Note
Click here to download the full example code
Pong#
A Matplotlib based game of Pong illustrating one way to write interactive animations that are easily ported to multiple backends.
Note
This example exercises the interactive capabilities of Matplotlib, and this will not appear in the static documentation. Please run this code on your machine to see the interactivity.
You can copy and paste individual parts, or download the entire example using the link at the bottom of the page.
import time
import numpy as np
import matplotlib.pyplot as plt
from numpy.random import randn, randint
from matplotlib.font_manager import FontProperties
instructions = """
Player A: Player B:
'e' up 'i'
'd' down 'k'
press 't' -- close these instructions
(animation will be much faster)
press 'a' -- add a puck
press 'A' -- remove a puck
press '1' -- slow down all pucks
press '2' -- speed up all pucks
press '3' -- slow down distractors
press '4' -- speed up distractors
press ' ' -- reset the first puck
press 'n' -- toggle distractors on/off
press 'g' -- toggle the game on/off
"""
class Pad:
def __init__(self, disp, x, y, type='l'):
self.disp = disp
self.x = x
self.y = y
self.w = .3
self.score = 0
self.xoffset = 0.3
self.yoffset = 0.1
if type == 'r':
self.xoffset *= -1.0
if type == 'l' or type == 'r':
self.signx = -1.0
self.signy = 1.0
else:
self.signx = 1.0
self.signy = -1.0
def contains(self, loc):
return self.disp.get_bbox().contains(loc.x, loc.y)
class Puck:
def __init__(self, disp, pad, field):
self.vmax = .2
self.disp = disp
self.field = field
self._reset(pad)
def _reset(self, pad):
self.x = pad.x + pad.xoffset
if pad.y < 0:
self.y = pad.y + pad.yoffset
else:
self.y = pad.y - pad.yoffset
self.vx = pad.x - self.x
self.vy = pad.y + pad.w/2 - self.y
self._speedlimit()
self._slower()
self._slower()
def update(self, pads):
self.x += self.vx
self.y += self.vy
for pad in pads:
if pad.contains(self):
self.vx *= 1.2 * pad.signx
self.vy *= 1.2 * pad.signy
fudge = .001
# probably cleaner with something like...
if self.x < fudge:
pads[1].score += 1
self._reset(pads[0])
return True
if self.x > 7 - fudge:
pads[0].score += 1
self._reset(pads[1])
return True
if self.y < -1 + fudge or self.y > 1 - fudge:
self.vy *= -1.0
# add some randomness, just to make it interesting
self.vy -= (randn()/300.0 + 1/300.0) * np.sign(self.vy)
self._speedlimit()
return False
def _slower(self):
self.vx /= 5.0
self.vy /= 5.0
def _faster(self):
self.vx *= 5.0
self.vy *= 5.0
def _speedlimit(self):
if self.vx > self.vmax:
self.vx = self.vmax
if self.vx < -self.vmax:
self.vx = -self.vmax
if self.vy > self.vmax:
self.vy = self.vmax
if self.vy < -self.vmax:
self.vy = -self.vmax
class Game:
def __init__(self, ax):
# create the initial line
self.ax = ax
ax.xaxis.set_visible(False)
ax.set_xlim([0, 7])
ax.yaxis.set_visible(False)
ax.set_ylim([-1, 1])
pad_a_x = 0
pad_b_x = .50
pad_a_y = pad_b_y = .30
pad_b_x += 6.3
# pads
pA, = self.ax.barh(pad_a_y, .2,
height=.3, color='k', alpha=.5, edgecolor='b',
lw=2, label="Player B",
animated=True)
pB, = self.ax.barh(pad_b_y, .2,
height=.3, left=pad_b_x, color='k', alpha=.5,
edgecolor='r', lw=2, label="Player A",
animated=True)
# distractors
self.x = np.arange(0, 2.22*np.pi, 0.01)
self.line, = self.ax.plot(self.x, np.sin(self.x), "r",
animated=True, lw=4)
self.line2, = self.ax.plot(self.x, np.cos(self.x), "g",
animated=True, lw=4)
self.line3, = self.ax.plot(self.x, np.cos(self.x), "g",
animated=True, lw=4)
self.line4, = self.ax.plot(self.x, np.cos(self.x), "r",
animated=True, lw=4)
# center line
self.centerline, = self.ax.plot([3.5, 3.5], [1, -1], 'k',
alpha=.5, animated=True, lw=8)
# puck (s)
self.puckdisp = self.ax.scatter([1], [1], label='_nolegend_',
s=200, c='g',
alpha=.9, animated=True)
self.canvas = self.ax.figure.canvas
self.background = None
self.cnt = 0
self.distract = True
self.res = 100.0
self.on = False
self.inst = True # show instructions from the beginning
self.pads = [Pad(pA, pad_a_x, pad_a_y),
Pad(pB, pad_b_x, pad_b_y, 'r')]
self.pucks = []
self.i = self.ax.annotate(instructions, (.5, 0.5),
name='monospace',
verticalalignment='center',
horizontalalignment='center',
multialignment='left',
xycoords='axes fraction',
animated=False)
self.canvas.mpl_connect('key_press_event', self.on_key_press)
def draw(self):
draw_artist = self.ax.draw_artist
if self.background is None:
self.background = self.canvas.copy_from_bbox(self.ax.bbox)
# restore the clean slate background
self.canvas.restore_region(self.background)
# show the distractors
if self.distract:
self.line.set_ydata(np.sin(self.x + self.cnt/self.res))
self.line2.set_ydata(np.cos(self.x - self.cnt/self.res))
self.line3.set_ydata(np.tan(self.x + self.cnt/self.res))
self.line4.set_ydata(np.tan(self.x - self.cnt/self.res))
draw_artist(self.line)
draw_artist(self.line2)
draw_artist(self.line3)
draw_artist(self.line4)
# pucks and pads
if self.on:
self.ax.draw_artist(self.centerline)
for pad in self.pads:
pad.disp.set_y(pad.y)
pad.disp.set_x(pad.x)
self.ax.draw_artist(pad.disp)
for puck in self.pucks:
if puck.update(self.pads):
# we only get here if someone scored
self.pads[0].disp.set_label(
" " + str(self.pads[0].score))
self.pads[1].disp.set_label(
" " + str(self.pads[1].score))
self.ax.legend(loc='center', framealpha=.2,
facecolor='0.5',
prop=FontProperties(size='xx-large',
weight='bold'))
self.background = None
self.ax.figure.canvas.draw_idle()
return
puck.disp.set_offsets([[puck.x, puck.y]])
self.ax.draw_artist(puck.disp)
# just redraw the axes rectangle
self.canvas.blit(self.ax.bbox)
self.canvas.flush_events()
if self.cnt == 50000:
# just so we don't get carried away
print("...and you've been playing for too long!!!")
plt.close()
self.cnt += 1
def on_key_press(self, event):
if event.key == '3':
self.res *= 5.0
if event.key == '4':
self.res /= 5.0
if event.key == 'e':
self.pads[0].y += .1
if self.pads[0].y > 1 - .3:
self.pads[0].y = 1 - .3
if event.key == 'd':
self.pads[0].y -= .1
if self.pads[0].y < -1:
self.pads[0].y = -1
if event.key == 'i':
self.pads[1].y += .1
if self.pads[1].y > 1 - .3:
self.pads[1].y = 1 - .3
if event.key == 'k':
self.pads[1].y -= .1
if self.pads[1].y < -1:
self.pads[1].y = -1
if event.key == 'a':
self.pucks.append(Puck(self.puckdisp,
self.pads[randint(2)],
self.ax.bbox))
if event.key == 'A' and len(self.pucks):
self.pucks.pop()
if event.key == ' ' and len(self.pucks):
self.pucks[0]._reset(self.pads[randint(2)])
if event.key == '1':
for p in self.pucks:
p._slower()
if event.key == '2':
for p in self.pucks:
p._faster()
if event.key == 'n':
self.distract = not self.distract
if event.key == 'g':
self.on = not self.on
if event.key == 't':
self.inst = not self.inst
self.i.set_visible(not self.i.get_visible())
self.background = None
self.canvas.draw_idle()
if event.key == 'q':
plt.close()
fig, ax = plt.subplots()
canvas = ax.figure.canvas
animation = Game(ax)
# disable the default key bindings
if fig.canvas.manager.key_press_handler_id is not None:
canvas.mpl_disconnect(fig.canvas.manager.key_press_handler_id)
# reset the blitting background on redraw
def on_redraw(event):
animation.background = None
# bootstrap after the first draw
def start_anim(event):
canvas.mpl_disconnect(start_anim.cid)
start_anim.timer.add_callback(animation.draw)
start_anim.timer.start()
canvas.mpl_connect('draw_event', on_redraw)
start_anim.cid = canvas.mpl_connect('draw_event', start_anim)
start_anim.timer = animation.canvas.new_timer(interval=1)
tstart = time.time()
plt.show()
print('FPS: %f' % (animation.cnt/(time.time() - tstart)))