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
|
// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include "box2d/box2d.h"
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"
#include <stdio.h>
// This is a simple example of building and running a simulation
// using Box2D. Here we create a large ground box and a small dynamic
// box.
// There are no graphics for this example. Box2D is meant to be used
// with your rendering engine in your game engine.
DOCTEST_TEST_CASE("hello world")
{
// Define the gravity vector.
b2Vec2 gravity(0.0f, -10.0f);
// Construct a world object, which will hold and simulate the rigid bodies.
b2World world(gravity);
// Define the ground body.
b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0.0f, -10.0f);
// Call the body factory which allocates memory for the ground body
// from a pool and creates the ground box shape (also from a pool).
// The body is also added to the world.
b2Body* groundBody = world.CreateBody(&groundBodyDef);
// Define the ground box shape.
b2PolygonShape groundBox;
// The extents are the half-widths of the box.
groundBox.SetAsBox(50.0f, 10.0f);
// Add the ground fixture to the ground body.
groundBody->CreateFixture(&groundBox, 0.0f);
// Define the dynamic body. We set its position and call the body factory.
b2BodyDef bodyDef;
bodyDef.type = b2_dynamicBody;
bodyDef.position.Set(0.0f, 4.0f);
b2Body* body = world.CreateBody(&bodyDef);
// Define another box shape for our dynamic body.
b2PolygonShape dynamicBox;
dynamicBox.SetAsBox(1.0f, 1.0f);
// Define the dynamic body fixture.
b2FixtureDef fixtureDef;
fixtureDef.shape = &dynamicBox;
// Set the box density to be non-zero, so it will be dynamic.
fixtureDef.density = 1.0f;
// Override the default friction.
fixtureDef.friction = 0.3f;
// Add the shape to the body.
body->CreateFixture(&fixtureDef);
// Prepare for simulation. Typically we use a time step of 1/60 of a
// second (60Hz) and 10 iterations. This provides a high quality simulation
// in most game scenarios.
float timeStep = 1.0f / 60.0f;
int32 velocityIterations = 6;
int32 positionIterations = 2;
b2Vec2 position = body->GetPosition();
float angle = body->GetAngle();
// This is our little game loop.
for (int32 i = 0; i < 60; ++i)
{
// Instruct the world to perform a single step of simulation.
// It is generally best to keep the time step and iterations fixed.
world.Step(timeStep, velocityIterations, positionIterations);
// Now print the position and angle of the body.
position = body->GetPosition();
angle = body->GetAngle();
printf("%4.2f %4.2f %4.2f\n", position.x, position.y, angle);
}
// When the world destructor is called, all bodies and joints are freed. This can
// create orphaned pointers, so be careful about your world management.
CHECK(b2Abs(position.x) < 0.01f);
CHECK(b2Abs(position.y - 1.01f) < 0.01f);
CHECK(b2Abs(angle) < 0.01f);
}
|
