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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# C++ version Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
# Python version Copyright (c) 2010 kne / sirkne at gmail dot com
#
# This software is provided 'as-is', without any express or implied
# warranty. In no event will the authors be held liable for any damages
# arising from the use of this software.
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
# 1. The origin of this software must not be misrepresented; you must not
# claim that you wrote the original software. If you use this software
# in a product, an acknowledgment in the product documentation would be
# appreciated but is not required.
# 2. Altered source versions must be plainly marked as such, and must not be
# misrepresented as being the original software.
# 3. This notice may not be removed or altered from any source distribution.
from .framework import (Framework, Keys, main)
from Box2D import (b2DistanceJointDef, b2EdgeShape, b2FixtureDef,
b2PolygonShape)
class Web(Framework):
name = "Web"
description = "This demonstrates a soft distance joint. Press: (b) to delete a body, (j) to delete a joint"
bodies = []
joints = []
def __init__(self):
super(Web, self).__init__()
# The ground
ground = self.world.CreateBody(
shapes=b2EdgeShape(vertices=[(-40, 0), (40, 0)])
)
fixture = b2FixtureDef(shape=b2PolygonShape(box=(0.5, 0.5)),
density=5, friction=0.2)
self.bodies = [self.world.CreateDynamicBody(
position=pos,
fixtures=fixture
) for pos in ((-5, 5), (5, 5), (5, 15), (-5, 15))]
bodies = self.bodies
# Create the joints between each of the bodies and also the ground
# bodyA bodyB localAnchorA localAnchorB
sets = [(ground, bodies[0], (-10, 0), (-0.5, -0.5)),
(ground, bodies[1], (10, 0), (0.5, -0.5)),
(ground, bodies[2], (10, 20), (0.5, 0.5)),
(ground, bodies[3], (-10, 20), (-0.5, 0.5)),
(bodies[0], bodies[1], (0.5, 0), (-0.5, 0)),
(bodies[1], bodies[2], (0, 0.5), (0, -0.5)),
(bodies[2], bodies[3], (-0.5, 0), (0.5, 0)),
(bodies[3], bodies[0], (0, -0.5), (0, 0.5)),
]
# We will define the positions in the local body coordinates, the length
# will automatically be set by the __init__ of the b2DistanceJointDef
self.joints = []
for bodyA, bodyB, localAnchorA, localAnchorB in sets:
dfn = b2DistanceJointDef(
frequencyHz=4.0,
dampingRatio=0.5,
bodyA=bodyA,
bodyB=bodyB,
localAnchorA=localAnchorA,
localAnchorB=localAnchorB,
)
self.joints.append(self.world.CreateJoint(dfn))
def Keyboard(self, key):
if key == Keys.K_b:
for body in self.bodies:
# Gets both FixtureDestroyed and JointDestroyed callbacks.
self.world.DestroyBody(body)
break
elif key == Keys.K_j:
for joint in self.joints:
# Does not get a JointDestroyed callback!
self.world.DestroyJoint(joint)
self.joints.remove(joint)
break
def FixtureDestroyed(self, fixture):
super(Web, self).FixtureDestroyed(fixture)
body = fixture.body
if body in self.bodies:
print(body)
self.bodies.remove(body)
print("Fixture destroyed, removing its body from the list. Bodies left: %d"
% len(self.bodies))
def JointDestroyed(self, joint):
if joint in self.joints:
self.joints.remove(joint)
print("Joint destroyed and removed from the list. Joints left: %d"
% len(self.joints))
if __name__ == "__main__":
main(Web)
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