Re: [osg-users] GL_STENCIL_TEST in draw implementation callback
afaik there are implementation dependent restrictions on viewport size, you may hitting those limits 16.03.2012, 19:14, Doug Domke doug.do...@boeing.com: UGH! I just found that I was mistaken about the video growing properly without the stencil. It actually doesn't. Once its viewport exceeds a certain size, it no longer renders as expected. I think I've come as far as I can here. Thanks anyway. Doug -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46353#46353 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] GL_STENCIL_TEST in draw implementation callback
Clearing the modelview and projection matrices helped a great deal. Thanks hybr! It now works as intended ... up to a point that is difficult to explain. I get the digital zoom effect until about 13x. At that point, the video suddenly starts translating instead of zooming. And instead of showing video that is off-center (which would still be confusing and wrong to me since there is nothing that is doing a translation), the video is still clipped such that inside my stencil quad I see a repeat of other items in the application (I get buttons and such drawing in my video quad). If I disable the GL_STENCIL_TEST now, the video viewport grows exactly as expected. At some point, it does grow beyond the size of my application window. Perhaps this is a problem for the stencil for some reason? Can anyone provide additional insight for me? Thanks again! Doug -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46349#46349 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] GL_STENCIL_TEST in draw implementation callback
UGH! I just found that I was mistaken about the video growing properly without the stencil. It actually doesn't. Once its viewport exceeds a certain size, it no longer renders as expected. I think I've come as far as I can here. Thanks anyway. Doug -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46353#46353 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] GL_STENCIL_TEST in draw implementation callback
Hi, We have an OSG-based application that uses a 3rd party library to draw video. We want my application to perform a digital zoom on this video. Given the API to this library, we wrote an OSG node with a draw callback that calculates the viewport for the video to draw in, and lets the library do its magic. My theory for the digital zoom feature is to give the library a larger viewport (it always draws the same scene into the viewport) and cull/clip/stencil the result. My current attempt is in using a glStencil in the draw callback as follows: Code: glEnable(GL_STENCIL_TEST); glClear(GL_STENCIL_BUFFER_BIT); glStencilFunc(GL_ALWAYS, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glBegin(GL_QUADS); glVertex2d(left, bottom); glVertex2d(left, top); glVertex2d(right, top); glVertex2d(right, bottom); glEnd(); glStencilFunc(GL_EQUAL, 1, 1); draw video glDisable(GL_STENCIL_TEST); Unfortunately, the video ends up disappearing entirely. If I remove the Code: glEnable(GL_STENCIL_TEST); line, the video draws in the larger viewport and overlaps areas that it shouldn't. Can anyone identify a flaw in my code? Is there another approach that may be better? Thank you! -Doug[/code] -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46318#46318 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] GL_STENCIL_TEST in draw implementation callback
Hi Are you sure your quad not being rejected by depth test? Also as it being drawn with fixed finction, modelview and projection matrices set by osg for opengl state are affecting your quad drawing. So easy\dirty way is to attach shader which calc vertex position without using gl_ModelViewMatrix and gl_ProjectionMatrix, and disable GL_DEPTH_TEST when quad is drawn if needed. You can avoid most of pure opengl code, if you will use osg::Projection(set to whatever projection your quad needs to be)- osg::MatrixTransform(set to identity and with ABSOLUTE_RF reference frame)- osg::ClearNode(set up to clear stencil buffer)- Geode containing your quad with correct osg::Stencil stuff setup in stateset. You can skip projection and matrixtransform if you use shader mentioned above. Then you add drawCallback to your quad, where you call quad's default drawImplementation() glEnable(GL_STENCIL_TEST); glStencilFunc(GL_EQUAL, 1, 1); draw video glDisable(GL_STENCIL_TEST); 16.03.2012, 00:01, Doug Domke doug.do...@boeing.com: Hi, We have an OSG-based application that uses a 3rd party library to draw video. We want my application to perform a digital zoom on this video. Given the API to this library, we wrote an OSG node with a draw callback that calculates the viewport for the video to draw in, and lets the library do its magic. My theory for the digital zoom feature is to give the library a larger viewport (it always draws the same scene into the viewport) and cull/clip/stencil the result. My current attempt is in using a glStencil in the draw callback as follows: Code: glEnable(GL_STENCIL_TEST); glClear(GL_STENCIL_BUFFER_BIT); glStencilFunc(GL_ALWAYS, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glBegin(GL_QUADS); glVertex2d(left, bottom); glVertex2d(left, top); glVertex2d(right, top); glVertex2d(right, bottom); glEnd(); glStencilFunc(GL_EQUAL, 1, 1); draw video glDisable(GL_STENCIL_TEST); Unfortunately, the video ends up disappearing entirely. If I remove the Code: glEnable(GL_STENCIL_TEST); line, the video draws in the larger viewport and overlaps areas that it shouldn't. Can anyone identify a flaw in my code? Is there another approach that may be better? Thank you! -Doug[/code] -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46318#46318 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] GL_STENCIL_TEST in draw implementation callback
Hi Doug, How exactly is this library drawing the video? Is it feeding the video data into a texture, and applying that texture onto a simple quad? If so, it seems like the best approach would be to use the osg::TexMat class to transform the texture coordinates of the quad to simulate a zooming in effect. Either way, it's difficult to say what is going wrong without knowing more about how this library works. Cheers, Farshid On Thu, Mar 15, 2012 at 1:01 PM, Doug Domke doug.do...@boeing.com wrote: Hi, We have an OSG-based application that uses a 3rd party library to draw video. We want my application to perform a digital zoom on this video. Given the API to this library, we wrote an OSG node with a draw callback that calculates the viewport for the video to draw in, and lets the library do its magic. My theory for the digital zoom feature is to give the library a larger viewport (it always draws the same scene into the viewport) and cull/clip/stencil the result. My current attempt is in using a glStencil in the draw callback as follows: Code: glEnable(GL_STENCIL_TEST); glClear(GL_STENCIL_BUFFER_BIT); glStencilFunc(GL_ALWAYS, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glBegin(GL_QUADS); glVertex2d(left, bottom); glVertex2d(left, top); glVertex2d(right, top); glVertex2d(right, bottom); glEnd(); glStencilFunc(GL_EQUAL, 1, 1); draw video glDisable(GL_STENCIL_TEST); Unfortunately, the video ends up disappearing entirely. If I remove the Code: glEnable(GL_STENCIL_TEST); line, the video draws in the larger viewport and overlaps areas that it shouldn't. Can anyone identify a flaw in my code? Is there another approach that may be better? Thank you! -Doug[/code] -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=46318#46318 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
