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Lua Game Development Cookbook

By : Mario Kasuba, Mário Kašuba
Book Image

Lua Game Development Cookbook

By: Mario Kasuba, Mário Kašuba

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Lua Game Development Cookbook
Mario Kasuba | Mário Kašuba
Jul, 2015 | 360 pages
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Table of Contents (16 chapters)
Lua Game Development Cookbook
Lua Game Development Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Basics of the Game Engine
Basics of the Game Engine
Introduction
Preparing a basic file structure for the game engine
Making a stack
Making a queue
Making a prioritized queue
Extending ipairs for use in sparse arrays
Creating Lua modules
Handling errors with pcall, xpcall, and assert
Using Lua with existing projects written in C/C++
Getting LuaSDL for libSDL 1.2
Designing the main application loop with LuaSDL
2
Events
Events
Introduction
Processing input events with LuaSDL
Using the keyboard input
Using the relative mouse position
Using the absolute mouse position
Using timers
3
Graphics – Common Methods
Graphics – Common Methods
Introduction
Creating a window in libSDL
Creating surfaces
Surfaces manipulation
Using colors
Cursor manipulation
Initializing the graphics mode with OpenGL
Getting OpenGL information
Using OpenGL extensions with GLEW and Lua
Loading images with SDL_image
Creating textures
Loading and using bitmap fonts
Loading and using TrueType fonts
Displaying the text
Creating texture atlas with the rover-design pattern
Using tiles and tilesets in the game
4
Graphics – Legacy Method with OpenGL 1.x–2.1
Graphics – Legacy Method with OpenGL 1.x–2.1
Introduction
Drawing primitives in immediate mode
Setting up blending
Moving, rotating, and scaling objects
Setting up the orthogonal and perspective cameras
Setting up materials
Setting up lighting
Using display lists
Setting up the vertex buffer
5
Graphics – Modern Method with OpenGL 3.0+
Graphics – Modern Method with OpenGL 3.0+
Introduction
Loading and using GLSL shaders
Using uniform variables with shaders
Writing a vertex shader
Writing a fragment (pixel) shader
Drawing primitives using vertex buffers
Rendering to texture
Applying highlights and shadows to the scene
Bumpmapping
6
The User Interface
The User Interface
Introduction
Drawing a simple window
Moving the window
Using the window hierarchy
Showing the part of the window with the stencil test and window content scrolling
Window controls and interaction
7
Physics and Game Mechanics
Physics and Game Mechanics
Introduction
Using Box2D with Lua
Using vector math
Choosing the correct vector scaling for the physics engine
Creating static and dynamic objects
Setting up object properties
Moving objects
Setting up bullets
Running the physics simulation
Detecting object collision
Setting up object collision filtering
Setting up object joints
8
Artificial Intelligence
Artificial Intelligence
Introduction
A simple pathfinding algorithm for a maze
Pathfinding for tile-based environments with obstacles
Using a fuzzy logic for decision making
9
Sounds and Networking
Sounds and Networking
Introduction
Initializing the audio subsystem
Playing sound samples
Playing background music
Network communication with ZeroMQ
Creating a basic client-server architecture
Sending messages to many hosts at once
Communication between threads
Index
Index

Choosing the correct vector scaling for the physics engine

The Box2D library uses floating numbers to represent numerical values. The problem with these kind of numbers is that they offer limited precision. This limitation often results in various artefacts such as players walking right above the ground or boxes that can't remain in one place. Box2D uses the MKS (meters, kilograms, and seconds) system to represent the basic units. You should never use a pixel as a base unit. Therefore, you are expected to use the scaling factor to convert Box2D coordinates to pixels on the screen.

Getting ready

First, you should decide what scaling factor you will use. If you decide that 100 pixels will represent 1 meter, the scaling factor will be 100. You can define this factor as a global constant in the Lua language:

box2dScalingFactor = 100

How to do it…

When converting pixel-sized objects or vectors to the Box2D system, the scaling factor will be used to scale down by dividing all those values. The following...

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