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 [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
