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AverageJoeSSU

OpenGL Pros/Cons of using WM_PAINT for rendering

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IMHO:
WM_PAINT for rendering ONLY when you don't have to update continuously: only when events (window messages) occur. Most games have to be updated repeatedly, so you have to render "outside" the message handling loop. So not in WM_PAINT.

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The problem with Windows messaging functions is that there is no guarantee of when the message will arrive at your application. So there will definitely be some latency between the time when your window needs to be redrawn and the time when your app gets the WM_PAINT and is actually redrawn. How long that is depends on a variety of factors, many of which are completely outside of the control of your app (some AV software might be hooking and examining all Windows messages for all apps as part of it's heuristics, for example). So what runs fast on one machine might be unacceptably slow on another.

You're better off writing a proper game loop (using PeekMessage instead of GetMessage) and doing your rendering in that.

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Yeah... i agree... so i currently have a peek message loop implemented, but am not sure how the device context lives through the application.

For some reason my device context gets lost (even with using OWN_DC).

I am running out of ideas as to why this is happening.

When using the WM_PAINT, you get difference DC's throughout your application.

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Post code. Do you store all the handlers during the lifespan of the program (window, device, rendering context) and use them? Do you create the window/device/rendering context in the appropriate order?
RegisterClass(...)
MainWindow.hWnd=CreateWindowEx(...);
ShowWindow(...);

MainWindow.hDC = GetDC(MainWindow.hWnd);

PixelFormat = ChoosePixelFormat(MainWindow.hDC,&pfd);
SetPixelFormat(MainWindow.hDC,PixelFormat,&pfd);
MainWindow.hRC = wglCreateContext(MainWindow.hDC);
wglMakeCurrent(MainWindow.hDC,MainWindow.hRC);

OpenGLInitStuff();

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Ha... your code is unbelievably simplified.

I will refactor mine before i post my mess of code.

EDIT: It's actually not that bad... most of it is from the tuts.


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

this->m_hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window
wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC | CS_GLOBALCLASS; // Redraw On Size, And Own DC For Window.
wc.lpfnWndProc = (WNDPROC) WndPDummy;// WndProc Handles Messages
wc.cbClsExtra = 0; // No Extra Window Data
wc.cbWndExtra = 0; // No Extra Window Data
wc.hInstance = this->m_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 = _T("OpenGL"); // Set The Class Name

if (!RegisterClass(&wc)) // Attempt To Register The Window Class
{
MessageBox(NULL,_T("Failed To Register The Window Class."),_T("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,_T("The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?"),_T("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,_T("Program Will Now Close."),_T("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 (!(m_hDevWindow=CreateWindowEx( dwExStyle, // Extended Style For The Window
_T("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
m_hInstance, // Instance
NULL))) // Dont Pass Anything To WM_CREATE
{
// Retrieve the system error message for the last-error code
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Window Creation Error."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

hookWindow(m_hDevWindow);

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
32, // 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(m_hDevWindow))) // Did We Get A Device Context?
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Can't Create A GL Device Context."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) // Did Windows Find A Matching Pixel Format?
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Can't Find A Suitable PixelFormat."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

if(!SetPixelFormat(hDC,PixelFormat,&pfd)) // Are We Able To Set The Pixel Format?
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Can't Set The PixelFormat."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

if (!(hRC=wglCreateContext(hDC))) // Are We Able To Get A Rendering Context?
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Can't Create A GL Rendering Context."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

if(!wglMakeCurrent(hDC,hRC)) // Try To Activate The Rendering Context
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Can't Activate The GL Rendering Context."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

ShowWindow(m_hDevWindow,SW_SHOW); // Show The Window
SetForegroundWindow(m_hDevWindow); // Slightly Higher Priority
SetFocus(m_hDevWindow); // Sets Keyboard Focus To The Window
this->ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen


if (!this->OnInit()) // Initialize Our Newly Created GL Window
{
this->Shutdown(); // Reset The Display
MessageBox(NULL,_T("Initialization Failed."),_T("ERROR"),MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE
}

this->soundMan.Init();
// load stolen windows sound for now
//this->soundMan.Load("..\\Content\\Sounds\\type.wav", false);
this->AssetMgr->GetSound("..\\Content\\Sounds\\type.wav", false, &this->soundMan);

this->lastTime = timeGetTime();
return TRUE;





and on shutdown, you can see where i get the 1425 error code

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(hDC,NULL)) // Are We Able To Release The DC And RC Contexts?
{
MessageBox(NULL,_T("Release Of DC And RC Failed."),_T("SHUTDOWN ERROR"),MB_OK | MB_ICONINFORMATION);
}

if (!wglDeleteContext(hRC)) // Are We Able To Delete The RC?
{
MessageBox(NULL,_T("Release Rendering Context Failed."),_T("SHUTDOWN ERROR"),MB_OK | MB_ICONINFORMATION);
}
hRC=NULL; // Set RC To NULL
}

bool Released = ReleaseDC(m_hDevWindow,hDC);
DWORD errr = GetLastError();
if (hDC && !Released) // Are We Able To Release The DC
{
MessageBox(NULL,_T("Release Device Context Failed."),_T("SHUTDOWN ERROR"),MB_OK | MB_ICONINFORMATION);
hDC=NULL; // Set DC To NULL
}
bool R = DestroyWindow(m_hDevWindow);
DWORD errrr = GetLastError();
if (m_hDevWindow && !DestroyWindow(m_hDevWindow)) // Are We Able To Destroy The Window?
{
MessageBox(NULL,_T("Could Not Release hWnd."),_T("SHUTDOWN ERROR"),MB_OK | MB_ICONINFORMATION);
m_hDevWindow=NULL; // Set hWnd To NULL
}

if (!UnregisterClass(_T("OpenGL"),m_hInstance)) // Are We Able To Unregister Class
{
MessageBox(NULL,_T("Could Not Unregister Class."),_T("SHUTDOWN ERROR"),MB_OK | MB_ICONINFORMATION);
m_hInstance=NULL; // Set hInstance To NULL
}




return S_OK;




[Edited by - AverageJoeSSU on October 18, 2010 12:05:40 AM]

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Nope. Pay attention to the order that I posted!

You have to ShowWindow before you get the device. When I did it just like you do, I got very strange and seemingly unrelated bugs. With fonts for example. My code is simplified but that should be just enough.

The order is very important!!

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I have never experienced loosing DC. Even when changing the resolution.

How do you know you loose it? Post the WindProc too.

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So,

I removed my "doOpenGLInit" function and went straight to shutdown, and it works correctly.

I am doing some weirdness for hooking in my WndProc which allows me to intialize my engine from a hwnd parameter.

http://msdn.microsoft.com/en-us/library/ms633591(VS.85).aspx

I think i am doing this incorrectly. (at least not correct enough to release).

I'll post some code when i am home.

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      I literally can't find what is wrong. If you need more code, ask me to post it. I will also attach all the source files.
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      Error.cpp
      IndexBuffer.cpp
      Input.cpp
      Renderer.cpp
      Scene.cpp
      Shader.cpp
      Sprite.cpp
      Texture.cpp
      VertexArray.cpp
      VertexBuffer.cpp
      VertexBufferLayout.cpp
      Window.cpp
      Brain.h
      Error.h
      IndexBuffer.h
      Input.h
      Renderer.h
      Scene.h
      Shader.h
      SpaceShooterEngine.h
      Sprite.h
      Texture.h
      VertexArray.h
      VertexBuffer.h
      VertexBufferLayout.h
      Window.h
    • By Cristian Decu
      Hello fellow programmers,
      For a couple of days now i've decided to build my own planet renderer just to see how floating point precision issues
      can be tackled. As you probably imagine, i've quickly faced FPP issues when trying to render absurdly large planets.
       
      I have used the classical quadtree LOD approach;
      I've generated my grids with 33 vertices, (x: -1 to 1, y: -1 to 1, z = 0).
      Each grid is managed by a TerrainNode class that, depending on the side it represents (top, bottom, left right, front, back),
      creates a special rotation-translation matrix that moves and rotates the grid away from the origin so that when i finally
      normalize all the vertices on my vertex shader i can get a perfect sphere.
      T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, 1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(180.0), glm::dvec3(1.0, 0.0, 0.0)); sides[0] = new TerrainNode(1.0, radius, T * R, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_FRONT)); T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, -1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(0.0), glm::dvec3(1.0, 0.0, 0.0)); sides[1] = new TerrainNode(1.0, radius, R * T, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_BACK)); // So on and so forth for the rest of the sides As you can see, for the front side grid, i rotate it 180 degrees to make it face the camera and push it towards the eye;
      the back side is handled almost the same way only that i don't need to rotate it but simply push it away from the eye.
      The same technique is applied for the rest of the faces (obviously, with the proper rotations / translations).
      The matrix that result from the multiplication of R and T (in that particular order) is send to my vertex shader as `r_Grid'.
      // spherify vec3 V = normalize((r_Grid * vec4(r_Vertex, 1.0)).xyz); gl_Position = r_ModelViewProjection * vec4(V, 1.0); The `r_ModelViewProjection' matrix is generated on the CPU in this manner.
      // No the most efficient way, but it works. glm::dmat4 Camera::getMatrix() { // Create the view matrix // Roll, Yaw and Pitch are all quaternions. glm::dmat4 View = glm::toMat4(Roll) * glm::toMat4(Pitch) * glm::toMat4(Yaw); // The model matrix is generated by translating in the oposite direction of the camera. glm::dmat4 Model = glm::translate(glm::dmat4(1.0), -Position); // Projection = glm::perspective(fovY, aspect, zNear, zFar); // zNear = 0.1, zFar = 1.0995116e12 return Projection * View * Model; } I managed to get rid of z-fighting by using a technique called Logarithmic Depth Buffer described in this article; it works amazingly well, no z-fighting at all, at least not visible.
      Each frame i'm rendering each node by sending the generated matrices this way.
      // set the r_ModelViewProjection uniform // Sneak in the mRadiusMatrix which is a matrix that contains the radius of my planet. Shader::setUniform(0, Camera::getInstance()->getMatrix() * mRadiusMatrix); // set the r_Grid matrix uniform i created earlier. Shader::setUniform(1, r_Grid); grid->render(); My planet's radius is around 6400000.0 units, absurdly large, but that's what i really want to achieve;
      Everything works well, the node's split and merge as you'd expect, however whenever i get close to the surface
      of the planet the rounding errors start to kick in giving me that lovely stairs effect.
      I've read that if i could render each grid relative to the camera i could get better precision on the surface, effectively
      getting rid of those rounding errors.
       
      My question is how can i achieve this relative to camera rendering in my scenario here?
      I know that i have to do most of the work on the CPU with double, and that's exactly what i'm doing.
      I only use double on the CPU side where i also do most of the matrix multiplications.
      As you can see from my vertex shader i only do the usual r_ModelViewProjection * (some vertex coords).
       
      Thank you for your suggestions!
       
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