zombie/zombie"
# main_path = ":resources:images/animated_characters/robot/robot"
# Load textures for idle standing
self.idle_texture_pair = arcade.load_texture_pair(f"{main_path}_idle.png")
self.jump_texture_pair = arcade.load_texture_pair(f"{main_path}_jump.png")
self.fall_texture_pair = arcade.load_texture_pair(f"{main_path}_fall.png")
# Load textures for walking
self.walk_textures = []
for i in range(8):
texture = arcade.load_texture_pair(f"{main_path}_walk{i}.png")
self.walk_textures.append(texture)
# Set the initial texture
self.texture = self.idle_texture_pair[0]
# Hit box will be set based on the first image used.
self.hit_box = self.texture.hit_box_points
# Default to face-right
self.character_face_direction = RIGHT_FACING
# Index of our current texture
self.cur_texture = 0
# How far have we traveled horizontally since changing the texture
self.x_odometer = 0
def pymunk_moved(self, physics_engine, dx, dy, d_angle):
""" Handle being moved by the pymunk engine """
# Figure out if we need to face left or right
if dx < -DEAD_ZONE and self.character_face_direction == RIGHT_FACING:
self.character_face_direction = LEFT_FACING
elif dx > DEAD_ZONE and self.character_face_direction == LEFT_FACING:
self.character_face_direction = RIGHT_FACING
# Are we on the ground?
is_on_ground = physics_engine.is_on_ground(self)
# Add to the odometer how far we've moved
self.x_odometer += dx
# Jumping animation
if not is_on_ground:
if dy > DEAD_ZONE:
self.texture = self.jump_texture_pair[self.character_face_direction]
return
elif dy < -DEAD_ZONE:
self.texture = self.fall_texture_pair[self.character_face_direction]
return
# Idle animation
if abs(dx) <= DEAD_ZONE:
self.texture = self.idle_texture_pair[self.character_face_direction]
return
# Have we moved far enough to change the texture?
if abs(self.x_odometer) > DISTANCE_TO_CHANGE_TEXTURE:
# Reset the odometer
self.x_odometer = 0
# Advance the walking animation
self.cur_texture += 1
if self.cur_texture > 7:
self.cur_texture = 0
self.texture = self.walk_textures[self.cur_texture][self.character_face_direction]
class BulletSprite(arcade.SpriteSolidColor):
""" Bullet Sprite """
def pymunk_moved(self, physics_engine, dx, dy, d_angle):
""" Handle when the sprite is moved by the physics engine. """
# If the bullet falls below the screen, remove it
if self.center_y < -100:
self.remove_from_sprite_lists()
class GameWindow(arcade.Window):
""" Main Window """
def __init__(self, width, height, title):
""" Create the variables """
# Init the parent class
super().__init__(width, height, title)
# Player sprite
self.player_sprite: Optional[PlayerSprite] = None
# Sprite lists we need
self.player_list: Optional[arcade.SpriteList] = None
self.wall_list: Optional[arcade.SpriteList] = None
self.bullet_list: Optional[arcade.SpriteList] = None
self.item_list: Optional[arcade.SpriteList] = None
# Track the current state of what key is pressed
self.left_pressed: bool = False
self.right_pressed: bool = False
# Physics engine
self.physics_engine = Optional[arcade.PymunkPhysicsEngine]
# Set background color
arcade.set_background_color(arcade.color.AMAZON)
def setup(self):
""" Set up everything with the game """
# Create the sprite lists
self.player_list = arcade.SpriteList()
self.bullet_list = arcade.SpriteList()
# Map name
map_name = ":resources:/tiled_maps/pymunk_test_map.json"
# Load in TileMap
tile_map = arcade.load_tilemap(map_name, SPRITE_SCALING_TILES)
# Pull the sprite layers out of the tile map
self.wall_list = tile_map.sprite_lists["Platforms"]
self.item_list = tile_map.sprite_lists["Dynamic Items"]
# Create player sprite
self.player_sprite = PlayerSprite()
# Set player location
grid_x = 1
grid_y = 1
self.player_sprite.center_x = SPRITE_SIZE * grid_x + SPRITE_SIZE / 2
self.player_sprite.center_y = SPRITE_SIZE * grid_y + SPRITE_SIZE / 2
# Add to player sprite list
self.player_list.append(self.player_sprite)
# --- Pymunk Physics Engine Setup ---
# The default damping for every object controls the percent of velocity
# the object will keep each second. A value of 1.0 is no speed loss,
# 0.9 is 10% per second, 0.1 is 90% per second.
# For top-down games, this is basically the friction for moving objects.
# For platformers with gravity, this should probably be set to 1.0.
# Default value is 1.0 if not specified.
damping = DEFAULT_DAMPING
# Set the gravity. (0, 0) is good for outer space and top-down.
gravity = (0, -GRAVITY)
# Create the physics engine
self.physics_engine = arcade.PymunkPhysicsEngine(damping=damping,
gravity=gravity)
def wall_hit_handler(bullet_sprite, _wall_sprite, _arbiter, _space, _data):
""" Called for bullet/wall collision """
bullet_sprite.remove_from_sprite_lists()
self.physics_engine.add_collision_handler("bullet", "wall", post_handler=wall_hit_handler)
def item_hit_handler(bullet_sprite, item_sprite, _arbiter, _space, _data):
""" Called for bullet/wall collision """
bullet_sprite.remove_from_sprite_lists()
item_sprite.remove_from_sprite_lists()
self.physics_engine.add_collision_handler("bullet", "item", post_handler=item_hit_handler)
# Add the player.
# For the player, we set the damping to a lower value, which increases
# the damping rate. This prevents the character from traveling too far
# after the player lets off the movement keys.
# Setting the moment to PymunkPhysicsEngine.MOMENT_INF prevents it from
# rotating.
# Friction normally goes between 0 (no friction) and 1.0 (high friction)
# Friction is between two objects in contact. It is important to remember
# in top-down games that friction moving along the 'floor' is controlled
# by damping.
self.physics_engine.add_sprite(self.player_sprite,
friction=PLAYER_FRICTION,
mass=PLAYER_MASS,
moment=arcade.PymunkPhysicsEngine.MOMENT_INF,
collision_type="player",
max_horizontal_velocity=PLAYER_MAX_HORIZONTAL_SPEED,
max_vertical_velocity=PLAYER_MAX_VERTICAL_SPEED)
# Create the walls.
# By setting the body type to PymunkPhysicsEngine.STATIC the walls can't
# move.
# Movable objects that respond to forces are PymunkPhysicsEngine.DYNAMIC
# PymunkPhysicsEngine.KINEMATIC objects will move, but are assumed to be
# repositioned by code and don't respond to physics forces.
# Dynamic is default.
self.physics_engine.add_sprite_list(self.wall_list,
friction=WALL_FRICTION,
collision_type="wall",
body_type=arcade.PymunkPhysicsEngine.STATIC)
# Create the items
self.physics_engine.add_sprite_list(self.item_list,
friction=DYNAMIC_ITEM_FRICTION,
collision_type="item")
def on_key_press(self, key, modifiers):
"""Called whenever a key is pressed. """
if key == arcade.key.LEFT:
self.left_pressed = True
elif key == arcade.key.RIGHT:
self.right_pressed = True
elif key == arcade.key.UP:
# find out if player is standing on ground
if self.physics_engine.is_on_ground(self.player_sprite):
# She is! Go ahead and jump
impulse = (0, PLAYER_JUMP_IMPULSE)
self.physics_engine.apply_impulse(self.player_sprite, impulse)
def on_key_release(self, key, modifiers):
"""Called when the user releases a key. """
if key == arcade.key.LEFT:
self.left_pressed = False
elif key == arcade.key.RIGHT:
self.right_pressed = False
def on_mouse_press(self, x, y, button, modifiers):
""" Called whenever the mouse button is clicked. """
bullet = BulletSprite(20, 5, arcade.color.DARK_YELLOW)
self.bullet_list.append(bullet)
# Position the bullet at the player's current location
start_x = self.player_sprite.center_x
start_y = self.player_sprite.center_y
bullet.position = self.player_sprite.position
# Get from the mouse the destination location for the bullet
# IMPORTANT! If you have a scrolling screen, you will also need
# to add in self.view_bottom and self.view_left.
dest_x = x
dest_y = y
# Do math to calculate how to get the bullet to the destination.
# Calculation the angle in radians between the start points
# and end points. This is the angle the bullet will travel.
x_diff = dest_x - start_x
y_diff = dest_y - start_y
angle = math.atan2(y_diff, x_diff)
# What is the 1/2 size of this sprite, so we can figure out how far
# away to spawn the bullet
size = max(self.player_sprite.width, self.player_sprite.height) / 2
# Use angle to to spawn bullet away from player in proper direction
bullet.center_x += size * math.cos(angle)
bullet.center_y += size * math.sin(angle)
# Set angle of bullet
bullet.angle = math.degrees(angle)
# Gravity to use for the bullet
# If we don't use custom gravity, bullet drops too fast, or we have
# to make it go too fast.
# Force is in relation to bullet's angle.
bullet_gravity = (0, -BULLET_GRAVITY)
# Add the sprite. This needs to be done AFTER setting the fields above.
self.physics_engine.add_sprite(bullet,
mass=BULLET_MASS,
damping=1.0,
friction=0.6,
collision_type="bullet",
gravity=bullet_gravity,
elasticity=0.9)
# Add force to bullet
force = (BULLET_MOVE_FORCE, 0)
self.physics_engine.apply_force(bullet, force)
def on_update(self, delta_time):
""" Movement and game logic """
is_on_ground = self.physics_engine.is_on_ground(self.player_sprite)
# Update player forces based on keys pressed
if self.left_pressed and not self.right_pressed:
# Create a force to the left. Apply it.
if is_on_ground:
force = (-PLAYER_MOVE_FORCE_ON_GROUND, 0)
else:
force = (-PLAYER_MOVE_FORCE_IN_AIR, 0)
self.physics_engine.apply_force(self.player_sprite, force)
# Set friction to zero for the player while moving
self.physics_engine.set_friction(self.player_sprite, 0)
elif self.right_pressed and not self.left_pressed:
# Create a force to the right. Apply it.
if is_on_ground:
force = (PLAYER_MOVE_FORCE_ON_GROUND, 0)
else:
force = (PLAYER_MOVE_FORCE_IN_AIR, 0)
self.physics_engine.apply_force(self.player_sprite, force)
# Set friction to zero for the player while moving
self.physics_engine.set_friction(self.player_sprite, 0)
else:
# Player's feet are not moving. Therefore up the friction so we stop.
self.physics_engine.set_friction(self.player_sprite, 1.0)
# Move items in the physics engine
self.physics_engine.step()
def on_draw(self):
""" Draw everything """
self.clear()
self.wall_list.draw()
self.bullet_list.draw()
self.item_list.draw()
self.player_list.draw()
def main():
""" Main function """
window = GameWindow(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
window.setup()
arcade.run()
if __name__ == "__main__":
main()
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