Draw OpenGLScene without WM_PAINT - comp.graphics.api.opengl

Hi all, I'm writing a software that receive data to USB port and draw same graphics in same Windows TAB ( I'm using Visual Studio 2003 with MFC ). I have to draw the new scene only when the new data on USB port is available and this data changing is not very fast (400 Hz - 400 sample per second), on this I have an issue with the extra work to CPU, is always upper than 90% probably because the WM_PAINT is so fast and the software draws continuosly the same scene between two sample to USB port. To solve this issue I tried to eliminate the WM_PAINT in OpenGL and call the OpenGL::OnPaint only when the new data occours but the window's device context is 0 and I don't understand why. Cau yuo help me? Thank you Alberto

Albe wrote: > Hi all, > I'm writing a software that receive data to USB port and draw > same graphics in same Windows TAB ( I'm using Visual Studio > 2003 with MFC ). > I have to draw the new scene only when the new data on USB port > is available and this data changing is not very fast (400 Hz - > 400 sample per second), on this I have an issue with the extra > work to CPU, is always upper than 90% probably because the > WM_PAINT is so fast and the software draws continuosly the same > scene between two sample to USB port. > > To solve this issue I tried to eliminate the WM_PAINT in OpenGL > and call the OpenGL::OnPaint only when the new data occours but > the window's device context is 0 and I don't understand why. > > Cau yuo help me? I don't know (anymore) why the DC in a manually issuied WM_PAINT may be 0, however rest assured, that it doesn't matter to you: Once created, the OpenGL context is independent of any DC, you just have to make sure it's been made current (wglMakeCurrent). Then you may use the context (i.e. render stuff) whenever you see fit. Wolfgang Draxinger -- E-Mail address works, Jabber: hexarith@jabber.org, ICQ: 134682867

Hi Wolfgang, thank you for reply but I'm sorry I don't understand your message, I'm a newbie in OpenGL and I'm no expert in context ecc ecc... Just to be clear, I'm using this code OGLPlo = new COpenGLControl(); .... CString className = AfxRegisterWndClass(CS_HREDRAW | CS_VREDRAW | CS_OWNDC,NULL,(HBRUSH)StockObject(BLACK_BRUSH),NULL); CreateEx( 0,className,"OpenGL",WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN, rect,parent,0); .... dc = new CClientDC(this); .... openGLDevice.create(dc->m_hDC); bool OpenGLDevice::create(HDC& deviceContext,int stencil) { if (!deviceContext) { return false; } if (!setDCPixelFormat(deviceContext,stencil)) { return false; } renderContext = wglCreateContext(deviceContext); wglMakeCurrent(deviceContext, renderContext); OpenGLDevice::deviceContext = deviceContext; return true; } .... "COpenGLControl::InitGL" .... "COpenGLControl::OnSize" .... <---- ERROR dc=0 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); .... Disegna_Barre(); .... SwapBuffers(dc->m_hDC); Here there are the main instruction used to create the OpenGL windows, it works fine in normal way (when the OnPaint is called from WM_PAINT) but when I try to call OnPaint without WM_PAINT (I'm calling OnPaint from a function inside the ogl class each time a new data is available) the dc is ok before the OnPaint calling, after the dc=0 and an error occours in SwapBuffers(dc->m_hDC); I hope make clear, thank you in advance Alberto

On May 19, 11:47=A0am, Albe <alberto_res...@tiscali.it> wrote: > Hi Wolfgang, thank you for reply but I'm sorry I don't understand your > message, I'm a newbie in OpenGL and I'm no expert in context ecc > ecc... > Just to be clear, I'm using this code > > OGLPlo =3D new COpenGLControl(); > ... > CString className =3D AfxRegisterWndClass(CS_HREDRAW | CS_VREDRAW | > CS_OWNDC,NULL,(HBRUSH)StockObject(BLACK_BRUSH),NULL); > > CreateEx( =A0 =A0 =A0 0,className,"OpenGL",WS_CHILD | WS_VISIBLE | WS_CLIP= SIBLINGS > | WS_CLIPCHILDREN, > rect,parent,0); > ... > dc =3D new CClientDC(this); > ... > openGLDevice.create(dc->m_hDC); > > bool OpenGLDevice::create(HDC& deviceContext,int stencil) > { > =A0 =A0 =A0 =A0 if (!deviceContext) > =A0 =A0 =A0 =A0 { > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false; > =A0 =A0 =A0 =A0 } > > =A0 =A0 =A0 =A0 if (!setDCPixelFormat(deviceContext,stencil)) > =A0 =A0 =A0 =A0 { > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return false; > =A0 =A0 =A0 =A0 } > > =A0 =A0 =A0 =A0 renderContext =3D wglCreateContext(deviceContext); > =A0 =A0 =A0 =A0 wglMakeCurrent(deviceContext, renderContext); > > =A0 =A0 =A0 =A0 OpenGLDevice::deviceContext =3D deviceContext; > > =A0 =A0 =A0 =A0 return true;} > > ... > "COpenGLControl::InitGL" > ... > "COpenGLControl::OnSize" > ... =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <---- =A0ERROR dc=3D0 > glClear(GL_COLOR_BUFFER_BIT =A0 =A0 =A0| =A0GL_DEPTH_BUFFER_BIT); > glLoadIdentity(); > ... > Disegna_Barre(); > ... > SwapBuffers(dc->m_hDC); > > Here there are the main instruction used to create the OpenGL windows, > it works fine in normal way (when the OnPaint is called from WM_PAINT) > but when I try to call OnPaint without WM_PAINT (I'm calling OnPaint > from a function inside the ogl class each time a new data is > available) the dc is ok before the OnPaint calling, after the dc=3D0 and > an error occours in > > SwapBuffers(dc->m_hDC); > > I hope make clear, thank you in advance > > Alberto Don't sweat over the paint messages, they are just artifact of Microsoft's aged window manager. The window manager doesn't keep a copy of the canvas contents so any time new portions of window are revealed the window manager has to ask the application to (re-)generate the content. This is done much better on modern window managers, but that doesn't help you much since it appears you are using the GDI (not a bad choise since it caters for more flavours of windows than just the latest Vista incarnations). What you want to do is to beginpaint, do your rendering, endpaint and repeat that as often as required. If you use FBO's and render-to- texture, you can use the framebuffer object for the paint messages. This would go into the category of useless optimizations as you need a good performance (or so I would be inclined to guess) to begin with. Might help with lower performance systems if you don't update the image too frequently, go figure, could depend on how complex your dataset is. I didn't catch what you meant by 400 Hz, you want to update the scene every time a new sample arrives, or batch updates? It will be rather difficult to display your "signal" at 400 Hz, so it would make sense to display snapshots of the data after specific time has elapsed for example. This is kind of embarassingly trivial stuff but since you are asking I'm forced to assume that there is something unstated in your question. Care to be more specific what kind of trouble you are experiencing again?

Hi aku ankka, my problem is that when the software shows the OpenGL the CPU works around at 100% and I have to decrease this usage. I saw that if I insert in the cycle the instruction Sleep(1) the CPU-usage decrease around 30% and it's right but the issue is that the time to draw a scene is longer than the time between two sample and, in this case, the software buffer the data. My idea was to call the OnPaint only when a new data occours.

Albe wrote: > Hi aku ankka, > my problem is that when the software shows the OpenGL the CPU works > around at 100% and I have to decrease this usage. I saw that if I > insert in the cycle the instruction > > Sleep(1) > > the CPU-usage decrease around 30% and it's right but the issue is that > the time to draw a scene is longer than the time between two sample > and, in this case, the software buffer the data. > > My idea was to call the OnPaint only when a new data occours. You shouldn't call OnPaint directly (or send WM_PAINT). Instead, call InvalidateRect to tell Windows that you window needs redrawing. Then Windows will post a WM_PAINT message. Call UpdateWindow if you want the window to update immediately.

Albe wrote: > Ok Jonno, > in the message manage I have deleted the WM_PAINT -> OnPaint in opengl > class and for each new data I call UpdateWindows, unfortunatly the > software don't draw the opengl windows. > > :( You still need the WM_PAINT message handler. You wrote: > I'm calling OnPaint from a function inside the ogl class each time a new data is > available Don't call OnPaint, call InvalidateRect (and optionally UpdateWindow) instead.

Hi Jonno, probably owing to my bad english I did't explain correctly my problem: I have an application named EKXXX with 3 classes CEKXXXApp CEKXXXDlg COpenGLControl in CEKXXXDlg there is a function named OnPaint associate at WM_PAINT message and is void CEKXXXDlg::OnPaint() { CPaintDC dc(this); // device context for painting if (IsIconic()) { SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0); // Center icon in client rectangle int cxIcon = GetSystemMetrics(SM_CXICON); int cyIcon = GetSystemMetrics(SM_CYICON); CRect rect; GetClientRect(&rect); int x = (rect.Width() - cxIcon + 1) / 2; int y = (rect.Height() - cyIcon + 1) / 2; // Draw the icon dc.DrawIcon(x, y, m_hIcon); } else { CDialog::OnPaint(); } } in COpenGLControl there is a function named OnPaint associate at WM_PAINT message and is void COpenGLControl::OnPaint() { if(*datoOK) { /** OpenGL section **/ openGLDevice.makeCurrent(); DrawGLScene(); *datoOK=false; temp_stato_old=tab; } } When the software don't show opengl (there are two tab, in the first there is a text box with the program description, in the second there is an opengl windows that draw the data received from USB) the CPU usage is about 10%, when the opengl is showed the CPU usage is about 98%, MORE. I think that WM_PAINT is the same windows message and when it comes the software runs OnPaint in CEKXXXDlg and OnPaint in COpenGLControl. I can't use Sleep(x) becuse the system became too late, how I can do to decrease CPU usage when the software shows OpenGL windows??? Sorry and thank you Alberto

> void COpenGLControl::OnPaint() > { > if(*datoOK) > { > /** OpenGL section **/ > > openGLDevice.makeCurrent(); > DrawGLScene(); > *datoOK=false; > > temp_stato_old=tab; > } > } You're not validating your window here. You need this line: CPaintDC dc(this); Even though you don't use the DC, the CPaintDC constructor calls BeginPaint which tells Windows you have handled the WM_PAINT message. Otherwise it will just keep sending more WM_PAINTs.

On May 19, 3:57=A0pm, Albe <alberto_res...@tiscali.it> wrote: > Hi aku ankka, > my problem is that when the software shows the OpenGL the CPU works > around at 100% and I have to decrease this usage. I saw that if I > insert in the cycle the instruction > > Sleep(1) > > the CPU-usage decrease around 30% and it's right but the issue is that > the time to draw a scene is longer than the time between two sample > and, in this case, =A0the software buffer the data. It doesn't benefit you to render faster than the refresh rate of the display; rendering snapshots of the data shouldn't be a problem. You got me hooked already, what's the data?

I agree aku ankka, it doesn't benefit render faster than the refresh rate of the display, I have to refresh only when a new data occours but the WM_PAINT message is faster than the data. I have associated the high CPU usage with the faster WM_PAINT message, I'm not sure that it is correct, I tried to eliminate the WM_PAINT function in OpenGLControl::OnPaint and the CPU usage decrease to 15-25%, I tried to comment the code in OpenGLControl::OnPaint (I create the openglwindows but I don't draw aniting) the CPU usage stay to 95-98%. To USB I read a serial data composed to 10 bytes, the time betwenn two samples is settable at 50 Hz, 100Hz, 400Hz and 1000Hz. My driver maximum speed is 600 Hz (I have same problem when the device write at 1000 Hz but is not my priority now). Thank you for support

On May 20, 4:25 am, Albe <alberto_res...@tiscali.it> wrote: > I agree aku ankka, it doesn't benefit render faster than the refresh > rate of the display, I have to refresh only when a new data occours > but the WM_PAINT message is faster than the data. I have associated > the high CPU usage with the faster WM_PAINT message, I'm not sure that > it is correct, I tried to eliminate the WM_PAINT function in > OpenGLControl::OnPaint and the CPU usage decrease to 15-25%, I tried > to comment the code in OpenGLControl::OnPaint (I create the > openglwindows but I don't draw aniting) the CPU usage stay to 95-98%. > > To USB I read a serial data composed to 10 bytes, the time betwenn two > samples is settable at 50 Hz, 100Hz, 400Hz and 1000Hz. My driver > maximum speed is 600 Hz (I have same problem when the device write at > 1000 Hz but is not my priority now). > > Thank you for support you must be pooling when reading from USB can you switch to a blocking I/O ? this will save CPU resources a lot

On 21 Mag, 18:33, Diego <jose.di...@gmail.com> wrote: > On May 20, 4:25 am, Albe <alberto_res...@tiscali.it> wrote: > > > I agree aku ankka, it doesn't benefit render faster than the refresh > > rate of the display, I have to refresh only when a new data occours > > but the WM_PAINT message is faster than the data. I have associated > > the high CPU usage with the faster WM_PAINT message, I'm not sure that > > it is correct, I tried to eliminate the WM_PAINT function in > > OpenGLControl::OnPaint and the CPU usage decrease to 15-25%, I tried > > to comment the code in OpenGLControl::OnPaint (I create the > > openglwindows but I don't draw aniting) the CPU usage stay to 95-98%. > > > To USB I read a serial data composed to 10 bytes, the time betwenn two > > samples is settable at 50 Hz, 100Hz, 400Hz and 1000Hz. My driver > > maximum speed is 600 Hz (I have same problem when the device write at > > 1000 Hz but is not my priority now). > > > Thank you for support > > you must be pooling when reading from USB > can you switch to a blocking I/O ? this will save CPU resources a lot My problem is to control the WM_PAINT, this message arrives also when the data is not available and this probably overload the CPU

> My problem is to control the WM_PAINT, this message arrives also when > the data is not available and this probably overload the CPU I already told you how to fix this. Add this line to COpenGLControl::OnPaint()... CPaintDC dc(this); Otherwise Windows will keep sending more WM_PAINT messages.

"Albe" <alberto_ressia@tiscali.it> schrieb im Newsbeitrag news:53f0110b-6d35-4e32-9a57-8c7834c86e19@d1g2000hsg.googlegroups.com... > Hi all, > I'm writing a software that receive data to USB port and draw same > graphics in same Windows TAB ( I'm using Visual Studio 2003 with > MFC ). > I have to draw the new scene only when the new data on USB port is > available and this data changing is not very fast (400 Hz - 400 sample > per second), on this I have an issue with the extra work to CPU, is > always upper than 90% probably because the WM_PAINT is so fast and the > software draws continuosly the same scene between two sample to USB > port. The problem with 90% CPU power and unneeded draws is that a bug in command sequence. Use one of these - ValidateRect() - DefWindowProc() - [MFC] CWnd::OnPaint() to stop WM_PAINT sending until new content. Use InvalidateRect() to refresh area. Do not send manual WM_PAINT with SendEvent() !! > > To solve this issue I tried to eliminate the WM_PAINT in OpenGL and > call the OpenGL::OnPaint only when the new data occours but the > window's device context is 0 and I don't understand why. > > Cau yuo help me? > > Thank you > > Alberto Hope this helps. Clemens

Hi Clemens, thak you very much for reply, probably I understand your suggestion, I have implemented new instruction in the code void COpenGLControl::OnPaint() { if(*datoOK) { InvalidateRect(Prova, true); openGLDevice.makeCurrent(); DrawGLScene(); *datoOK=false; temp_stato_old=tab; } else { ValidateRect(Prova); } } "Prova" is CRect ogl windows where i draw with "DrawGLScene" My idea based on Clemens's suggestion is that when the new data is available I use InvalidateRect and when windows call WM_PAINT but the data is not availabe I use ValidateRect. Unfortunally, with this code the ogl is freezed, probably I don't use correctly InvalidateRect.

Albe wrote: > Hi Clemens, > thak you very much for reply, probably I understand your suggestion, I > have implemented new instruction in the code > > void COpenGLControl::OnPaint() > { > if(*datoOK) > { > InvalidateRect(Prova, true); > openGLDevice.makeCurrent(); > DrawGLScene(); > *datoOK=false; > temp_stato_old=tab; > } > else > { > ValidateRect(Prova); > } > > } Try this: void COpenGLControl::OnPaint() { openGLDevice.makeCurrent(); DrawGLScene(); ValidateRect(Prova); } When you want to redraw, call InvalidateRect(Prova, true);