/*
 * based on https://www.cs.rit.edu/~ncs/Courses/570/UserGuide/OpenGLonWin-11.html
 *
 * by Greg Couch, UCSF Computer Graphics Lab, 2016
 *
 * compile with:  cl stereotest-win.c
 */

#pragma warning(push, 1)
#include <windows.h>
#include <GL/gl.h>
#pragma warning(pop)

/* FULLSCREEN isn't work on GeForce even though stereo visuals are available */
#undef FULLSCREEN

#pragma comment (lib, "user32.lib")
#pragma comment (lib, "gdi32.lib")
#pragma comment (lib, "opengl32.lib")

static const char className[] = "OpenGL";
static const char windowName[] = "Stereo Test";

int winX = 0, winY = 0;
int winWidth = 200;
int winHeight = 200;


HDC hDC;
HGLRC hGLRC;

void
redraw(void)
{
	glDrawBuffer(GL_BACK_LEFT);
	glClearColor(1, 0, 0, 1);
	glClear(GL_COLOR_BUFFER_BIT);

	glDrawBuffer(GL_BACK_RIGHT);
	glClearColor(0, 0, 1, 1);
	glClear(GL_COLOR_BUFFER_BIT);

	SwapBuffers(hDC);
}

void
resize(void)
{
	/* set viewport to cover the window */
	glViewport(0, 0, winWidth, winHeight);
}

void
setupPixelFormat(void)
{
	PIXELFORMATDESCRIPTOR pfd = {
		sizeof(PIXELFORMATDESCRIPTOR),	/* size */
		1,				/* version */
		PFD_SUPPORT_OPENGL |
		PFD_DRAW_TO_WINDOW |
		PFD_DOUBLEBUFFER |		/* support double-buffering */
		PFD_STEREO,			/* want 3D stereo */
		PFD_TYPE_RGBA,			/* color type */
		24,				/* prefered color depth */
		0, 0, 0, 0, 0, 0,		/* color bits (ignored) */
		0,				/* no alpha buffer */
		0,				/* alpha bits (ignored) */
		0,				/* no accumulation buffer */
		0, 0, 0, 0,			/* accum bits (ignored) */
		0,				/* depth buffer */
		0,				/* no stencil buffer */
		0,				/* no auxiliary buffers */
		PFD_MAIN_PLANE,			/* main layer */
		0,				/* reserved */
		0, 0, 0,			/* no layer, visible, damage masks */
	};
	int pixelFormat;

	pixelFormat = ChoosePixelFormat(hDC, &pfd);
	if (pixelFormat == 0) {
		MessageBox(WindowFromDC(hDC), "ChoosePixelFormat failed.",
			"Error", MB_ICONERROR | MB_OK);
		exit(1);
	}


	if (SetPixelFormat(hDC, pixelFormat, &pfd) != TRUE) {
		MessageBox(WindowFromDC(hDC), "SetPixelFormat failed.",
			"Error", MB_ICONERROR | MB_OK);
		exit(1);
	}

	/* confirm that we get a stereo pixel format */
	DescribePixelFormat(hDC, pixelFormat, sizeof (pfd), &pfd);
	if ((pfd.dwFlags & PFD_STEREO) == 0) {
		MessageBox(WindowFromDC(hDC), "Unable to get stereo pixel format.",
			"Error", MB_ICONERROR | MB_OK);
		exit(1);
	}
}

LRESULT APIENTRY
WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message) {

		case WM_CREATE:
			/* initialize OpenGL rendering */
			hDC = GetDC(hWnd);
			setupPixelFormat();
			hGLRC = wglCreateContext(hDC);
			wglMakeCurrent(hDC, hGLRC);
			return 0;

		case WM_DESTROY:
			/* finish OpenGL rendering */
			if (hGLRC) {
				wglMakeCurrent(NULL, NULL);
				wglDeleteContext(hGLRC);
			}
			ReleaseDC(hWnd, hDC);
			PostQuitMessage(0);
			return 0;

		case WM_SIZE:
			/* track window size changes */
			if (hGLRC) {
				winWidth = (int) LOWORD(lParam);
				winHeight = (int) HIWORD(lParam);
				resize();
				return 0;
			}

		case WM_PAINT:
			{
				PAINTSTRUCT ps;
				BeginPaint(hWnd, &ps);
				if (hGLRC) {
					redraw();
				}
				EndPaint(hWnd, &ps);
				return 0;
			}
			break;

		case WM_LBUTTONDOWN:
		case WM_CHAR:
			DestroyWindow(hWnd);
			return 0;

		default:
			break;
	}
	return DefWindowProc(hWnd, message, wParam, lParam);
}


int APIENTRY
WinMain(__in HINSTANCE hCurrentInst, __in_opt HINSTANCE hPreviousInst,
	__in_opt LPSTR lpszCmdLine, __in_opt int nCmdShow)
{
	WNDCLASS wndClass;
	HWND hWnd;
	MSG msg;
#ifdef FULLSCREEN
	HMONITOR hmon;
	MONITORINFO mi;

	mi.cbSize = sizeof mi;
	hmon = MonitorFromWindow(GetDesktopWindow(), MONITOR_DEFAULTTONEAREST);
	if (hmon && GetMonitorInfo(hmon, &mi)) {
		winX = mi.rcMonitor.left;
		winY = mi.rcMonitor.top;
		winWidth = mi.rcMonitor.right - mi.rcMonitor.left; 
		winHeight = mi.rcMonitor.bottom - mi.rcMonitor.top; 
	}
#endif

	/* register window class */
	wndClass.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
	wndClass.lpfnWndProc = WndProc;
	wndClass.cbClsExtra = 0;
	wndClass.cbWndExtra = 0;
	wndClass.hInstance = hCurrentInst;
	wndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wndClass.hCursor = LoadCursor(NULL, IDC_ARROW);
	wndClass.hbrBackground = GetStockObject(BLACK_BRUSH);
	wndClass.lpszMenuName = NULL;
	wndClass.lpszClassName = className;
	RegisterClass(&wndClass);

	/* create window */
	hWnd = CreateWindowEx(
		WS_EX_APPWINDOW | WS_EX_TOPMOST,
		className, windowName,
#ifdef FULLSCREEN
		WS_POPUP
#else
		WS_OVERLAPPEDWINDOW
#endif
		| WS_VISIBLE | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
		winX, winY, winWidth, winHeight,
		NULL, NULL, hCurrentInst, NULL);

	/* display window */
#ifdef FULLSCREEN
	ShowWindow(hWnd, SW_MAXIMIZE);
#else
	ShowWindow(hWnd, nCmdShow);
#endif
	UpdateWindow(hWnd);

	/* process messages */
	while (GetMessage(&msg, NULL, 0, 0) == TRUE) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return (int) msg.wParam;
}