Hello out there, please help,

I am writing a windows service-application (no visible window), that
renders a scene with opengl and writes pictures out. Rendered things
come out, but the stencil buffer does not work. I am rendering a 3D
scene and then drawing a background with drawpixels. Drawpixels should
not draw where any 3d things are drawn. This method works well with
PFD_DRAW_TO_WINDOW and doublebuffering. In the bitmap setup drawpixels
draws everywhere (overwriting the rendered scene). I take the picture by
using glReadPixels. Thanks for helping, Peter

Here my pfd setup:
static PIXELFORMATDESCRIPTOR pfd = {
    sizeof(PIXELFORMATDESCRIPTOR),            // Size of this structure
      1,                                      // Version of this
structure
      PFD_DRAW_TO_BITMAP |                    // Draw to bitmap
      PFD_SUPPORT_OPENGL |
      PFD_SUPPORT_GDI,
      PFD_TYPE_RGBA,                          // RGBA Color mode
      m_BitsPerPixel,                                   // Want 24bit
color
      0,0,0,0,0,0,                            // Color bits ignored
      0,0,                                    // No alpha buffer
      0,0,0,0,0,                              // Shift bits ignored
      16,                                     // Size of depth buffer
      16,           //16-bit stencil buffer
      0,                                      // no auxiliary buffer
      PFD_MAIN_PLANE,                         // Draw in main plane
      0,                                      // reserved
      0,0,0         // layer masks ignored
 };

Here my stencil setup:

glEnable(GL_STENCIL_TEST | GL_DEPTH_TEST);

//if zbuffertest is passed then write 1 to stencil buffer
 glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);

// Clear out the color, stencil & depth buffers
 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT |
GL_STENCIL_BUFFER_BIT);

 //renderfirst setting stencil
 //stencil test is always passed
 glStencilFunc(GL_ALWAYS, 1, 1);
 render3D();

 //drawvideo where stencil isn't set to 1
 glStencilFunc (GL_NOTEQUAL, 1, 1);
  //video changes projection setup, we safe current projection
 glMatrixMode(GL_PROJECTION);
 glPushMatrix();
 render2D();

//return to 3D Projection
glMatrixMode(GL_PROJECTION);
 glPopMatrix();
 glMatrixMode(GL_MODELVIEW);

--
Dipl.-Ing. Peter Meier
Phone:  +49 (0)89 289 15570
Fax:    +49 (0)89 289 15555

Institut für Werkzeugmaschinen und Betriebswissenschaften (iwb)
Prof. Dr.-Ing. M. Zäh
Prof. Dr.-Ing. G. Reinhart
TU Muenchen

peter.me...@iwb.tum.de
http://www.iwb.tum.de

<snip>

Try switching from 24bpp to 32bpp..

Hello, thanks a lot for the reply, but I just now found the error.
Unfortunately I know what I dit to fix it, but I do not know why it works now.
Apparently there must have been some openGL calls in some lib, that screwed up
my stencil function. I just repeated the call at another place and now it
works.

See ya, Peter

Jerker Olofsson schrieb:

--
Dipl.-Ing. Peter Meier
Phone:  +49 (0)89 289 15570
Fax:    +49 (0)89 289 15555

Institut für Werkzeugmaschinen und Betriebswissenschaften (iwb)
Prof. Dr.-Ing. M. Zäh
Prof. Dr.-Ing. G. Reinhart
TU Muenchen

peter.me...@iwb.tum.de
http://www.iwb.tum.de