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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 by Ken Lauer / 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, main)
from Box2D import (b2EdgeShape, b2FixtureDef, b2PolygonShape)
class ConveyorBelt (Framework):
name = "ConveyorBelt"
def __init__(self):
Framework.__init__(self)
self.using_contacts = True
ground = self.world.CreateStaticBody(
shapes=[b2EdgeShape(vertices=[(-20, 0), (20, 0)])],
)
# Platform
self.platform = self.world.CreateStaticBody(
position=(-5, 5),
allowSleep=False,
fixtures=b2FixtureDef(friction=0.8,
shape=b2PolygonShape(box=(10.0, 5.0)),),
)
self.platform_fixture = self.platform.fixtures[0]
# Boxes
for i in range(5):
self.platform = self.world.CreateDynamicBody(
position=(-10.0 + 2.0 * i, 7.0),
fixtures=b2FixtureDef(density=20.0,
shape=b2PolygonShape(box=(0.5, 0.5)),),
)
def PreSolve(self, contact, old_manifold):
Framework.PreSolve(self, contact, old_manifold)
fixture_a, fixture_b = contact.fixtureA, contact.fixtureB
if fixture_a == self.platform_fixture:
contact.tangentSpeed = 5.0
elif fixture_b == self.platform_fixture:
contact.tangentSpeed = -5.0
if __name__ == "__main__":
main(ConveyorBelt)
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