Win32 opengl Window creation - winapi

Question

What is the best way to set up a window in win32 that has OpenGl(and glsl if the needs extra code to work) integrated into it?
I have done some research and found numerous ways of accomplishing this task i was wondering what the best way is or what way you like the most if the best way doesn't have an answer.
I have looked at nehe`s design and also the one supplied by the OpenGl super bible which both have completely different ways of accomplishing it (also the super bibles one gives me errors :().
any help would be appreciated including tutorials etc.
thanks

Answer 1

All your "different ways" aren't so different. You have to:
create your window (in the usual Win32 way, with RegisterClass(Ex) and CreateWindow(Ex))
create a GDI device context corresponding to your window (GetDC)
pick a pixel format which is supported by the display (optional DescribePixelFormat, then ChoosePixelFormat)
create your OpenGL context (wglCreateContext)
(optional, but required to use GLSL) link OpenGL extension functions (GLee or GLEW helpers, or glGetString(GL_EXTENSIONS) then wglGetProcAddress)
(optional) create an OpenGL 3.x context, free the compatibility context (wglCreateContextAttribs)
make the context active (wglMakeCurrent)
start using OpenGL (set up shader programs, load textures, draw stuff, etc.)
An excerpt of code showing these steps in action (not suitable for copy+paste, a bunch of RAII wrappers are used):
bool Context::attach( HWND hwnd )
{
PIXELFORMATDESCRIPTOR pfd = { sizeof(pfd), 1 };
if (!m_dc) {
scoped_window_hdc(hwnd).swap(m_dc);
pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_SUPPORT_COMPOSITION | PFD_DOUBLEBUFFER;
pfd.iPixelType = PFD_TYPE_RGBA;
pfd.cColorBits = 32;
pfd.cAlphaBits = 8;
pfd.iLayerType = PFD_MAIN_PLANE;
auto format_index = ::ChoosePixelFormat(m_dc.get(), &pfd);
if (!format_index)
return false;
if (!::SetPixelFormat(m_dc.get(), format_index, &pfd))
return false;
}
auto active_format_index = ::GetPixelFormat(m_dc.get());
if (!active_format_index)
return false;
if (!::DescribePixelFormat(m_dc.get(), active_format_index, sizeof pfd, &pfd))
return false;
if ((pfd.dwFlags & PFD_SUPPORT_OPENGL) != PFD_SUPPORT_OPENGL)
return false;
m_render_thread = ::CreateThread(NULL, 0, &RenderThreadProc, this, 0, NULL);
return m_render_thread != NULL;
}
DWORD WINAPI Context::RenderThreadProc( LPVOID param )
{
Context* const ctx = static_cast<Context*>(param);
HDC dc = ctx->m_dc.get();
SIZE canvas_size;
ctx->m_dc.check_resize(&canvas_size);
scoped_hglrc glrc(wglCreateContext(dc));
if (!glrc)
return EXIT_FAILURE;
if (!glrc.make_current(dc))
return EXIT_FAILURE;
if (ctx->m_major_version > 2 && GLEE_WGL_ARB_create_context) {
int const create_attribs[] = {
WGL_CONTEXT_MAJOR_VERSION_ARB, ctx->m_major_version,
WGL_CONTEXT_MINOR_VERSION_ARB, ctx->m_minor_version,
0
};
scoped_hglrc advrc(wglCreateContextAttribsARB(dc, 0, create_attribs));
if (advrc) {
if (!advrc.make_current(dc))
return EXIT_FAILURE;
advrc.swap(glrc);
}
}
{
const char* ver = reinterpret_cast<const char*>(glGetString(GL_VERSION));
if (ver) {
OutputDebugStringA("GL_VERSION = \"");
OutputDebugStringA(ver);
OutputDebugStringA("\"\n");
}
}
glDisable(GL_DITHER);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0.f, 0.f, 0.f, 1.f);
if (GLEE_WGL_EXT_swap_control)
wglSwapIntervalEXT(1);
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
while (!::InterlockedExchange(&ctx->m_stop_render, 0)) {
ctx->process_queued_tasks();
if (ctx->m_dc.check_resize(&canvas_size)) {
glViewport(0, 0, canvas_size.cx, canvas_size.cy);
ctx->process_on_resize();
}
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(vao);
ctx->process_on_render();
BOOL swapped = ::SwapBuffers(dc);
if (!swapped)
std::cout << "::SwapBuffers failure, GetLastError() returns " << std::hex << ::GetLastError() << std::endl;
}
ctx->m_program_db.clear();
return EXIT_SUCCESS;
}
It also doesn't cover window creation, it enables OpenGL on an existing window.

Answer 2

This pretty much did it for me: http://nehe.gamedev.net/tutorial/creating_an_opengl_window_%28win32%29/13001/
EDIT: Related code:
/*
* This Code Was Created By Jeff Molofee 2000
* A HUGE Thanks To Fredric Echols For Cleaning Up
* And Optimizing This Code, Making It More Flexible!
* If You've Found This Code Useful, Please Let Me Know.
* Visit My Site At nehe.gamedev.net
*/
#include <windows.h> // Header File For Windows
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
#include <gl\glaux.h> // Header File For The Glaux Library
HDC hDC=NULL; // Private GDI Device Context
HGLRC hRC=NULL; // Permanent Rendering Context
HWND hWnd=NULL; // Holds Our Window Handle
HINSTANCE hInstance; // Holds The Instance Of The Application
bool keys[256]; // Array Used For The Keyboard Routine
bool active=TRUE; // Window Active Flag Set To TRUE By Default
bool fullscreen=TRUE; // Fullscreen Flag Set To Fullscreen Mode By Default
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration For WndProc
GLvoid ReSizeGLScene(GLsizei width, GLsizei height) // Resize And Initialize The GL Window
{
if (height==0) // Prevent A Divide By Zero By
{
height=1; // Making Height Equal One
}
glViewport(0,0,width,height); // Reset The Current Viewport
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
}
int InitGL(GLvoid) // All Setup For OpenGL Goes Here
{
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
return TRUE; // Initialization Went OK
}
int DrawGLScene(GLvoid) // Here's Where We Do All The Drawing
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity(); // Reset The Current Modelview Matrix
return TRUE; // Everything Went OK
}
GLvoid KillGLWindow(GLvoid) // Properly Kill The Window
{
if (fullscreen) // Are We In Fullscreen Mode?
{
ChangeDisplaySettings(NULL,0); // If So Switch Back To The Desktop
ShowCursor(TRUE); // Show Mouse Pointer
}
if (hRC) // Do We Have A Rendering Context?
{
if (!wglMakeCurrent(NULL,NULL)) // Are We Able To Release The DC And RC Contexts?
{
MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
}
if (!wglDeleteContext(hRC)) // Are We Able To Delete The RC?
{
MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
}
hRC=NULL; // Set RC To NULL
}
if (hDC && !ReleaseDC(hWnd,hDC)) // Are We Able To Release The DC
{
MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hDC=NULL; // Set DC To NULL
}
if (hWnd && !DestroyWindow(hWnd)) // Are We Able To Destroy The Window?
{
MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hWnd=NULL; // Set hWnd To NULL
}
if (!UnregisterClass("OpenGL",hInstance)) // Are We Able To Unregister Class
{
MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hInstance=NULL; // Set hInstance To NULL
}
}
/* This Code Creates Our OpenGL Window. Parameters Are: *
* title - Title To Appear At The Top Of The Window *
* width - Width Of The GL Window Or Fullscreen Mode *
* height - Height Of The GL Window Or Fullscreen Mode *
* bits - Number Of Bits To Use For Color (8/16/24/32) *
* fullscreenflag - Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE) */
BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
GLuint PixelFormat; // Holds The Results After Searching For A Match
WNDCLASS wc; // Windows Class Structure
DWORD dwExStyle; // Window Extended Style
DWORD dwStyle; // Window Style
RECT WindowRect; // Grabs Rectangle Upper Left / Lower Right Values
WindowRect.left=(long)0; // Set Left Value To 0
WindowRect.right=(long)width; // Set Right Value To Requested Width
WindowRect.top=(long)0; // Set Top Value To 0
WindowRect.bottom=(long)height; // Set Bottom Value To Requested Height
fullscreen=fullscreenflag; // Set The Global Fullscreen Flag
hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window
wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window.
wc.lpfnWndProc = (WNDPROC) WndProc; // WndProc Handles Messages
wc.cbClsExtra = 0; // No Extra Window Data
wc.cbWndExtra = 0; // No Extra Window Data
wc.hInstance = hInstance; // Set The Instance
wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon
wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer
wc.hbrBackground = NULL; // No Background Required For GL
wc.lpszMenuName = NULL; // We Don't Want A Menu
wc.lpszClassName = "OpenGL"; // Set The Class Name
if (!RegisterClass(&wc)) // Attempt To Register The Window Class
{
MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (fullscreen) // Attempt Fullscreen Mode?
{
DEVMODE dmScreenSettings; // Device Mode
memset(&dmScreenSettings,0,sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared
dmScreenSettings.dmSize=sizeof(dmScreenSettings); // Size Of The Devmode Structure
dmScreenSettings.dmPelsWidth = width; // Selected Screen Width
dmScreenSettings.dmPelsHeight = height; // Selected Screen Height
dmScreenSettings.dmBitsPerPel = bits; // Selected Bits Per Pixel
dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;
// Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
{
// If The Mode Fails, Offer Two Options. Quit Or Use Windowed Mode.
if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
{
fullscreen=FALSE; // Windowed Mode Selected. Fullscreen = FALSE
}
else
{
// Pop Up A Message Box Letting User Know The Program Is Closing.
MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
return FALSE; // Return FALSE
}
}
}
if (fullscreen) // Are We Still In Fullscreen Mode?
{
dwExStyle=WS_EX_APPWINDOW; // Window Extended Style
dwStyle=WS_POPUP; // Windows Style
ShowCursor(FALSE); // Hide Mouse Pointer
}
else
{
dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window Extended Style
dwStyle=WS_OVERLAPPEDWINDOW; // Windows Style
}
AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust Window To True Requested Size
// Create The Window
if (!(hWnd=CreateWindowEx( dwExStyle, // Extended Style For The Window
"OpenGL", // Class Name
title, // Window Title
dwStyle | // Defined Window Style
WS_CLIPSIBLINGS | // Required Window Style
WS_CLIPCHILDREN, // Required Window Style
0, 0, // Window Position
WindowRect.right-WindowRect.left, // Calculate Window Width
WindowRect.bottom-WindowRect.top, // Calculate Window Height
NULL, // No Parent Window
NULL, // No Menu
hInstance, // Instance
NULL))) // Dont Pass Anything To WM_CREATE
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
static PIXELFORMATDESCRIPTOR pfd= // pfd Tells Windows How We Want Things To Be
{
sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
1, // Version Number
PFD_DRAW_TO_WINDOW | // Format Must Support Window
PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
PFD_DOUBLEBUFFER, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
bits, // Select Our 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, // Accumulation Bits Ignored
16, // 16Bit Z-Buffer (Depth Buffer)
0, // No Stencil Buffer
0, // No Auxiliary Buffer
PFD_MAIN_PLANE, // Main Drawing Layer
0, // Reserved
0, 0, 0 // Layer Masks Ignored
};
if (!(hDC=GetDC(hWnd))) // Did We Get A Device Context?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) // Did Windows Find A Matching Pixel Format?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if(!SetPixelFormat(hDC,PixelFormat,&pfd)) // Are We Able To Set The Pixel Format?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if (!(hRC=wglCreateContext(hDC))) // Are We Able To Get A Rendering Context?
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
if(!wglMakeCurrent(hDC,hRC)) // Try To Activate The Rendering Context
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
ShowWindow(hWnd,SW_SHOW); // Show The Window
SetForegroundWindow(hWnd); // Slightly Higher Priority
SetFocus(hWnd); // Sets Keyboard Focus To The Window
ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen
if (!InitGL()) // Initialize Our Newly Created GL Window
{
KillGLWindow(); // Reset The Display
MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}
return TRUE; // Success
}
LRESULT CALLBACK WndProc( HWND hWnd, // Handle For This Window
UINT uMsg, // Message For This Window
WPARAM wParam, // Additional Message Information
LPARAM lParam) // Additional Message Information
{
switch (uMsg) // Check For Windows Messages
{
case WM_ACTIVATE: // Watch For Window Activate Message
{
if (!HIWORD(wParam)) // Check Minimization State
{
active=TRUE; // Program Is Active
}
else
{
active=FALSE; // Program Is No Longer Active
}
return 0; // Return To The Message Loop
}
case WM_SYSCOMMAND: // Intercept System Commands
{
switch (wParam) // Check System Calls
{
case SC_SCREENSAVE: // Screensaver Trying To Start?
case SC_MONITORPOWER: // Monitor Trying To Enter Powersave?
return 0; // Prevent From Happening
}
break; // Exit
}
case WM_CLOSE: // Did We Receive A Close Message?
{
PostQuitMessage(0); // Send A Quit Message
return 0; // Jump Back
}
case WM_KEYDOWN: // Is A Key Being Held Down?
{
keys[wParam] = TRUE; // If So, Mark It As TRUE
return 0; // Jump Back
}
case WM_KEYUP: // Has A Key Been Released?
{
keys[wParam] = FALSE; // If So, Mark It As FALSE
return 0; // Jump Back
}
case WM_SIZE: // Resize The OpenGL Window
{
ReSizeGLScene(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height
return 0; // Jump Back
}
}
// Pass All Unhandled Messages To DefWindowProc
return DefWindowProc(hWnd,uMsg,wParam,lParam);
}
int WINAPI WinMain( HINSTANCE hInstance, // Instance
HINSTANCE hPrevInstance, // Previous Instance
LPSTR lpCmdLine, // Command Line Parameters
int nCmdShow) // Window Show State
{
MSG msg; // Windows Message Structure
BOOL done=FALSE; // Bool Variable To Exit Loop
// Ask The User Which Screen Mode They Prefer
if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
{
fullscreen=FALSE; // Windowed Mode
}
// Create Our OpenGL Window
if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
{
return 0; // Quit If Window Was Not Created
}
while(!done) // Loop That Runs While done=FALSE
{
if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting?
{
if (msg.message==WM_QUIT) // Have We Received A Quit Message?
{
done=TRUE; // If So done=TRUE
}
else // If Not, Deal With Window Messages
{
TranslateMessage(&msg); // Translate The Message
DispatchMessage(&msg); // Dispatch The Message
}
}
else // If There Are No Messages
{
// Draw The Scene. Watch For ESC Key And Quit Messages From DrawGLScene()
if (active) // Program Active?
{
if (keys[VK_ESCAPE]) // Was ESC Pressed?
{
done=TRUE; // ESC Signalled A Quit
}
else // Not Time To Quit, Update Screen
{
DrawGLScene(); // Draw The Scene
SwapBuffers(hDC); // Swap Buffers (Double Buffering)
}
}
if (keys[VK_F1]) // Is F1 Being Pressed?
{
keys[VK_F1]=FALSE; // If So Make Key FALSE
KillGLWindow(); // Kill Our Current Window
fullscreen=!fullscreen; // Toggle Fullscreen / Windowed Mode
// Recreate Our OpenGL Window
if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
{
return 0; // Quit If Window Was Not Created
}
}
}
}
// Shutdown
KillGLWindow(); // Kill The Window
return (msg.wParam); // Exit The Program
}

Answer 3

If you really, really want to do it yourself, you can still have a look at how GLFW does it. In its source directory, you have a win32-specific directory, in which you have a windowing-specic .c file. You should find everything you need in this file.
This page of the OpenGL Wiki could help you, too.

Answer 4

The best way is NOT to do it yourself. OpenGL context creation is a bottomless abyss of complexity. You have lots of tools that can do the dirty work for you, and what's more, it'll work on Linux and Mac too
GLFW, FreeGlut, SDL, SFML are probably the most common.
See GLFW's user guide, for instance, to see how easy these libs make it to create a window :
glfwInit();
glfwOpenWindow( 300,300, 0,0,0,0,0,0, GLFW_WINDOW );
// bam, you're done