Pymunk Demo - Top Down#
pymunk_demo_top_down.py#
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Example of Pymunk Physics Engine
Top-down
"""
import math
import random
import arcade
from typing import Optional
from arcade.pymunk_physics_engine import PymunkPhysicsEngine
SCREEN_TITLE = "PyMunk Top-Down"
SPRITE_SCALING_PLAYER = 0.5
MOVEMENT_SPEED = 5
SPRITE_IMAGE_SIZE = 128
SPRITE_SIZE = int(SPRITE_IMAGE_SIZE * SPRITE_SCALING_PLAYER)
SCREEN_WIDTH = SPRITE_SIZE * 15
SCREEN_HEIGHT = SPRITE_SIZE * 10
# Physics force used to move the player. Higher number, faster accelerating.
PLAYER_MOVE_FORCE = 4000
BULLET_MOVE_FORCE = 2500
class MyWindow(arcade.Window):
""" Main Window """
def __init__(self, width, height, title):
""" Init """
super().__init__(width, height, title)
arcade.set_background_color(arcade.color.AMAZON)
self.player_list = None
self.wall_list = None
self.bullet_list = None
self.rock_list = None
self.gem_list = None
self.player_sprite = None
self.physics_engine: Optional[PymunkPhysicsEngine] = None
# Track the current state of what key is pressed
self.left_pressed = False
self.right_pressed = False
self.up_pressed = False
self.down_pressed = False
def setup(self):
""" Set up everything """
# Create the sprite lists
self.player_list = arcade.SpriteList()
self.wall_list = arcade.SpriteList()
self.bullet_list = arcade.SpriteList()
self.rock_list = arcade.SpriteList()
self.gem_list = arcade.SpriteList()
# Set up the player
self.player_sprite = arcade.Sprite(":resources:images/animated_characters/female_person/"
"femalePerson_idle.png",
SPRITE_SCALING_PLAYER)
self.player_sprite.center_x = 250
self.player_sprite.center_y = 250
self.player_list.append(self.player_sprite)
# Set up the walls
for x in range(0, SCREEN_WIDTH + 1, SPRITE_SIZE):
wall = arcade.Sprite(":resources:images/tiles/grassCenter.png",
SPRITE_SCALING_PLAYER)
wall.center_x = x
wall.center_y = 0
self.wall_list.append(wall)
wall = arcade.Sprite(":resources:images/tiles/grassCenter.png",
SPRITE_SCALING_PLAYER)
wall.center_x = x
wall.center_y = SCREEN_HEIGHT
self.wall_list.append(wall)
# Set up the walls
for y in range(SPRITE_SIZE, SCREEN_HEIGHT, SPRITE_SIZE):
wall = arcade.Sprite(":resources:images/tiles/grassCenter.png",
SPRITE_SCALING_PLAYER)
wall.center_x = 0
wall.center_y = y
self.wall_list.append(wall)
wall = arcade.Sprite(":resources:images/tiles/grassCenter.png",
SPRITE_SCALING_PLAYER)
wall.center_x = SCREEN_WIDTH
wall.center_y = y
self.wall_list.append(wall)
# Add some movable rocks
for x in range(SPRITE_SIZE * 2, SPRITE_SIZE * 13, SPRITE_SIZE):
rock = random.randrange(4) + 1
item = arcade.Sprite(f":resources:images/space_shooter/meteorGrey_big{rock}.png",
SPRITE_SCALING_PLAYER)
item.center_x = x
item.center_y = 400
self.rock_list.append(item)
# Add some movable coins
for x in range(SPRITE_SIZE * 2, SPRITE_SIZE * 13, SPRITE_SIZE):
items = [":resources:images/items/gemBlue.png",
":resources:images/items/gemRed.png",
":resources:images/items/coinGold.png",
":resources:images/items/keyBlue.png"]
item_name = random.choice(items)
item = arcade.Sprite(item_name,
SPRITE_SCALING_PLAYER)
item.center_x = x
item.center_y = 300
self.gem_list.append(item)
# --- 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 = 0.7
# Set the gravity. (0, 0) is good for outer space and top-down.
gravity = (0, 0)
# Create the physics engine
self.physics_engine = PymunkPhysicsEngine(damping=damping,
gravity=gravity)
def rock_hit_handler(sprite_a, sprite_b, arbiter, space, data):
""" Called for bullet/rock collision """
bullet_shape = arbiter.shapes[0]
bullet_sprite = self.physics_engine.get_sprite_for_shape(bullet_shape)
bullet_sprite.remove_from_sprite_lists()
print("Rock")
def wall_hit_handler(sprite_a, sprite_b, arbiter, space, data):
""" Called for bullet/rock collision """
bullet_shape = arbiter.shapes[0]
bullet_sprite = self.physics_engine.get_sprite_for_shape(bullet_shape)
bullet_sprite.remove_from_sprite_lists()
print("Wall")
self.physics_engine.add_collision_handler("bullet", "rock", post_handler=rock_hit_handler)
self.physics_engine.add_collision_handler("bullet", "wall", post_handler=wall_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=0.6,
moment_of_inertia=PymunkPhysicsEngine.MOMENT_INF,
damping=0.01,
collision_type="player",
max_velocity=400)
# 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=0.6,
collision_type="wall",
body_type=PymunkPhysicsEngine.STATIC)
# Create some boxes to push around.
# Mass controls, well, the mass of an object. Defaults to 1.
self.physics_engine.add_sprite_list(self.rock_list,
mass=2,
friction=0.8,
damping=0.1,
collision_type="rock")
# Create some boxes to push around.
# Mass controls, well, the mass of an object. Defaults to 1.
self.physics_engine.add_sprite_list(self.gem_list,
mass=0.5,
friction=0.8,
damping=0.4,
collision_type="rock")
def on_mouse_press(self, x, y, button, modifiers):
""" Called whenever the mouse button is clicked. """
bullet = arcade.SpriteSolidColor(5, 5, arcade.color.RED)
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)
force = [math.cos(angle), math.sin(angle)]
size = max(self.player_sprite.width, self.player_sprite.height) / 2
bullet.center_x += size * force[0]
bullet.center_y += size * force[1]
self.physics_engine.add_sprite(bullet,
mass=0.1,
damping=1.0,
friction=0.6,
collision_type="bullet",
elasticity=0.9)
# Taking into account the angle, calculate our force.
force[0] *= BULLET_MOVE_FORCE
force[1] *= BULLET_MOVE_FORCE
self.physics_engine.apply_force(bullet, force)
def on_key_press(self, key, modifiers):
"""Called whenever a key is pressed. """
if key == arcade.key.UP:
self.up_pressed = True
elif key == arcade.key.DOWN:
self.down_pressed = True
elif key == arcade.key.LEFT:
self.left_pressed = True
elif key == arcade.key.RIGHT:
self.right_pressed = True
elif key == arcade.key.SPACE:
bullet = arcade.SpriteSolidColor(9, 9, arcade.color.RED)
bullet.position = self.player_sprite.position
bullet.center_x += 30
self.bullet_list.append(bullet)
self.physics_engine.add_sprite(bullet,
mass=0.2,
damping=1.0,
friction=0.6,
collision_type="bullet")
force = (3000, 0)
self.physics_engine.apply_force(bullet, force)
def on_key_release(self, key, modifiers):
"""Called when the user releases a key. """
if key == arcade.key.UP:
self.up_pressed = False
elif key == arcade.key.DOWN:
self.down_pressed = False
elif key == arcade.key.LEFT:
self.left_pressed = False
elif key == arcade.key.RIGHT:
self.right_pressed = False
def on_update(self, delta_time):
""" Movement and game logic """
# Calculate speed based on the keys pressed
self.player_sprite.change_x = 0
self.player_sprite.change_y = 0
if self.up_pressed and not self.down_pressed:
force = (0, PLAYER_MOVE_FORCE)
self.physics_engine.apply_force(self.player_sprite, force)
elif self.down_pressed and not self.up_pressed:
force = (0, -PLAYER_MOVE_FORCE)
self.physics_engine.apply_force(self.player_sprite, force)
if self.left_pressed and not self.right_pressed:
self.player_sprite.change_x = -MOVEMENT_SPEED
force = (-PLAYER_MOVE_FORCE, 0)
self.physics_engine.apply_force(self.player_sprite, force)
elif self.right_pressed and not self.left_pressed:
force = (PLAYER_MOVE_FORCE, 0)
self.physics_engine.apply_force(self.player_sprite, force)
# --- 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.rock_list.draw()
self.gem_list.draw()
self.player_list.draw()
def main():
""" Main function """
window = MyWindow(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
window.setup()
arcade.run()
if __name__ == "__main__":
main()
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