Variable scope – determining where a variable can be used
by Chris Dickinson, John P. Doran, Greg Lukosek
Unity 5: Learning C# by Developing Games
- Unity 5: Learning C# by Developing Games
- Table of Contents
- Unity 5: Learning C# by Developing Games
- Unity 5: Learning C# by Developing Games
- Credits
- Preface
- 1. Module 1
- 1. Discovering Your Hidden Scripting Skills and Getting Your Environment Ready
- Prerequisite knowledge to use this book
- Dealing with scriptphobia
- Downloading Unity
- Teaching behavior to GameObjects
- C# documentation – where to find it? Do I need it at all?
- Working with C# script files
- Creating a C# script file
- Introducing the MonoDevelop code editor
- Instance? What is it?
- Summary
- 2. Introducing the Building Blocks for Unity Scripts
- 3. Getting into the Details of Variables
- Writing C# statements properly
- Understanding component properties in Unity's Inspector
- Changing a property's value in the Inspector panel
- Private variables
- Naming your variables properly
- Beginning variable names with lowercase
- Using multiword variable names
- Declaring a variable and its type
- Assigning values while declaring a variable
- Where you declare a variable is important
- Variable scope – determining where a variable can be used
- Summary
- 4. Getting into the Details of Methods
- 5. Lists, Arrays, and Dictionaries
- 6. Loops
- 7. Object, a Container with Variables and Methods
- 8. Let's Make a Game! – From Idea to Development
- 9. Starting Your First Game
- 10. Writing GameManager
- 11. The Game Level
- 12. The User Interface
- 13. Collectables — What Next?
- 1. Discovering Your Hidden Scripting Skills and Getting Your Environment Ready
- 2. Module 2
- 01. 2D Twin-stick Shooter
- Project overview
- Setting up the project
- Creating our scene
- Implementing player movement
- Shooting behavior
- Creating enemies
- Adding GameController to spawn enemy waves
- Particle systems for enemy explosion
- Adding in sound effects/music
- Adding in points, score, and wave numbers
- Publishing the game
- Summary
- Challenges
- 2. Creating GUIs
- 3. GUIs Part 2 – Clicker Game
- 4. Mobile Endless Game – Procedural Content
- Project overview
- Prerequisites
- Project setup
- Adding the background
- Adding a simple animated character
- Making a repeating background
- Working with sorting layers
- Creating our player behaviour
- Creating obstacles
- Spawning obstacles at runtime
- Game start and end behaviours
- Keeping score
- Summary
- Challenges
- 5. Shooting Gallery – Working with Animations and Tweens
- 6. Side-scrolling Platformer
- 7. First Person Shooter Part 1 – Creating Exterior Environments
- 8. First-person Shooter Part 2 – Creating Interior Environments
- 9. First Person Shooter Part 3 – Implementing Gameplay and AI
- 10. Building an In-Game Level Editor
- 11. Finishing Touches
- 01. 2D Twin-stick Shooter
- 3. Module 3
- 1. Detecting Performance Issues
- 2. Scripting Strategies
- Cache Component references
- Obtaining Components using the fastest method
- Removing empty callback declarations
- Avoiding the Find() and SendMessage() methods at runtime
- Disabling unused scripts and objects
- Consider using distance-squared over distance
- Avoid retrieving string properties from GameObjects
- Update, Coroutines, and InvokeRepeating
- Consider caching Transform changes
- Faster GameObject null reference checks
- Summary
- 3. The Benefits of Batching
- 4. Kickstart Your Art
- Audio
- Loading audio files
- Encoding formats and quality levels
- Audio performance enhancements
- Minimize active Audio Source count
- Minimize Audio Clip references
- Enable Force to Mono for 3D sounds
- Resample to lower frequencies
- Consider all encoding formats
- Beware of streaming
- Apply Filter effects through Mixer groups to reduce duplication
- Use "WWW.audioClip" responsibly
- Consider Audio Module files for background music
- Texture files
- Mesh and animation files
- Summary
- Audio
- 5. Faster Physics
- Physics Engine internals
- Physics performance optimizations
- Scene setup
- Use Static Colliders appropriately
- Optimize the Collision Matrix
- Prefer discrete collision detection
- Modify the FixedUpdate frequency
- Adjust the Maximum Allowed Timestep
- Minimize cast and bounding-volume checks
- Avoid complex Mesh Colliders
- Avoid complex physics components
- Let physics objects sleep
- Modify Solver Iteration Count
- Optimizing ragdolls
- Know when to use physics
- Consider upgrading to Unity 5
- Summary
- 6. Dynamic Graphics
- Profiling rendering issues
- Front end bottlenecks
- Back end bottlenecks
- Fill rate
- Overdraw
- Occlusion Culling
- Shader optimization
- Consider using Shaders intended for mobile platforms
- Use small data types
- Avoid changing precision while swizzling
- Use GPU-optimized helper functions
- Disable unnecessary features
- Remove unnecessary input data
- Only expose necessary variables
- Reduce mathematical complexity
- Reduce texture lookups
- Avoid conditional statements
- Reduce data dependencies
- Surface Shaders
- Use Shader-based LOD
- Memory bandwidth
- VRAM limits
- Fill rate
- Lighting and Shadowing
- Optimizing graphics for mobile
- Summary
- 7. Masterful Memory Management
- 8. Tactical Tips and Tricks
- A. Bibliography
- Index
Variable scope is a fancy way of saying "Where in the script a variable exists." The following screenshot explains the scope of some variables:
You might have noticed that the rectangular blocks start and end with curly braces. Just like the AddTwoNumbers() method in Chapter 2, Introducing the Building Blocks for Unity Scripts, the code between an opening curly brace and a closing curly brace is called a code block. Absolutely wherever in a code you have an opening curly brace, there will be a closing curly brace to match. All of the code between the two braces is a code block. Notice that code blocks can be nested inside other code blocks.
Note
You normally won't create bare blocks of code with curly braces like I did in the case of Code Block 3. Code blocks usually include other things, such as if statements, looping statements, and methods. This example is just to demonstrate how the scope of a variable works and where a variable exists and is usable.
The following is what you have:
Line 16: string block3 = "Block 3 text";
The preceding line declares a local string variable named block3. This variable exists in the code block that is labeled Code Block 3. If you try to use the block3 variable outside of Code Block 3, such as in Code Block 2 or Code Block 1, Unity will give you an error message saying that the block3 variable doesn't exist.
The scope of the block3 variable is the code block defined by the curly braces of lines 13 and 18:
Line 6: string block1 = "Block 1 text";
The preceding line declares a string type member variable named block1. This variable exists in the code block that is labeled Code Block 1. This code block begins on line 5 and ends on line 20. This means that the block1 variable can be used everywhere, including Code Block 2 and Code Block 3, because they are also within Code Block 1. The block1 variable is used in Code Block 2 on line 10 and in Code Block 3 on line 14.
Thus, the scope of the block1 variable is the code block defined by the curly braces between lines 5 and 20.
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