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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 (b2CircleShape, b2EdgeShape, b2FixtureDef, b2PolygonShape,
b2_linearSlop)
class OneSidedPlatform (Framework):
name = "One-sided Platform"
description = ("Try to move the shape with the mouse through the platform "
"from all directions")
def __init__(self):
super(OneSidedPlatform, self).__init__()
# The ground
ground = self.world.CreateBody(
shapes=b2EdgeShape(vertices=[(-20, 0), (20, 0)])
)
# The platform
half_height = 0.5
ypos = 10
body = self.world.CreateBody(
position=(0, ypos),
shapes=b2PolygonShape(box=(3, half_height))
)
self.platform = body.fixtures[0]
# The circular character
self.character_radius = 0.5
body = self.world.CreateDynamicBody(
position=(0, 12),
fixtures=b2FixtureDef(shape=b2CircleShape(
radius=self.character_radius), density=1.0),
)
self.character = body.fixtures[0]
body.linearVelocity = (0, -50)
self.bottom = ypos - half_height # The bottom of the platform
self.top = ypos + half_height # The top of the platform
self.state = 'unknown'
def PreSolve(self, contact, oldManifold):
super(OneSidedPlatform, self).PreSolve(contact, oldManifold)
# Make sure we're dealing with the platform and the character
if (contact.fixtureA != self.platform and
contact.fixtureA != self.character):
return
if (contact.fixtureB != self.platform and
contact.fixtureB != self.character):
return
# If below the top of the platform, disable the collision response
pos = (self.character.body.position.y - self.character_radius +
3.0 * b2_linearSlop)
if pos < self.top:
contact.enabled = False
if __name__ == "__main__":
main(OneSidedPlatform)
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