1+ // SPDX-FileCopyrightText: 2025 Erin Catto
2+ // SPDX-FileCopyrightText: 2025 Ikpil Choi([email protected] ) 3+ // SPDX-License-Identifier: MIT
4+
5+ using System . Numerics ;
6+ using ImGuiNET ;
7+ using static Box2D . NET . B2Joints ;
8+ using static Box2D . NET . B2Geometries ;
9+ using static Box2D . NET . B2Types ;
10+ using static Box2D . NET . B2MathFunction ;
11+ using static Box2D . NET . B2Bodies ;
12+ using static Box2D . NET . B2Shapes ;
13+ using static Box2D . NET . B2Ids ;
14+
15+ namespace Box2D . NET . Samples . Samples . Issues ;
16+
17+ public class Crash01 : Sample
18+ {
19+ private static readonly int SampleBodyType = SampleFactory . Shared . RegisterSample ( "Issues" , "Crash01" , Create ) ;
20+
21+ private B2BodyId m_attachmentId ;
22+ private B2BodyId m_platformId ;
23+ private B2BodyType m_type ;
24+ private bool m_isEnabled ;
25+
26+ private static Sample Create ( SampleContext context )
27+ {
28+ return new Crash01 ( context ) ;
29+ }
30+
31+ public Crash01 ( SampleContext context ) : base ( context )
32+ {
33+ if ( m_context . settings . restart == false )
34+ {
35+ m_context . camera . m_center = new B2Vec2 ( 0.8f , 6.4f ) ;
36+ m_context . camera . m_zoom = 25.0f * 0.4f ;
37+ }
38+
39+ m_type = B2BodyType . b2_dynamicBody ;
40+ m_isEnabled = true ;
41+
42+ B2BodyId groundId = b2_nullBodyId ;
43+ {
44+ B2BodyDef bodyDef = b2DefaultBodyDef ( ) ;
45+ bodyDef . name = "ground" ;
46+ groundId = b2CreateBody ( m_worldId , ref bodyDef ) ;
47+
48+ B2Segment segment = new B2Segment ( new B2Vec2 ( - 20.0f , 0.0f ) , new B2Vec2 ( 20.0f , 0.0f ) ) ;
49+ B2ShapeDef shapeDef = b2DefaultShapeDef ( ) ;
50+ b2CreateSegmentShape ( groundId , ref shapeDef , ref segment ) ;
51+ }
52+
53+ // Define attachment
54+ {
55+ B2BodyDef bodyDef = b2DefaultBodyDef ( ) ;
56+ bodyDef . type = B2BodyType . b2_dynamicBody ;
57+ bodyDef . position = new B2Vec2 ( - 2.0f , 3.0f ) ;
58+ bodyDef . name = "attach1" ;
59+ m_attachmentId = b2CreateBody ( m_worldId , ref bodyDef ) ;
60+
61+ B2Polygon box = b2MakeBox ( 0.5f , 2.0f ) ;
62+ B2ShapeDef shapeDef = b2DefaultShapeDef ( ) ;
63+ shapeDef . density = 1.0f ;
64+ b2CreatePolygonShape ( m_attachmentId , ref shapeDef , ref box ) ;
65+ }
66+
67+ // Define platform
68+ {
69+ B2BodyDef bodyDef = b2DefaultBodyDef ( ) ;
70+ bodyDef . type = m_type ;
71+ bodyDef . isEnabled = m_isEnabled ;
72+ bodyDef . position = new B2Vec2 ( - 4.0f , 5.0f ) ;
73+ bodyDef . name = "platform" ;
74+ m_platformId = b2CreateBody ( m_worldId , ref bodyDef ) ;
75+
76+ B2Polygon box = b2MakeOffsetBox ( 0.5f , 4.0f , new B2Vec2 ( 4.0f , 0.0f ) , b2MakeRot ( 0.5f * B2_PI ) ) ;
77+
78+ B2ShapeDef shapeDef = b2DefaultShapeDef ( ) ;
79+ shapeDef . density = 2.0f ;
80+ b2CreatePolygonShape ( m_platformId , ref shapeDef , ref box ) ;
81+
82+ B2RevoluteJointDef revoluteDef = b2DefaultRevoluteJointDef ( ) ;
83+ B2Vec2 pivot = new B2Vec2 ( - 2.0f , 5.0f ) ;
84+ revoluteDef . @base . bodyIdA = m_attachmentId ;
85+ revoluteDef . @base . bodyIdB = m_platformId ;
86+ revoluteDef . @base . localFrameA . p = b2Body_GetLocalPoint ( m_attachmentId , pivot ) ;
87+ revoluteDef . @base . localFrameB . p = b2Body_GetLocalPoint ( m_platformId , pivot ) ;
88+ revoluteDef . maxMotorTorque = 50.0f ;
89+ revoluteDef . enableMotor = true ;
90+ b2CreateRevoluteJoint ( m_worldId , ref revoluteDef ) ;
91+
92+ B2PrismaticJointDef prismaticDef = b2DefaultPrismaticJointDef ( ) ;
93+ B2Vec2 anchor = new B2Vec2 ( 0.0f , 5.0f ) ;
94+ prismaticDef . @base . bodyIdA = groundId ;
95+ prismaticDef . @base . bodyIdB = m_platformId ;
96+ prismaticDef . @base . localFrameA . p = b2Body_GetLocalPoint ( groundId , anchor ) ;
97+ prismaticDef . @base . localFrameB . p = b2Body_GetLocalPoint ( m_platformId , anchor ) ;
98+ prismaticDef . maxMotorForce = 1000.0f ;
99+ prismaticDef . motorSpeed = 0.0f ;
100+ prismaticDef . enableMotor = true ;
101+ prismaticDef . lowerTranslation = - 10.0f ;
102+ prismaticDef . upperTranslation = 10.0f ;
103+ prismaticDef . enableLimit = true ;
104+
105+ b2CreatePrismaticJoint ( m_worldId , ref prismaticDef ) ;
106+ }
107+ }
108+
109+ public override void UpdateGui ( )
110+ {
111+ float fontSize = ImGui . GetFontSize ( ) ;
112+ float height = 11.0f * fontSize ;
113+ ImGui . SetNextWindowPos ( new Vector2 ( 0.5f * fontSize , m_camera . m_height - height - 2.0f * fontSize ) , ImGuiCond . Once ) ;
114+ ImGui . SetNextWindowSize ( new Vector2 ( 9.0f * fontSize , height ) ) ;
115+ ImGui . Begin ( "Crash 01" , ImGuiWindowFlags . NoMove | ImGuiWindowFlags . NoResize ) ;
116+
117+ if ( ImGui . RadioButton ( "Static" , m_type == B2BodyType . b2_staticBody ) )
118+ {
119+ m_type = B2BodyType . b2_staticBody ;
120+ b2Body_SetType ( m_platformId , B2BodyType . b2_staticBody ) ;
121+ }
122+
123+ if ( ImGui . RadioButton ( "Kinematic" , m_type == B2BodyType . b2_kinematicBody ) )
124+ {
125+ m_type = B2BodyType . b2_kinematicBody ;
126+ b2Body_SetType ( m_platformId , B2BodyType . b2_kinematicBody ) ;
127+ b2Body_SetLinearVelocity ( m_platformId , new B2Vec2 ( - 0.1f , 0.0f ) ) ;
128+ }
129+
130+ if ( ImGui . RadioButton ( "Dynamic" , m_type == B2BodyType . b2_dynamicBody ) )
131+ {
132+ m_type = B2BodyType . b2_dynamicBody ;
133+ b2Body_SetType ( m_platformId , B2BodyType . b2_dynamicBody ) ;
134+ }
135+
136+ if ( ImGui . Checkbox ( "Enable" , ref m_isEnabled ) )
137+ {
138+ if ( m_isEnabled )
139+ {
140+ b2Body_Enable ( m_attachmentId ) ;
141+ }
142+ else
143+ {
144+ b2Body_Disable ( m_attachmentId ) ;
145+ }
146+ }
147+
148+ ImGui . End ( ) ;
149+ }
150+ }
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