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#!/usr/bin/python
#
# C++ version Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
# Python version Copyright (c) 2008 kne / sirkne at gmail dot com
#
# Implemented using the pybox2d SWIG interface for Box2D (pybox2d.googlecode.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 test_main import *
# A motor driven slider crank with joint friction.
class SliderCrank (Framework):
name="SliderCrank"
joint1=None
joint2=None
_pickle_vars=['joint1', 'joint2']
def __init__(self):
super(SliderCrank, self).__init__()
sd=box2d.b2PolygonDef()
sd.SetAsBox(50.0, 10.0)
bd=box2d.b2BodyDef()
bd.position = (0.0, -10.0)
ground = self.world.CreateBody(bd)
ground.CreateShape(sd)
# Define crank.
sd=box2d.b2PolygonDef()
sd.SetAsBox(0.5, 2.0)
sd.density = 1.0
rjd=box2d.b2RevoluteJointDef()
prevBody=ground
bd=box2d.b2BodyDef()
bd.position = (0.0, 7.0)
body = self.world.CreateBody(bd)
body.CreateShape(sd)
body.SetMassFromShapes()
rjd.Initialize(prevBody, body, (0.0, 5.0))
rjd.motorSpeed = 1.0 * box2d.b2_pi
rjd.maxMotorTorque = 10000.0
rjd.enableMotor = True
self.joint1 = self.world.CreateJoint(rjd).getAsType()
prevBody = body
# Define follower.
sd.SetAsBox(0.5, 4.0)
bd.position = (0.0, 13.0)
body = self.world.CreateBody(bd)
body.CreateShape(sd)
body.SetMassFromShapes()
rjd.Initialize(prevBody, body, (0.0, 9.0))
rjd.enableMotor = False
self.world.CreateJoint(rjd).getAsType()
prevBody = body
# Define piston
sd.SetAsBox(1.5, 1.5)
bd.position = (0.0, 17.0)
body = self.world.CreateBody(bd)
body.CreateShape(sd)
body.SetMassFromShapes()
rjd.Initialize(prevBody, body, (0.0, 17.0))
self.world.CreateJoint(rjd).getAsType()
pjd=box2d.b2PrismaticJointDef()
pjd.Initialize(ground, body, (0.0, 17.0), (0.0, 1.0))
pjd.maxMotorForce = 1000.0
pjd.enableMotor = True
self.joint2 = self.world.CreateJoint(pjd).getAsType()
# Create a payload
sd.density = 2.0
bd.position = (0.0, 23.0)
body = self.world.CreateBody(bd)
body.CreateShape(sd)
body.SetMassFromShapes()
def Keyboard(self, key):
if not self.joint1 or not self.joint2:
return
if key==K_f:
self.joint2.enableMotor = not self.joint2.enableMotor
self.joint2.GetBody2().WakeUp()
elif key==K_m:
self.joint1.enableMotor = not self.joint1.enableMotor
self.joint1.GetBody2().WakeUp()
def Step(self, settings):
self.DrawStringCR("Keys: (f) toggle friction, (m) toggle motor")
if self.joint1:
torque = self.joint1.GetMotorTorque()
self.DrawStringCR("Motor Torque = %.0f" % (torque))
super(SliderCrank, self).Step(settings)
if __name__=="__main__":
main(SliderCrank)
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