#!/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)