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"""
This file is part of the 'Elements' Project
Elements is a 2D Physics API for Python (supporting Box2D2)
Copyright (C) 2008, The Elements Team, <elements@linuxuser.at>
Home: http://elements.linuxuser.at
IRC: #elements on irc.freenode.org
Code: http://www.assembla.com/wiki/show/elements
svn co http://svn2.assembla.com/svn/elements
License: GPLv3 | See LICENSE for the full text
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
from locals import *
from elements import box2d
class CallbackHandler:
# List of contact callbacks and shapes to start them - sorted by type for quicker access
# Callbacks are saved as callbacks[callback_type][[function, parameters], ...]
callbacks = {}
def __init__(self, parent):
self.parent = parent
# init callback dict to avoid those slow try
# (especially for self.get, as it is called *often*)
for i in xrange(10):
self.callbacks[i] = []
def add(self, callback_type, callback_handler, *args):
""" Users can add callbacks for certain (or all) collisions
Parameters:
callback_type ......... CALLBACK_CONTACT (nothing else for now)
callback_handler ...... a callback function
args (optional) ....... a list of parameters which can be used with callbacks.get
Return:
callback_id ... used to remove a callback later (int)
"""
# Create contact listener if required
if callback_type in [CALLBACK_CONTACT_ADD, CALLBACK_CONTACT_PERSIST, CALLBACK_CONTACT_REMOVE]:
if self.parent.klistener == None:
self.parent.klistener = kContactListener(self.get)
self.parent.world.SetContactListener( self.parent.klistener )
print "* kContactListener added"
# Get callback dict for this callback_type
c = self.callbacks[callback_type]
# Append to the Callback Dictionary
c.append([callback_handler, args])
self.callbacks[callback_type] = c
# Return Callback ID
# ID = callback_type.callback_index (1...n)
return "%i.%i" % (callback_type, len(c))
def get(self, callback_type):
return self.callbacks[callback_type]
def start(self, callback_type, *args):
callbacks = self.get(callback_type)
for c in callbacks:
callback, params = c
callback()
class kContactListener(box2d.b2ContactListener):
def __init__(self, get_callbacks):
# Init the Box2D b2ContactListener
box2d.b2ContactListener.__init__(self)
# Function to get the current callbacks
self.get_callbacks = get_callbacks
def check_contact(self, contact_type, point):
# Checks if a callback should be started with this contact point
contacts = self.get_callbacks(contact_type)
# Step through all callbacks for this type (eg ADD, PERSIST, REMOVE)
for c in contacts:
callback, bodylist = c
if len(bodylist) == 0:
# Without bodylist it's a universal callback (for all bodies)
callback(point)
else:
# This is a callback with specified bodies
# See if this contact involves one of the specified
b1 = str(point.shape1.GetBody())
b2 = str(point.shape2.GetBody())
for s in bodylist:
s = str(s)
if b1 == s or b2 == s:
# Yes, that's the one :)
callback(point)
def Add(self, point):
"""Called when a contact point is created"""
self.check_contact(CALLBACK_CONTACT_ADD, point)
def Persist(self, point):
"""Called when a contact point persists for more than a time step"""
self.check_contact(CALLBACK_CONTACT_PERSIST, point)
def Remove(self, point):
"""Called when a contact point is removed"""
self.check_contact(CALLBACK_CONTACT_REMOVE, point)
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