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Billiard
This example shows how to implement a very simple Billiard game with Box2D
/home/runner/.local/lib/python3.10/site-packages/b2d/testbed/backend/matplotlib_gif_gui/matplotlib_gif_gui.py:52: UserWarning: You passed in an explicit save_count=240 which is being ignored in favor of frames=240.
self.ani = animation.FuncAnimation(
from b2d.testbed import TestbedBase
import random
import numpy
import b2d
import math
import random
class Billiard(TestbedBase):
name = "Billiard"
def __init__(self, settings=None):
super(Billiard, self).__init__(gravity=(0, 0), settings=settings)
dimensions = [30, 50]
self.dimensions = dimensions
# the outer box
box_shape = b2d.ChainShape()
box_shape.create_loop(
[
(0, 0),
(0, dimensions[1]),
(dimensions[0], dimensions[1]),
(dimensions[0], 0),
]
)
self.ball_radius = 1
box = self.world.create_static_body(
position=(0, 0), fixtures=b2d.fixture_def(shape=box_shape, friction=0)
)
self.place_balls()
self.place_pockets()
# mouse interaction
self._selected_ball = None
self._selected_ball_pos = None
self._last_pos = None
# balls to be destroyed in the next step
# since they are in the pocket
self._to_be_destroyed = []
def place_pockets(self):
pocket_radius = 1
self.pockets = []
def place_pocket(position):
pocket_shape = b2d.circle_shape(radius=pocket_radius / 3)
pocket = self.world.create_static_body(
position=position,
fixtures=b2d.fixture_def(shape=pocket_shape, is_sensor=True),
user_data=("pocket", None),
)
self.pockets.append(pocket)
d = pocket_radius / 2
place_pocket(position=(0 + d, 0 + d))
place_pocket(position=(self.dimensions[0] - d, 0 + d))
place_pocket(position=(0 + d, self.dimensions[1] / 2))
place_pocket(position=(self.dimensions[0] - d, self.dimensions[1] / 2))
place_pocket(position=(0 + d, self.dimensions[1] - d))
place_pocket(position=(self.dimensions[0] - d, self.dimensions[1] - d))
def place_balls(self):
self.balls = []
base_colors = [
(1, 1, 0),
(0, 0, 1),
(1, 0, 0),
(1, 0, 1),
(1, 0.6, 0),
(0, 1, 0),
(0.7, 0.4, 0.4),
]
colors = []
for color in base_colors:
# ``full`` ball
colors.append((color, color))
# ``half`` ball (half white)
colors.append((color, (1, 1, 1)))
random.shuffle(colors)
colors.insert(4, ((0, 0, 0), (0, 0, 0))) # black
n_y = 5
c_x = self.dimensions[0] / 2
diameter = (self.ball_radius * 2) * 1.01
bi = 0
for y in range(n_y):
py = y * diameter * 0.5 * math.sqrt(3)
n_x = y + 1
ox = diameter * (n_y - y) / 2
for x in range(y + 1):
position = (x * diameter + 10 + ox, py + 30)
self.create_billard_ball(position=position, color=colors[bi])
bi += 1
self.create_billard_ball(position=(c_x, 10), color=((1, 1, 1), (1, 1, 1)))
def create_billard_ball(self, position, color):
ball = self.world.create_dynamic_body(
position=position,
fixtures=b2d.fixture_def(
shape=b2d.circle_shape(radius=self.ball_radius),
density=1.0,
restitution=0.8,
),
linear_damping=0.4,
user_data=("ball", color),
fixed_rotation=True,
)
self.balls.append(ball)
def begin_contact(self, contact):
body_a = contact.body_a
body_b = contact.body_b
ud_a = body_a.user_data
ud_b = body_b.user_data
if ud_a is None or ud_b is None:
return
if ud_b[0] == "ball":
body_a, body_b = body_b, body_a
ud_a, ud_b = ud_b, ud_a
if ud_a[0] == "ball" and ud_b[0] == "pocket":
self._to_be_destroyed.append(body_a)
def pre_step(self, dt):
for b in self._to_be_destroyed:
self.balls.remove(b)
self.world.destroy_body(b)
self._to_be_destroyed = []
def ball_at_position(self, pos):
body = self.world.find_body(pos)
if body is not None:
user_data = body.user_data
if user_data is not None and user_data[0] == "ball":
return body
return None
def on_mouse_down(self, pos):
body = self.ball_at_position(pos)
if body is not None:
self._selected_ball = body
self._selected_ball_pos = pos
return True
return False
def on_mouse_move(self, pos):
if self._selected_ball is not None:
self._last_pos = pos
return False
def on_mouse_up(self, pos):
if self._selected_ball is not None:
self._last_pos = pos
# if the mouse is in the starting ball itself we do nothing
if self.ball_at_position(pos) != self._selected_ball:
delta = b2d.vec2(self._selected_ball_pos) - b2d.vec2(self._last_pos)
delta *= 100.0
self._selected_ball.apply_linear_impulse(
delta, self._selected_ball_pos, True
)
self._selected_ball = None
self._selected_ball_pos = None
self._last_pos = None
return False
def post_debug_draw(self):
for pocket in self.pockets:
self.debug_draw.draw_solid_circle(
pocket.position, self.ball_radius, (1, 0), (1, 1, 1)
)
for ball in self.balls:
_, (color0, color1) = ball.user_data
self.debug_draw.draw_solid_circle(
ball.position, self.ball_radius, (1, 0), color0
)
self.debug_draw.draw_solid_circle(
ball.position, self.ball_radius / 2, (1, 0), color1
)
self.debug_draw.draw_circle(
ball.position, self.ball_radius, (1, 1, 1), line_width=0.1
)
if self._selected_ball is not None:
# draw circle around selected ball
self.debug_draw.draw_circle(
self._selected_ball.position,
self.ball_radius * 2,
(1, 1, 1),
line_width=0.2,
)
# mark position on selected ball with red dot
self.debug_draw.draw_solid_circle(
self._selected_ball_pos, self.ball_radius * 0.2, (1, 0), (1, 0, 0)
)
# draw the line between marked pos on ball and last pos
if self._last_pos is not None:
self.debug_draw.draw_segment(
self._selected_ball_pos, self._last_pos, (1, 1, 1), line_width=0.2
)
if __name__ == "__main__":
ani = b2d.testbed.run(Billiard)
ani
Total running time of the script: ( 0 minutes 37.818 seconds)