Followed guides for GLFW:

• GLFW Getting Started guide
• GLFW Building applications guide

I'm following the OpenGL Course from freecodecamp.

In the middle I got a bit confused about all the buffers (VAOs, VBOs, etc.) so to better understand what buffers are in OpenGL, I watched From CPU to GPU: Understanding Data Transfer with Buffers in OpenGL.

Then I went on a bit of watching spree.

• I really enjoyed this Minecraft Clone series

• Video that explains how the graphics pipeline works

[!NOTE]

There's quite a good official wiki on OpenGL: https://www.khronos.org/opengl/wiki/Main_Page.

First, I have to ask OpenGL for a buffer:

int size = 1;
int bufferName; // this variable could be called VBO (Vertex Buffer Object)
glGenBuffers(size, &bufferName);

Then bufferName may be e.g., 124 (yes, this number is a name).

We now have a buffer name but it's empty.

Then the buffer has to be binded ("made bound") to specific target using glBindBuffer. The target specifies how you intend to use the buffer (e.g., for vertex attributes, indices, etc.).

glBindBuffer(GL_ARRAY_BUFFER, bufferName);

This tells OpenGL that the bufferName should now be used as the current buffer for the GL_ARRAY_BUFFER target. The GL_ARRAY_BUFFER target is typically used for vertex attribute data.

Finally, I can put data into the buffer (this is the "from CPU to GPU" move of data) with glBufferData.

// A simple triangle
GLfloat vertices[] = {
    0.5f, 0.5f, 0,
    1.5f, 0.5f, 0,
    1.0f, 1.5f, 0,
    };
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

GL_ARRAY_BUFFER stores vertices.

GL_ELEMENT_ARRAY_BUFFER stores indices.