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Welcome to the first tutorial !
Before jumping into OpenGL, you will first learn how to build the code that goes with each tutorial, how to run it, and most importantly, how to play with the code yourself.
No special prerequisite is needed to follow these tutorials. Experience with any programming langage ( C, Java, Lisp, Javascript, whatever ) is better to fully understand the code, but not needed ; it will merely be more complicated to learn two things at the same time.
All tutorials are written in “Easy C++” : Lots of effort has been made to make the code as simple as possible. No templates, no classes, no pointers. This way, you will be able to understand everything even if you only know Java.
You don’t have to know anything, but you have to forget everything you know about OpenGL.
If you know about something that looks like glBegin(), forget it. Here you will learn modern OpenGL (OpenGL 3 and 4) , and most online tutorials teach “old” OpenGL (OpenGL 1 and 2). So forget everything you might know before your brain melts from the mix.
All tutorials can be built on Windows, Linux and Mac. For all these platforms, the procedure is roughly the same :
Detailed procedures will now be given for each platform. Adaptations may be required. If unsure, read the instruction for Windows and try to adapt them.
You can also launch any tutorial from inside Visual Studio. Right-click on Playground once, “Choose as startup project”. You can now debug the code by pressing F5.
They are so many Linux variants out there that it’s impossible to list every possible platform. Adapt if required, and don’t hesitate to read your distribution’s documentation.
Note that you really should use an IDE like Qt Creator. In particular, this one has built-in support for CMake, and it will provide a much nicer experience when debugging. Here are the instructions for QtCreator :
Mac OS doesn’t support OpenGL 3.3. Recent Macs with MacOS 10.7 Lion and compatible GPUs can run OpenGL 3.2, but not 3.3. Use the 2.1 port of the tutorials instead. Apart from that, the procedure is very similar to Windows’ (Makefiles are also supported, but won’t be explained here) :
Due to 2 bugs (one in C::B, one in CMake), you have to edit the command-line in Project->Build Options->Make commands, as follows :
You also have to setup the working directory yourself : Project->Properties -> Build targets -> tutorial N -> execution working dir ( it’s src_dir/tutorial_N/ ).
You should run the tutorials directly from the right directory : simply double-click on the executable. If you like command line best, cd to the right directory.
If you want to run the tutorials from the IDE, don’t forget to read the instructions above to set the correct working directory.
Each tutorial comes with its source code and data, which can be found in tutorialXX/. However, you will never modify these projects : they are for reference only. Open playground/playground.cpp, and tweak this file instead. Torture it in any way you like. If you are lost, simply cut’n paste any tutorial in it, and everything should be back to normal.
We will provide snippets of code all along the tutorials. Don’t hesitate to cut’n paste them directly in the playground while you’re reading : experimentation is good. Avoid simply reading the finished code, you won’t learn a lot this way. Even with simple cut’n pasting, you’ll get your boatload of problems.
Finally ! OpenGL code !
Well, not really. All tutorials show you the “low level” way to do things, so that you can see that no magic happens. But this part is actually very boring and useless, so we will use GLFW, an external library, to do this for us instead. If you really wanted to, you could use the Win32 API on Windows, the X11 API on Linux, and the Cocoa API on Mac; or use another library like SFML, FreeGLUT, SDL, … see the Links page.
Ok, let’s go. First, we’ll have to deal with dependencies : we need some basic stuff to display messages in the console :
First, GLEW. So this one actually is a little bit magic, but let’s leave this for later.
We decided to let GLFW handle the window and the keyboard, so let’s include it too :
We don’t actually need this one right now, but this is a library for 3D mathematics. It will prove very useful soon. There is no magic in GLM, you can write your own if you want; it’s just handy. The “using namespace” is there to avoid typing “glm::vec3″, but “vec3″ instead.
If you cut’n paste all these #include’s in playground.cpp, the compiler will complain that there is no main() function. So let’s create one :
First thing to do it to initialize GLFW :
We can now create our first OpenGL window !
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // We want OpenGL 3.3 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // To make MacOS happy; should not be needed glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //We don't want the old OpenGL // Open a window and create its OpenGL context GLFWwindow* window; // (In the accompanying source code, this variable is global) window = glfwCreateWindow( 1024, 768, "Tutorial 01" , NULL, NULL); if ( window == NULL ){ fprintf ( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" ); glfwTerminate(); return -1; } glfwMakeContextCurrent(window); // Initialize GLEW glewExperimental= true ; // Needed in core profile if (glewInit() != GLEW_OK) { fprintf (stderr, "Failed to initialize GLEW\n" ); return -1; } |
Build this and run. A window should appear, and be closed right away. Of course ! We need to wait until the user hits the Escape key :
1 2 3 4 5 6 7 8 9 10 11 12 13 | // Ensure we can capture the escape key being pressed below glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE); do { // Draw nothing, see you in tutorial 2 ! // Swap buffers glfwSwapBuffers(window); glfwPollEvents(); } // Check if the ESC key was pressed or the window was closed while ( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS && glfwWindowShouldClose(window) == 0 ); |
And this concludes our first tutorial ! In Tutorial 2, you will learn how to actually draw a triangle.
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