/opengl-adventures

Primary LanguageC++

Exploring the Process of Learning Game Development with C++ and OpenGL: An Adventure in Skill Acquisition

This is a work in progress and I'm learning as I go while documenting my progress. I want to use VS Code as my IDE so I know there might be some challenges.

I'm not an expert in C++ or OpenGL but I have a really basic understanding of both. My professional background is in web development using React and Node.js. I also have some experience with Godot Game Engine.

I'll be using this YouTube playlist by The Cherno as a guide and a LOT of ChatGPT to help me figure things out. I'll be using Visual Studio Code as my IDE and MinGW as my compiler.

Environment Setup

I have already installed VS Code and Chocolatey. I'm using Windows 10 just in case.

The first thing I did was install the following C/C++ Extension Pack extension for VS Code.

Then I installed MinGW using Chocolatey.

choco install mingw

To verify that MinGW was installed correctly, I ran the following command.

g++ --version

Compiling and Running

To compile and run the program, I ran the following command.

g++ hello.cpp -o hello.exe && ./hello.exe

GLFW

I'm using GLFW to create a window and handle input. I downloaded the pre-compiled binaries for Windows and extracted the include and lib-mingw-w64 folders to a folder called dependencies/glfw-3.3.8.WIN64 in the root of the project.

Next, I created a c_cpp_properties.json file in the .vscode folder so VS Code is able find the GLFW header files.

Finally, I had to setup the library path. This took A LOT of time (3 hours?). These are my findings:

  • Even though I was trying to build a 32-bit application, I had to use the 64-bit GLFW library files. I'm not sure why. Maybe it's because I'm using a 64-bit version of MinGW/Windows?
  • I had issues debugging the build command. I had much better results when I discovered and created the tasks.json file. Important finding: THE task.json file must be in the .vscode folder. I had it in the root of the project and it was getting ignored.
  • I was able to open the build output window by pressing Ctrl+Shift+B adding a new task that runs by default.

After all that, I was able to compile and run the program with CTRL+SHIFT+B and VOILA! A window appeared with a black background. ⬛🪟🥳

GLEW

I'm using GLEW to load OpenGL functions. I downloaded the pre-compiled binaries for Windows and extracted the include and lib-x64 folders to a folder called dependencies/glew-2.1.0 in the root of the project.

Then I followed the same steps as I did for GLFW to setup the library path. The two main issues I had were:

  • I had to set the GLEW_STATIC preprocessor definition. I had some issues with this because I was setting it in the c_cpp_properties.json file but it wasn't working. I had to set it in the tasks.json file.
  • When adding the glew32s library, I had to add if before the opengl32 library. I'm not sure why but this is what worked for me.

Modern OpenGL and Shaders

This was very straightforward. I just followed the instructions in the video and it worked. The only thing I had to do was change the #version 330 core to #version 410 in the vertex and fragment shaders. In the video this worked but I was getting an error. Changing the version or adding #extension GL_ARB_explicit_uniform_location : enable to the top of the shaders fixed the issue. The version seemed to be the better solution for me.

After this step I had a shader parser that was able to load and compile shaders. And most important: I had a red triangle on the screen! 🔺🔺🔺

The Mighty Square and Index Buffers

Drawing a square was easy: Just draw two triangles! But there's a better way to do this: Index Buffers. I followed the instructions to define a list of vertices and a list of indices. After some minor changes to the code, I had a square on the screen! 🟦

Vertex Buffers

After setting the profile to 'core', OpenGL no longer creates a default vertex array object under the hood. This took a bit to understand so I left a lot of comments in the code. The idea is that the vertex array object is a container for vertex buffers and vertex attributes. Now I don't have to bind the vertex array object every time I want to draw something. I just bind it once and then bind the vertex buffer and vertex attributes. This is supposed to be a lot cleaner and easier to understand later on when I have more complex objects and scenes.

Abstractions

The code is starting to get a bit messy. The tutorial suggests abstracting the Vertex Array, Vertex Buffer, Index Buffer and Shader into classes. No major issues with this except that I had to change one cast in the VertexArray class from (const void*)offset to (const void*)(uintptr_t)offset. The compiler was showing a warning and chatgpt suggested this solution. I'm not sure why it worked but it did. Something about the size of an int and a pointer being different.