winless on Windows

winless_win32.c

#define NOMINMAX 1
#include <Windows.h>
#include <GL/gl.h>
#include <stdio.h>

#pragma comment (lib, "opengl32.lib")

typedef struct WindowData
{
	HDC dc;
	HGLRC rc;
} WindowData;

LRESULT CALLBACK WindowProcedure(HWND wnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
	switch (msg)
	{
		case WM_CREATE:
		{
			WindowData* wd = calloc(1, sizeof(WindowData));
			SetWindowLongPtr(wnd, GWLP_USERDATA, (LONG_PTR)(void*)wd);
			PIXELFORMATDESCRIPTOR pfd =
			{
				sizeof(PIXELFORMATDESCRIPTOR),
				1,
				PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,
				PFD_TYPE_RGBA,
				32,
				0, 0, 0, 0, 0, 0,
				0,
				0,
				0,
				0, 0, 0, 0,
				24,
				8,
				0,
				PFD_MAIN_PLANE,
				0,
				0, 0, 0
			};
			HDC dc = GetDC(wnd);
			wd->dc = dc;
			int pf = ChoosePixelFormat(dc, &pfd);
			SetPixelFormat(dc, pf, &pfd);

			wd->rc = wglCreateContext(dc);
			wglMakeCurrent(dc, wd->rc);

			char buf[2048];
			sprintf_s(buf, sizeof(buf), "OpenGL version %s\n", glGetString(GL_VERSION));
			OutputDebugStringA(buf);
			break;
		}
		case WM_DESTROY:
		{
			WindowData* wd = (WindowData*)(void*)GetWindowLongPtr(wnd, GWLP_USERDATA);
			wglMakeCurrent(wd->dc, NULL);
			wglDeleteContext(wd->rc);
			free(wd);
			PostQuitMessage(0);
			break;
		}
	}
	return DefWindowProc(wnd, msg, wparam, lparam);
}

HWND MakeWindow()
{
	WNDCLASSEX wc;
	ATOM classAtom;
	HMODULE mod;
	GetModuleHandleEx(
		GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
		GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
		(LPCWSTR)&WindowProcedure,
		&mod);
	memset(&wc, 0, sizeof(wc));
	wc.cbSize = sizeof(wc);
	wc.style = CS_OWNDC;
	wc.lpfnWndProc = &WindowProcedure;
	wc.hInstance = (HINSTANCE)mod;
	wc.lpszClassName = L"windowless-opengl";
	classAtom = RegisterClassEx(&wc);

	return CreateWindowEx(0, (LPCWSTR)classAtom, L"windowless-opengl",
		WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, 256, 256,
		NULL, NULL, (HINSTANCE)mod, NULL);
}

int WINAPI WinMain(HINSTANCE appInstance, HINSTANCE prevInstance, LPSTR commandLine, int showWindow)
{
	HWND wnd;
	wnd = MakeWindow();
	GLint tex;
	DestroyWindow(wnd);
	return 0;
}