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#!/usr/bin/python
#
# Original C++ version by Daid
# http://www.box2d.org/forum/viewtopic.php?f=3&t=1473
#
# 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 *
class BoxCutter (Framework):
name="BoxCutter"
laserBody=None
_pickle_vars=['laserBody']
def __init__(self):
super(BoxCutter, self).__init__()
self.world.GetGroundBody().SetUserData("ground")
bd=box2d.b2BodyDef()
bd.position = (0.0, -10.0)
bd.userData = "ground1"
ground = self.world.CreateBody(bd)
sd=box2d.b2PolygonDef()
sd.SetAsBox(50.0, 10.0)
ground.CreateShape(sd)
bd=box2d.b2BodyDef()
bd.position = (0.0, 50.0)
bd.userData = "ground2"
ground = self.world.CreateBody(bd)
sd=box2d.b2PolygonDef()
sd.SetAsBox(50.0, 10.0)
ground.CreateShape(sd)
bd=box2d.b2BodyDef()
bd.position = (0.0, 1.0)
bd.userData = "laser"
self.laserBody = self.world.CreateBody(bd)
sd=box2d.b2PolygonDef()
sd.SetAsBox(5.0, 1.0)
sd.density = 4.0
self.laserBody.CreateShape(sd)
self.laserBody.SetMassFromShapes()
sd=box2d.b2PolygonDef()
sd.SetAsBox(3.0, 3.0)
sd.density = 5.0
bd=box2d.b2BodyDef()
bd.userData = 1
bd.position = (0.0, 8.0)
body1 = self.world.CreateBody(bd)
body1.CreateShape(sd)
body1.SetMassFromShapes()
sd=box2d.b2PolygonDef()
sd.SetAsBox(3.0, 3.0)
sd.density = 5.0
bd=box2d.b2BodyDef()
bd.userData = 1
bd.position = (0.0, 8.0)
body1 = self.world.CreateBody(bd)
body1.CreateShape(sd)
body1.SetMassFromShapes()
# Split a shape through a segment
# Returns:
# False - Error on split
# True - Normal result is two new shape definitions.
def SplitShape(self, shape, segment, splitSize, newPolygon):
b = shape.GetBody()
xf = b.GetXForm()
hit,lambda_,normal=shape.TestSegment(xf, segment, 1.0)
if hit != box2d.e_hitCollide:
return False
entryPoint = (1-lambda_)*segment.p1+lambda_*segment.p2
reverseSegment=box2d.b2Segment()
reverseSegment.p1=segment.p2
reverseSegment.p2=segment.p1
hit,lambda_,normal=shape.TestSegment(xf, reverseSegment, 1.0)
if hit != box2d.e_hitCollide:
return False
exitPoint = (1-lambda_)*reverseSegment.p1+lambda_*reverseSegment.p2
localEntryPoint = b.GetLocalPoint(entryPoint)
localExitPoint = b.GetLocalPoint(exitPoint)
vertices = shape.getVertices_b2Vec2()
cutAdded = [-1,-1]
last = -1
for i in range(shape.GetVertexCount()):
#Find out if this vertex is on the old or new shape.
if box2d.b2Dot(box2d.b2Cross(localExitPoint-localEntryPoint, 1), vertices[i]-localEntryPoint) > 0:
n = 0
else:
n = 1
if last != n:
#If we switch from one shape to the other add the cut vertices.
if last == 0:
assert(cutAdded[0]==-1)
cutAdded[0] = newPolygon[last].vertexCount
newPolygon[last].setVertex(newPolygon[last].vertexCount, localExitPoint)
newPolygon[last].vertexCount+=1
newPolygon[last].setVertex(newPolygon[last].vertexCount, localEntryPoint)
newPolygon[last].vertexCount+=1
elif last == 1:
assert(cutAdded[last]==-1)
cutAdded[last] = newPolygon[last].vertexCount
newPolygon[last].setVertex(newPolygon[last].vertexCount, localEntryPoint)
newPolygon[last].vertexCount+=1
newPolygon[last].setVertex(newPolygon[last].vertexCount, localExitPoint)
newPolygon[last].vertexCount+=1
newPolygon[n].setVertex(newPolygon[n].vertexCount, vertices[i])
newPolygon[n].vertexCount+=1
last = n
#Add the cut in case it has not been added yet.
if cutAdded[0]==-1:
cutAdded[0] = newPolygon[0].vertexCount
newPolygon[0].setVertex(newPolygon[0].vertexCount, localExitPoint)
newPolygon[0].vertexCount+=1
newPolygon[0].setVertex(newPolygon[0].vertexCount, localEntryPoint)
newPolygon[0].vertexCount+=1
if cutAdded[1]==-1:
cutAdded[1] = newPolygon[1].vertexCount
newPolygon[1].setVertex(newPolygon[1].vertexCount, localEntryPoint)
newPolygon[1].vertexCount+=1
newPolygon[1].setVertex(newPolygon[1].vertexCount, localExitPoint)
newPolygon[1].vertexCount+=1
# Cut based on the split size
for n in range(2):
if cutAdded[n] > 0:
offset = newPolygon[n].getVertex(cutAdded[n]-1) - newPolygon[n].getVertex(cutAdded[n])
else:
offset = newPolygon[n].getVertex(newPolygon[n].vertexCount-1) - newPolygon[n].getVertex(0)
offset.Normalize()
newPolygon[n].setVertex(cutAdded[n], newPolygon[n].getVertex(cutAdded[n]) + splitSize * offset)
if cutAdded[n] < newPolygon[n].vertexCount-2:
offset = newPolygon[n].getVertex(cutAdded[n]+2) - newPolygon[n].getVertex(cutAdded[n]+1)
else:
offset = newPolygon[n].getVertex(0) - newPolygon[n].getVertex(newPolygon[n].vertexCount-1)
offset.Normalize()
newPolygon[n].setVertex(cutAdded[n]+1, newPolygon[n].getVertex(cutAdded[n]+1) + splitSize * offset)
#Check if the new shapes are not too tiny.
for n in range(2):
for i in range(newPolygon[n].vertexCount):
for j in range(newPolygon[n].vertexCount):
if i != j and (newPolygon[n].getVertex(i) - newPolygon[n].getVertex(j)).Length() < 0.1:
return False
# Make sure the shapes are valid before creation
try:
for n in range(2):
box2d.b2CheckPolygonDef(newPolygon[n])
except ValueError, s:
print "Created bad shape:", s
return False
return True
def Cut(self):
segmentLength = 30.0
segment=box2d.b2Segment()
laserStart=(5.0-0.1,0.0)
laserDir =(segmentLength,0.0)
segment.p1 = self.laserBody.GetWorldPoint(laserStart)
segment.p2 = segment.p1 + self.laserBody.GetWorldVector(laserDir)
max_shapes = 64
count, shapes = self.world.Raycast(segment, max_shapes, False, None)
for i in range(count):
#Make sure it's a polygon, we cannot cut circles.
if shapes[i].GetType() != box2d.e_polygonShape:
continue
polyShape = shapes[i].getAsType()
b = polyShape.GetBody()
#Custom check to make sure we don't cut stuff we don't want to cut.
if b.GetUserData() != 1:
continue #return if we cannot pass trough uncutable shapes.
pd=[box2d.b2PolygonDef(),box2d.b2PolygonDef()]
pd[0].density = 5.0
pd[1].density = 5.0
if self.SplitShape(polyShape, segment, 0.1, pd):
b.DestroyShape(shapes[i])
b.CreateShape(pd[0])
b.SetMassFromShapes()
b.WakeUp()
bd=box2d.b2BodyDef()
bd.userData = 1
bd.position = b.GetPosition()
bd.angle = b.GetAngle()
newBody = self.world.CreateBody(bd)
newBody.CreateShape(pd[1])
newBody.SetMassFromShapes()
newBody.SetAngularVelocity(b.GetAngularVelocity())
newBody.SetLinearVelocity(b.GetLinearVelocity())
def Keyboard(self, key):
if key==K_c:
self.Cut()
def Step(self, settings):
super(BoxCutter, self).Step(settings)
if not self.laserBody:
return
self.DrawStringCR("Keys: Cut = c")
segmentLength = 30.0
segment=box2d.b2Segment()
laserStart=(5.0-0.1,0.0)
laserDir =(segmentLength,0.0)
segment.p1 = self.laserBody.GetWorldPoint(laserStart)
segment.p2 = segment.p1+self.laserBody.GetWorldVector(laserDir)
laserColor=box2d.b2Color(1,0,0)
self.debugDraw.DrawSegment(segment.p1,segment.p2,laserColor)
if __name__=="__main__":
main(BoxCutter)
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