Windows API OpenGL initialization

windows_c_opengl.c

#include <stdio.h>

#include <windows.h>
#include <gl/GL.h>

HDC dc;
HGLRC rc;

LRESULT CALLBACK WindowProc(HWND hwnd,
    UINT msg,
    WPARAM wParam,
    LPARAM lParam)
{
    switch (msg)
    {
    case WM_CREATE:
    {
        PIXELFORMATDESCRIPTOR pfd = {
            sizeof(PIXELFORMATDESCRIPTOR),  //  size of this pfd  
            1,                     // version number  
            PFD_DRAW_TO_WINDOW |   // support window  
                PFD_SUPPORT_OPENGL |   // support OpenGL  
                PFD_DOUBLEBUFFER,      // double buffered  
            PFD_TYPE_RGBA,         // RGBA type  
            24,                    // 24-bit color depth  
            0, 0, 0, 0, 0, 0,      // color bits ignored  
            0,                     // no alpha buffer  
            0,                     // shift bit ignored  
            0,                     // no accumulation buffer  
            0, 0, 0, 0,            // accum bits ignored  
            32,                    // 32-bit z-buffer      
            0,                     // no stencil buffer  
            0,                     // no auxiliary buffer  
            PFD_MAIN_PLANE,        // main layer  
            0,                     // reserved  
            0, 0, 0                // layer masks ignored  
        };
        dc = GetDC(hwnd);
        int pf = ChoosePixelFormat(dc, &pfd);
        SetPixelFormat(dc, pf, &pfd);
        rc = wglCreateContext(dc);
        wglMakeCurrent(dc, rc);
        glViewport(0, 0, 640, 480);
        //MessageBoxA(0, glGetString(GL_VERSION), "OPENGL VERSION", 0);
        return 0;
    } break;
    
    // WM_CLOSE
    case WM_CLOSE:
    {
        if(MessageBox(hwnd, L"Quit?", L"App", MB_OKCANCEL) == IDOK)
        {
            DestroyWindow(hwnd);
        }
        return 0;
    } break;
    
    case WM_DESTROY:
    {
        ReleaseDC(hwnd, dc);
        wglDeleteContext(rc);
        PostQuitMessage(0);
        return 0;
    } break;

    default:
    {
        return DefWindowProc(hwnd, msg, wParam, lParam);
    } break;
    }
    return 0;
}

int main()
{
	WNDCLASS wc = { 0 };

	const wchar_t CLASS_NAME[] = L"Tutorial";
	wc.lpszClassName = CLASS_NAME;
	wc.lpfnWndProc = WindowProc;
	wc.hInstance = GetModuleHandle(NULL);

	RegisterClass(&wc);

	// create window

	HWND hwnd;
    
	int width = 640;
	int height = 480;
	RECT wr = { 0, 0, width, height };
	AdjustWindowRect(&wr, WS_OVERLAPPEDWINDOW, FALSE);

	hwnd = CreateWindow(CLASS_NAME, CLASS_NAME,
		WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		0, 0,
		wr.right - wr.left,
		wr.bottom - wr.top,
		0, 0, wc.hInstance, 0);

	if (hwnd == NULL)
	{
		return 1;
	}

	ShowWindow(hwnd, SW_SHOW);

	// game loop

	MSG msg = { 0 };

	int running = 1;

	while (running)
	{
		while (PeekMessage(&msg, 0, 0, 0, PM_REMOVE))
		{
			if (msg.message == WM_QUIT)
			{
				running = 0;
			}

			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}

		// update, render
		glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
		SwapBuffers(dc);
	}

	return 0;
}