#include <windows.h>
#include <gl/gl.h>
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
void EnableOpenGL(HWND hWnd, HDC * hDC, HGLRC * hRC);
void DisableOpenGL(HWND hWnd, HDC hDC, HGLRC hRC);
void render(void);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow);
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
void EnableOpenGL(HWND hWnd, HDC * hDC, HGLRC * hRC);
void DisableOpenGL(HWND hWnd, HDC hDC, HGLRC hRC);
extern float theta;
float theta = 0.0f;
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
void EnableOpenGL(HWND hWnd, HDC * hDC, HGLRC * hRC);
void DisableOpenGL(HWND hWnd, HDC hDC, HGLRC hRC);
void render(void)
{
	glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
	glClear( GL_COLOR_BUFFER_BIT );
	
	glPushMatrix();
	glRotatef( theta, 0.0f, 0.0f, 1.0f );
	glBegin( GL_TRIANGLES );
	glColor3f( 1.0f, 0.0f, 0.0f ); glVertex2f( 0.0f, 1.0f );
	glColor3f( 0.0f, 1.0f, 0.0f ); glVertex2f( 0.87f, -0.5f );
	glColor3f( 0.0f, 0.0f, 1.0f ); glVertex2f( -0.87f, -0.5f );
	glEnd();
	glPopMatrix();
	
	theta += 1.0f;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow)
{
	WNDCLASS wc;
	HWND hWnd;
	HDC hDC;
	HGLRC hRC;
	MSG msg;
	BOOL quit = FALSE;
	
	wc.style = CS_OWNDC;
	wc.lpfnWndProc = WndProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance;
	wc.hIcon = LoadIcon( NULL, IDI_APPLICATION );
	wc.hCursor = LoadCursor( NULL, IDC_ARROW );
	wc.hbrBackground = (HBRUSH)GetStockObject( BLACK_BRUSH );
	wc.lpszMenuName = NULL;
	wc.lpszClassName = "geon";
	RegisterClass( &wc );
	
	hWnd = CreateWindow( "geon", "geon", WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE, 0, 0, 256, 256, NULL, NULL, hInstance, NULL );
	
	EnableOpenGL( hWnd, &hDC, &hRC );
	
	while(!quit)
	{
		if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ))
		{
			if(( msg.message == WM_QUIT ))
			{
				quit = TRUE;
			}
			else
			{
				TranslateMessage( &msg );
				DispatchMessage( &msg );
			}
		}
		else
		{
			render();
			SwapBuffers( hDC );
		}
	}
	
	DisableOpenGL( hWnd, hDC, hRC );
	
	DestroyWindow( hWnd );
	
	return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	// brace's swtich / case syntax is pretty crap, ins't it?  :)
	switch(message)
	{
	case WM_CREATE:	return 0;
	case WM_CLOSE:	PostQuitMessage( 0 );
		return 0;
	case WM_DESTROY:	return 0;
	case WM_KEYDOWN:	switch( wParam)
		{
		case VK_ESCAPE:	PostQuitMessage(0);
			return 0;
		}
		return 0;
	default:	return DefWindowProc( hWnd, message, wParam, lParam );
	}
}
void EnableOpenGL(HWND hWnd, HDC * hDC, HGLRC * hRC)
{
	PIXELFORMATDESCRIPTOR pfd;
	int format;
	
	*hDC = GetDC( hWnd );
	
	// set the pixel format for the DC
	ZeroMemory( &pfd, sizeof( pfd ) );
	pfd.nSize = sizeof( pfd );
	pfd.nVersion = 1;
	pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
	pfd.iPixelType = PFD_TYPE_RGBA;
	pfd.cColorBits = 24;
	pfd.cDepthBits = 16;
	pfd.iLayerType = PFD_MAIN_PLANE;
	format = ChoosePixelFormat( *hDC, &pfd );
	SetPixelFormat( *hDC, format, &pfd );
	
	*hRC = wglCreateContext( *hDC );
	wglMakeCurrent( *hDC, *hRC );
}
void DisableOpenGL(HWND hWnd, HDC hDC, HGLRC hRC)
{
	wglMakeCurrent( NULL, NULL );
	wglDeleteContext( hRC );
	ReleaseDC( hWnd, hDC );
}