Hi Guy,
>From what I’ve seen osgWidget would be an overkill for us, while not >implementing the features we do need. In any case, I’ve quickly looked into osgWidget source code, and it seems it’s using a single transparent bin with z ordering (WindowManager.cpp, around line 400, assigns different z values to windows when changing the focus of a window). This is currently what we are doing, but I’ve found it very error prone in our case. Cheers, Tanguy From: [email protected] [mailto:[email protected]] On Behalf Of Guy Sent: Thursday 02 April 2009 12:28 To: OpenSceneGraph Users Subject: Re: [osg-users] Controlling the rendering order Maybe you should look at osgWidget which handles GUI elements. Guy. ________________________________ מאת: [email protected] [mailto:[email protected]] בשם Tanguy Fautre נשלח: Thursday, April 02, 2009 2:27 PM אל: OpenSceneGraph Users נושא: Re: [osg-users] Controlling the rendering order Hi Robert, Do you suggest I create an additional bin type (e.g. GUI_ELEMENT_BIN) in addition to OPAQUE_BIN and TRANSPARENT_BIN, and write my own sort algorithm for those (i.e. render in the same order children appears in) ? Would it be relatively easy to do so? The thing is I’m quite happy with the way OSG sorts nodes most of the time, but for GUI elements (at least in our case) there is no performance benefit to do so. Almost everything use the same states (blending on, no depth test/write, no lighting) while only the texture changes. Cheers, Tanguy From: [email protected] [mailto:[email protected]] On Behalf Of Robert Osfield Sent: Thursday 02 April 2009 11:59 To: OpenSceneGraph Users Subject: Re: [osg-users] Controlling the rendering order Hi Tanguy, The OSG sorts the objects in opaque bin to minimize state changes, this is crucial for performance - it's a pretty fundamental part to efficient rendering and standard practice in high performance graphics toolkts.. This does mean the ordering changes. You have complete control over the bins though, you can change the sort algorithm on them, you can create own bins, set the overall render order. Within a single geometry the order is drawn in the order that the primitives are placed in the geometry, so perhaps this is sufficient for your purposes. Robert. On Thu, Apr 2, 2009 at 11:02 AM, Tanguy Fautre <[email protected]> wrote: Hi, When doing GUI elements in OpenGL, it's particularly useful to exactly control the rendering order. Usually, this goes like this: glDepthMask(0); glDisable(GL_DEPTH_TEST); glDisable(GL_LIGHTING); glEnable(GL_BLEND); /* Render GUI back to front */ /* Note that we use Z = 0.0 all the time */ glBegin(GL_QUADS); glVertex2f(x, y); /* ... */ It's very easy to do directly in OpenGL, but with OSG I've currently found it ridiculously hard. The reason is that OSG change to rendering order to optimize things (which is good in most cases, except this one). Is there any way to easily control the rendering order of nodes in OSG (e.g. set a node property to tell OSG to render children nodes in order)? I've found render bins to be over complicated to solve this (also they require the user to assign a unique and ordered id to each of them), and assigning a Z value to each GUI element is also tedious and error prone. Am I missing something? Cheers, Tanguy _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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