1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
#!/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
#
# 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.
# Ported from the Cloth test by Paril, originally for Box2CS:
# http://www.box2d.org/forum/viewtopic.php?f=6&t=6124
#
from .framework import (Framework, Keys, main)
from Box2D import (b2CircleShape, b2FixtureDef, b2Random, b2Vec2)
def create_cloth(world, segment_count, body_size, position=(0, 30),
group_index=-1, bar_height=0.5, base_hz=15,
base_damping=0.11, density=0.2):
segment_w, segment_h = segment_count
body_spacing_w = body_size * 2
total_w = body_spacing_w * segment_w
position = b2Vec2(*position)
# The static bar at the top which holds the cloth
bar = world.CreateStaticBody(position=position)
bar.CreatePolygonFixture(box=(total_w / 2.0 + body_spacing_w,
bar_height / 2.0),
groupIndex=group_index)
box_fixture = b2FixtureDef(shape=b2CircleShape(radius=body_size),
groupIndex=group_index, density=density)
weld_joints = []
distance_joints = []
cloth = [[None] * segment_h for x in range(segment_w)]
for y in range(segment_h):
pos = position - (total_w / 2.0, y * body_spacing_w)
for x in range(segment_w):
pos += (body_spacing_w, 0.0)
body = world.CreateDynamicBody(position=pos, fixtures=box_fixture)
cloth[x][y] = body
if y == 0:
joint = world.CreateWeldJoint(bodyA=body, bodyB=bar,
anchor=body.position)
weld_joints.append(joint)
connect_bodies = []
for y in range(segment_h):
for x in range(segment_w):
if x <= segment_w - 2:
left_body = cloth[x][y]
right_body = cloth[x + 1][y]
connect_bodies.append((left_body, right_body))
if y > 0:
left_body = cloth[x][y]
right_body = cloth[x][y - 1]
connect_bodies.append((left_body, right_body))
for bodyA, bodyB in connect_bodies:
joint = world.CreateDistanceJoint(
bodyA=bodyA,
bodyB=bodyB,
anchorA=bodyA.position,
anchorB=bodyB.position,
frequencyHz=base_hz + b2Random(0, base_hz / 2.0),
dampingRatio=base_damping + b2Random(0.01, base_damping),
)
distance_joints.append(joint)
return cloth, weld_joints, distance_joints
def step_cloth(world, cloth, wind, body_size, segment_count, distance_joints,
wind_dir=(1, 1), wind_rand=0.0, distance_factor=1.45):
segment_w, segment_h = segment_count
body_spacing_w = body_size * 2
if wind:
for x in range(segment_w):
w = (b2Random(wind_dir[0] - wind_rand / 2.0,
wind_dir[0] + wind_rand / 2.0),
b2Random(wind_dir[1] - wind_rand / 2.0,
wind_dir[1] + wind_rand / 2.0))
cloth[x][-1].linearVelocity += w
# If any two points are too far from one another, find the joint connecting
# them and destroy it.
check_segments = []
for y in range(segment_h):
for x in range(segment_w):
if y > 0:
check_segments.append((cloth[x][y], cloth[x][y - 1]))
if x <= segment_w - 2:
check_segments.append((cloth[x][y], cloth[x + 1][y]))
thresh = body_spacing_w * distance_factor
for c1, c2 in check_segments:
if (c1.worldCenter - c2.worldCenter).length <= thresh:
continue
for joint in distance_joints:
if ((joint.bodyA == c1 and joint.bodyB == c2) or
(joint.bodyA == c2 and joint.bodyB == c1)):
world.DestroyJoint(joint)
distance_joints.remove(joint)
break
class Cloth(Framework):
name = "Cloth"
description = "(w) Toggle wind"
def __init__(self):
super(Cloth, self).__init__()
self.wind = False
self.segment_count = (18, 25)
self.body_size = 0.22
cloth_info = create_cloth(
self.world, self.segment_count, self.body_size)
self.cloth, self.weld_joints, self.dist_joints = cloth_info
def Keyboard(self, key):
if key == Keys.K_w:
self.wind = not self.wind
def Step(self, settings):
super(Cloth, self).Step(settings)
if self.wind:
self.Print('Wind enabled')
step_cloth(self.world, self.cloth, self.wind, self.body_size,
self.segment_count, self.dist_joints)
if __name__ == "__main__":
main(Cloth)
|
