Box2D v2.2.0用户手册：游戏物理引擎详解

需积分: 0 44 浏览量更新于2024-07-28 收藏 1.15MB PDF 举报

Box2D v2.2.0用户手册是一份全面介绍Box2D物理引擎的文档，由Erin Catto创作，版权时间为2007年至2011年。该引擎专为游戏设计，旨在为游戏世界增添逼真的物体运动和互动性，将其视为游戏引擎中的一个用于程序化动画的系统。Box2D是用可移植的C++编写的，所有在引擎中定义的类型都带有前缀“b2”，以减少与游戏引擎自身命名冲突的可能性。手册的第1章为介绍，它首先概述了Box2D的主要用途，即模拟2D刚体，使程序员能够创建动态的游戏对象并增强游戏体验。作者假设读者对基本物理概念有所了解，包括质量、力、扭矩和冲量，如果读者对此不熟悉，建议先查阅Google搜索和维基百科进行学习。接下来的章节详细介绍了Box2D的各个模块： - 第2章"Hello Box2D"提供了一个简单的入门示例，让读者快速上手。 - 第3章"Common"涵盖了引擎的基础设置和通用功能。 - 第4章"Collision Module"深入讲解碰撞检测和处理，这对于构建游戏对象之间的交互至关重要。 - 第5章"Dynamics Module"涉及物体的动力学行为，包括力、速度和加速度的管理。 - 第6章"Fixtures"讨论了如何创建和配置游戏对象的形状，即fixture（固定物体）。 - 第7章"Bodies"着重于body（刚体）的概念，这是物理模拟的核心元素。 - 第8章"Joints"介绍连接两个或多个body的关节，如铰链、滑轮等，以实现复杂的行为。 - 第9章"Contacts"探讨接触点的处理，包括摩擦力和弹性碰撞。 - 第10章"World Class"涵盖了世界设置和管理，如重力、步进和时间控制。 - 第11章"Loose Ends"可能包含了一些额外的实用技巧和未涵盖的小细节。 - 第12章"Debug Drawing"提供了调试工具，帮助开发者可视化物理模拟。 - 最后，第13章"Limitations"列出了引擎的限制和潜在问题，以及如何应对。通过阅读这本手册，开发者不仅能掌握Box2D的基本使用方法，还能深入了解其内部工作原理，以便更好地应用于他们的游戏项目中。

float32 timeStep = 1.0f / 60.0f;

In addition to the integrator, Box2D also uses a larger bit of code called a constraint solver. The

constraint solver solves all the constraints in the simulation, one at a time. A single constraint can be

solved perfectly. However, when we solve one constraint, we slightly disrupt other constraints. To get a

good solution, we need to iterate over all constraints a number of times.

There are two phases in the constraint solver: a velocity phase and a position phase. In the velocity

phase the solver computes the impulses necessary for the bodies to move correctly. In the position

phase the solver adjusts the positions of the bodies to reduce overlap and joint detachment. Each phase

has its own iteration count. In addition, the position phase may exit iterations early if the errors are

small.

The suggested iteration count for Box2D is 8 for velocity and 3 for position. You can tune this number to

your liking, just keep in mind that this has a trade-off between speed and accuracy. Using fewer

iterations increases performance but accuracy suffers. Likewise, using more iterations decreases

performance but improves the quality of your simulation. For this simple example, we don't need much

iteration. Here are our chosen iteration counts.

int32 velocityIterations = 6;

int32 positionIterations = 2;

Note that the time step and the iteration count are completely unrelated. An iteration is not a sub-step.

One solver iteration is a single pass over all the constraints within a time step. You can have multiple

passes over the constraints within a single time step.

We are now ready to begin the simulation loop. In your game the simulation loop can be merged with

your game loop. In each pass through your game loop you call b2World::Step. Just one call is usually

enough, depending on your frame rate and your physics time step.

The Hello World program was designed to be simple, so it has no graphical output. The code prints out

the position and rotation of the dynamic body. Here is the simulation loop that simulates 60 time steps

for a total of 1 second of simulated time.

for (int32 i = 0; i < 60; ++i)

{

world.Step(timeStep, velocityIterations, positionIterations);

b2Vec2 position = body->GetPosition();

float32 angle = body->GetAngle();

printf("%4.2f %4.2f %4.2f\n", position.x, position.y, angle);

}

The output shows the box falling and landing on the ground box. Your output should look like this:

剩余65页未读，继续阅读

tsr106

粉丝: 10
资源: 25

Box2D v2.2.0用户手册：游戏物理引擎详解

Box2D源码整合与PDF版

Box2D的C#移植版本Box2D .NET Standard发布

Box2D.go - Go语言版的Box2D物理引擎

box2d_manual_cn.pdf

Introduction to Game Physics with Box2D 无水印pdf

box2d_manual_cn

box2d中文教程pdf

Box2D_Lite.rar_Box2D Lite e_Box2D_Lite_box2D

Box2D_02_碰撞_box2D安卓快写代码_box2D_box2d碰撞_

box2d中文教程.pdf

最新资源