Hello Richard, > Being able to render something last... that could be useful. But I'm > thinking I want to render the skydome _first_, using a "painters > algorithm" and drawing everything else in front of it. It seems this > would also be the best approach for a rendering a night time sky using > point sprites for the stars, etc.
Why do you want to render it first, and then have it be overwritten by your objects, which might (worst case) result in having drawn the whole screen twice for nothing? Render it last, but only setting pixels at the far plane. That way, pixels that contain other objects will not be overwritten by your skydome. For example, this is from the skybox code in my current project, but I can't take credit as most of it was lifted from a post to this very mailing list. Unfortunately, it's from the old list server and I can't seem to find the message in the current archives. The old link was: http://openscenegraph.org/archiver/osg-users/2005-June/0581.html osg::StateSet* stateset = new osg::StateSet; // Set texture mode to REPLACE osg::TexEnv* te = new osg::TexEnv; te->setMode(osg::TexEnv::REPLACE); stateset->setTextureAttributeAndModes(0, te, osg::StateAttribute::ON); // Turn off lighting and cull face stateset->setMode(GL_LIGHTING, osg::StateAttribute::OFF); stateset->setMode(GL_CULL_FACE, osg::StateAttribute::OFF); // Basic principle of skyboxes: render it last, and with a depth func // that only sets pixels at the far plane. That way, if the sky is not // visible at all for example, the sky won't be drawn (and possibly // fragment shaders will not be called) whereas rendering it first will // cause all pixels to be written, then overwritten by objects, and // possibly fragment shaders will have been called for nothing. // Clear the depth to the far plane. osg::Depth* depth = new osg::Depth(osg::Depth::LEQUAL, 1.0, 1.0); stateset->setAttributeAndModes(depth, osg::StateAttribute::ON); // Make pretty darn sure it is drawn last. stateset->setRenderBinDetails(1000, "RenderBin"); // Create a drawable for the skybox. osg::Geometry* drawable = new osg::Geometry; // Create vertices for box // [...] // Create texture coordinates for cubemaps // [...] // Create an index array for the box // [...] // Create a geode for the skybox osg::Geode* geode = new osg::Geode; geode->setName("Skybox"); // Disable culling geode->setCullingActive(false); // Set the stateset geode->setStateSet(stateset); // Add the skybox geode->addDrawable(drawable); // Next is setting the texture and the transform node... // [...] -- ______________________________________________________ Jean-Sebastien Guay [EMAIL PROTECTED] http://whitestar02.webhop.org/ ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
