Location and hours. Game Programming in C++ About this course. This course is about. About this course. About this course

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1 Location and hours Game Programming in C++ Arjan Egges Lecture #1: Introduction, C++ basics Lectures Arjan Egges ( Room: BBL 065 Every Monday 1pm-3pm and Thursday 9am-11am Practical assignments Ben van Basten ( Rooms BBL-017, BBL-103, BBL-106, BBL115 Every Monday 3pm-5pm and Thursday 11am-1pm Please regularly consult website for updates: This course is about Cool Graphics Real-time Rendering, Shading Character Animation Artificial Intelligence Real-time Physics Designing Games and Levels About this course Introduction to the C++ programming language C++ has some distinct differences from Java/C# C++ is widely used in the industry Programming techniques for game development Games are very difficult applications to build Many different complex interactions with the program are required Uses many different hardware components Uses many resources (audio, visual, other data) About this course Game engines Concepts used, architecture How to properly use a game engine There are many C++ books, and many Game Programming books, but only a few books that properly handle both Book we use in this course: C++ for Game Programmers: Second Edition by Michael J. Dickheiser. Charles River Media, ISBN About this course Other interesting links: - Games and Game Programming website - Java to C++ tutorial Game/graphics engines: OGRE Delta3D Irrlicht And more 1

2 Practical assignments In the lectures, we will discuss programming techniques in C++ and game engine architecture There are several practical assignments that address topics discussed in the lecture Visual C++ tutorial during the first assignment In total 5 practical assignments Assignments will be done in teams of 2 Assignments 2-5 need to be approved to finish the course Practical assignments First three assignments: focused on using different C++ features. Last two assignments will be done with OGRE3D OGRE3D is a well-known graphics engine based on DirectX/OpenGL Not really a game engine, but a graphics engine Lecture schedule First four lectures will be overview of C++ C++ basics (variables, classes, functions ) Memory management (pointers, creating and deleting objects) Object-oriented programming in C++ The remainder of the lectures will address various chapters in the book Next to the material discussed in the book we will also look into existing game engine architectures (OGRE, Delta3D, Unreal, ) Hands-on programming exercises C++ versus other languages C++ vs. Java Java is interpreted Java is 100% object oriented (no global variables, etc.) C++ has separate class declaration and definition Strings are handled better in Java All non-primitive objects in Java are created using new Java class has no destructors C++ versus other languages C++ vs. C# C# doesn t allow for multiple inheritance, C++ does C# is higher level (less control over memory management, object lifetime, and so on) C# doesn t support templates C# has the extensive.net framework with lots of useful components, such as GUI, cryptography, networking, etc. In C# everything derives from a generic Object class (like in Java) Which language to use? So why not Game Programming in Java or Game Programming in C#? C++ is still an industry standard Many games are programmed in C++ or use (older) libraries written in C++ In games, object lifetime management is sometimes still necessary Understanding these concepts is very useful 2

3 Which language to use? Mostly, game companies use C++ for building their games C++ allows for both high- and low-level coding A lot of libraries and code is available Precise control over object lifetime, memory management, etc. Java is rarely used for games, but a lot of development is going on for Java3D, jmonkey engine, Java Scene Graphs, etc. C# is used in combination with XNA to produce Xbox games C# also neatly integrates with existing C++ libraries More game companies start to use C# for their games In Java: public class HelloWorld { /* Declare the main function. */ public static void main(string args[]) { System.out.println("Hello world!"); In C: // the printf function is located here #include <stdio.h> int main(int argc, char* argv[]) { printf("hello world!\n"); return 0; A few differences: C has global functions and no classes The printf function is loaded from a library In Java, the main takes one parameter as opposed to 2 in C In Java, the main does not return an exit code In C++: // cout is located here A simpler version also works: // cout is located here int main(int argc, char* argv[]) { cout << "Hello world!" << endl; return 0; void main() { cout << "Hello world!" << endl; 3

4 Hello, world The #include statement loads the iostream library used for printing and reading data from the keyboard Similar to packages in Java, C++ uses namespaces The using namespace std simply means that we will use functions/objects from the namespace std. Types in C++ Like Java/C#, C++ has primitive types like int, float, double C++ has no String class Use array of char or STL string (next lecture) No built in null keyword, but C++ uses 0 In many libraries, NULL is defined as macro for 0 to increase readability Definition: Usage: Enumerated types enum AvatarType { Wizard, Soldier, Spy, Blacksmith ; AvatarType myavatar = Soldier; AvatarType youravatar = Wizard; int r = fighttothedeath(myavatar, youravatar); Expressions Numeric expressions can cause many bugs if not taken care Implicit casting in C++ does not generate compiler error like in Java: int x = 5; int y = 2; double z = 5.0; double a = x / y; // a equals 2 double b = z / y; // b equals 2.5 double c = double(x)/double(y); // c equals 2.5 Expressions Booleans C++ knows a primitive bool type Creating and using boolean variables: bool x = true; bool y = false; 0 = false Non-zero (but normally 1) = true Standard logical operators are available (<=,!=, &&, ) Expressions!x Returns false if x is true and vice-versa. x < y Returns true if x is less than y. x > y Returns true if x is greater than y. x <= y Returns true if x is less than or equal to y. x >= y Returns true if x is greater than or equal to y. x == y Returns true if x and y are equal. x!= y Returns true if x and y are not equal. x && y Returns true only if both x and y are true. x ^^ y Returns true if either x or y is true (not both). x y Returns true if one of x or y is true (or both). 4

5 Expressions Always use parentheses in complex boolean expressions Easy to forget precedence rules Easier to read/understand for others Please note the difference between = and == Wrong use in Java creates a compile-time error, but not in C++! If-statement: For-loop: Conditional/Iteration if (c!= 'y' && c!= 'n') { cout << "Please choose yes or no: " << endl; cin >> c; // Input from user else for (int i = 0; i < 10; i++) cout << "The next number is:" << i << endl; Conditional statement Switch statement Example: switch (option) { case 'a': cout << "You chose option A" << endl; break; case 'b': cout << "You chose option B" << endl; break; default: cout << "Invalid option!" << endl; Conditional statement Combining cases: switch (option) { case 'a': case 'b': case 'c': cout << "Normal menu option" << endl; break; case '?': cout << "Help option" << endl; break; default: cout << "Invalid option!" << endl; An example application Write a C++ program that outputs the following pattern of asterisks: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * An example application void main() { cout << "*" << endl; cout << "* *" << endl; cout << "* * *" << endl; cout << "* * * *" << endl; cout << "* * * * *" << endl; cout << "* * * * * *" << endl; cout << "* * * * * * *" << endl; cout << "* * * * * * * *" << endl; 5

6 An example application void main() { cout << "Please enter the tree size: "; int treesize; cin >> treesize; cout << endl; for (int i=1; i<treesize; i++) { for (int j=0; j<i; j++) cout << "* "; cout << endl; While loop: Do-while loop: Iteration int a = 20; while ((a * 2) < 100) { a += 5; cout << a << endl; int a = 20; do a += 10; while ((a / 10) <= 4); An example application // Countdown program void main () { int n; cout << Enter the starting number: ; cin >> n; while (n > 0) { cout << n << ", "; n--; cout << "FIRE!" << endl; Input/Output Using the C++ iostream library Necessary include: Printing output on the screen: cout << "Hello, world!" << endl; cout << "The nr of points: " << points << endl; Receiving input from keyboard: int a = 0; cout << "Please enter a number: "; cin >> a; Input/Output This version guarantees no namespace conflict: Cout usage with namespace: std::cout << "Hello, world" << std::endl; Similar for cin and other objects/functions in the namespace // Writing a text file #include <fstream> File IO void main () { ofstream myfile("example.txt"); if (myfile.is_open()) { myfile << "This is a line." << endl; myfile << "And another line." << endl; myfile.close(); else cout << "Unable to open file"; 6

7 // Reading a text file #include <fstream> #include <string> void main() { string line; ifstream myfile("example.txt"); if (myfile.is_open()) { while (!myfile.eof() ) { getline(myfile,line); cout << line << endl; myfile.close(); else cout << "Unable to open file"; Variable types in C/C++ Normal variable: int a; Reference: double w = 3.4; double& b = w; Pointers (more about that later) Scope Variables are only accessible in the block in which they were defined if (x == 12) { double z = 48.7; cout << z << endl; for (int i = 0; i < 10; i++) { cout << i << endl; cout << i << endl; Functions Structure programs in a modular way Syntax: type name ( parameter1, parameter2,...) { statement Type: data type specifier Name: function identifier Parameters: each consists of data type specifier + parameter name Statement: the function body Functions int addition(int a, int b) { int r; r = a + b; return r; int main() { int z; z = addition(5,3); cout << "The result is " << z << endl; return 0; Functions A function with no parameters and no return type: void printmessage(void) { cout << "I'm a function!" << endl; Or: void printmessage() { cout << "I'm a function!" << endl; 7

8 Functions Functions Passing arguments by reference: void duplicate(int& a, int& b, int& c) { a*=2; b*=2; c*=2; int main() { int x=1; int y=3; int z=7; duplicate(x, y, z); cout << "x=" << x << ", y=" << y; cout << ", z=" << z << endl; return 0; void odd(int a); void even(int a); Declaring functions void main () { int i; do { cout << "Type a number (0 to exit): "; cin >> i; odd(i); while (i!=0); Declaring functions void odd(int a) { if ((a%2)!= 0) cout << "Number is odd." << endl; else even(a); void even(int a) { if ((a%2) == 0) cout << "Number is even." << endl; else odd(a); Building an executable Multiple steps: Preprocessor Evaluate macros and includes Compiler Create object files (.obj) from C++ code Linker Resolve the links between different parts of code, for example include libraries, MFC, etc. Create executable #include statements Preprocessor // standard IO library #include <cmath> // math functions #include "myownheader.h" // own header file < > look in standard directories look in working directory as well as standard directory Try to include as few headers as possible 8

9 Preprocessor #define statement Tells the preprocessor to do a text replace in the code #define PI 3.14 Can be useful for generic constants used everywhere in your program A macro can be undefined using the #undef statement Preprocessor You can use the preprocessor to conditionally compile code: #define CUSTOMXML #ifdef CUSTOMXML #include <mycustomxmlparser/saxparser.h> #include <mycustomxmlparser/saxhandle.h> #endif #ifndef CUSTOMXML #include <xmlparser2.1/saxparser.h> #include <xmlparser2.1/saxhandle.h> #endif Summary Basic overview of C++ syntax and usage Constructs Functions Expressions How to compile a C++ application Next lecture: Pointers and memory management Arrays 9