1. Programming and Debugging
in Unity
Yingcai Xiao
Yingcai Xiao

2. Programming in Unity with C#

3. Scripting in Unity Unity supports: C# for heavy duty programing
JavaScripts for simple interactions
Boo: “compiled Python”, CLI, .NET, Mono compatible

4. C# Allow users to define events.
The de facto programming language for .NET
OS platform independent
Needs CLR (Common Language Runtime): .NET, Mono.
Unity uses Mono.
Supports: Class, Struct, Interface, Enum, Delegates
Allow users to define events.

5. C# Classes
Class: a group of code and data to be instantiated to form objects.
Four categories of class members:
Fields: member variables
Methods: member functions
Properties: fields exposed using accessor (get and set) methods
Events: notifications a class is capable of firing

6. Example: How to define a class in C#
class Rectangle {
// Fields
protected int width = 1;
protected int height = 1;
// Methods
public Rectangle () { }
public Rectangle (int cx, int cy)
width = cx;
height = cy; }

7. Example: How to define a class (user-defined data type)
// Accessor Methods
public void setWidth(int w) { width = w; }
public int getWidth() { return width; }
public void setHeight(int h) { height = h; }
public int getHeight() { return height; }
} // End of Rectangle class
// No “;” at the end of class definition.

8. Example: How to use a class in C#
Rectangle rect = new Rectangle(2,4);
rect.setHeight(8);
rect.setWidth(rect.getWidth() * 2);
double darea = (double) (rect.getWidth() * rect.getHeight() );
Note:
(1) “Rectangle rect” creats a reference, not object.
(2) Treat “Rectangle rect = new Rectangle();” in C#
as “Rectangle rect;” in C++.
(3) Use “rect.” to dereference in C#
instead of “rect->” as in C++.

9. Garbage Collection CLR controls garbage collection.
No need to free memory dynamically allocated with “new” on the heap in C#, hence, no destructors in C#.
CLR uses a reference counter to keep track the number of references pointing the memory.
CLR will free the memory when the reference counter becomes 0.
The Finalize() method (inherited from Object class) is called during garbage collection.
CLR decides when to perform garbage collection.
Force a garbage collection by calling GC.Collect (). (expensive)
Implement a Dispose method and call it when needed to cleanup when an object is not needed any more.

10. Example of Exception Handling
CLR’s Exception Handling Mechanism: try, catch, finally, and throw
File file = null; // Do not define it in the try block. Why?
try {
file = new File ("Readme.txt");
if(file != null) { /* Do the work here. */} … }
catch (FileNotFoundException e) { Console.WriteLine (e.Message); }
catch ( … ) { … }
finally { // Always come here even if there were exceptions.
if (file != null)
file.Close ();

11. C# vs. C++ C# C++ class myClass { } class myClass { } ;
Rectangle rect = new Rectangle();
Rectangle rect;
“rect.” to dereference
“rect->” to dereference
No destructors
~className();
Garbage Collection
free
using
#include
Single inheritance
Multiple inheritance

12. Differences between C++ & C#
Ending a block with a semicolon
Class myClass{ … }; }
Object instance creation
myClass myObject;
//myObject is an instance
myClass *myPointer
= new myClass();
//myPointer is a pointer to an instance
myClass myReference
//myReference is a reference (an internal pointer) to an instance
Dereferencing
myPointer->
myReference.
Class members
Fields: member variables
Methods: member functions
Properties: fields exposed using accessor (get and set) methods
Events: notifications a class is capable of firing
Freeing heap memory
free(myPointer);
Automatically by garbage collection when myReference is out of extent.

13. C# Books and Tutorials

14. Debugging in Unity3D (Contributed by Sai Goud Durgappagari)

15. Two ways of debugging: Print to a console window.
void SetCountText() {
count ++;
countText.text = “Count:” + count.ToString(); // to score board
print(“countText.text = ” + countText.text); // to console }
(2) Use the debugger in the IDE.
Unity3D uses debugger from Visual Studio.

16. Debugging in Unity
1. Debugging needs Visual Studio installed on your System. Visual Studio is available DreamSpark 2. After opening Unity 5 project and your script in Visual Studio, insert Breakpoints at respective lines of code to Debug 3. To insert Breakpoints, move your mouse to grey strip towards left side of editor and right click. Create as many Breakpoints needed and save the script.

20. Debugging in Unity
4. Debug->Debugging. If there is only one unity IDE is running, it will attach the process of the running unity IDE. Otherwise, it will ask you to select a process to attach if there are more than one unity programs are running. 5. Then go to Unity IDE and play the game. 6. The game pauses when it comes across one of your Breakpoints and Visual Studio gets highlighted.

26. Debugging in Unity
7. Go to Visual Studio and hover on variables to read their values. 8. Click on Continue to continue Debugging the game.