Re: [osg-users] PBOs and stutterless texture uploading
Ulrich Hertlein wrote: Hi Eduard, On 28/09/10 6:08 , Eduard - Gabriel Munteanu wrote: I've been investigating an issue in Flightgear, an OSS flight sim using OSG. We have lots of stutter, usually in multiplayer, caused by loading new models (this happens whenever somebody join). Loading textures from disk happens on another thread (via DatabasePager), but I traced the issue to glTexImage2D() calls. So it's texture uploading to graphics driver / card that's causing it. It's not uncommon to see delays of 300ms for 500KiB - 1MiB textures. Did you try to enable object pre-compiling on the DatabasePager thread via 'DatabasePager::setDoPreCompile(true)'? /ulrich Thanks for your reply and sorry for the delay, I've been a bit busy. Yes, I tried setting precompiling on through both environment variables and code. It didn't help. :( Here's some more information. I'm using OSG from SVN revision 11785 (quite recent) on a Linux system, although other 2.9.x releases I tried exhibit the same problem. I use the latest Catalyst drivers for my graphics card. My hunch is somehow the card/driver doesn't like the pixel format in those textures and it's doing some internal conversions (e.g. RGB - RGBA). Geometry data doesn't seem to be a bottleneck here, and I'm not sure if precompiling helps at all. So if I could make use of PBOs, DMA and loading would happen asynchronously and the problem would go away. I don't mind if those parts of the scene graph get rendered 5-10 seconds later as long as it doesn't cause stutter. It would also remove any smaller stutters and improve framerate. On the other hand, I can't really go and fix up all textures in the data tree, even if there was a format that could improve the situation. Any thoughts on how to get this done? -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=32513#32513 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PBOs and stutterless texture uploading
Hi Eduard, The use of PBO may well help, but only if the pixel formats are accelerated properly by the driver, this can be a bit of lottery. It just so happens that my recent work on integrating GLU implementations directly into the core OSG has been prompted by the wish to pre-process imagery into a form that is better for downloading to the graphics card. I will be tweaking the gluScaleImage function to enable us to call it from any thread, rather being restricted to just threads with a valid graphics context, this opens the door to resizing, altering pixel formats and generating mipmaps all in normal CPU threads, such as parts threads that are loading data. Another step along this route I plan to integrate the NvidiaTextureTools SDK into a plugin to allow us to compress imagery to GL friendly compressed pixel formats, again this can be done as runtime pre-processing step so that all the data is a form that is ideal for downloading to the GPU and minimizing memory footprint and bandwidth. This will all be part of the next dev release, 2.9.10, and the up coming 3.0 release. Robert. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PBOs and stutterless texture uploading
Hi Eduard, On 28/09/10 6:08 , Eduard - Gabriel Munteanu wrote: I've been investigating an issue in Flightgear, an OSS flight sim using OSG. We have lots of stutter, usually in multiplayer, caused by loading new models (this happens whenever somebody join). Loading textures from disk happens on another thread (via DatabasePager), but I traced the issue to glTexImage2D() calls. So it's texture uploading to graphics driver / card that's causing it. It's not uncommon to see delays of 300ms for 500KiB - 1MiB textures. Did you try to enable object pre-compiling on the DatabasePager thread via 'DatabasePager::setDoPreCompile(true)'? /ulrich ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] PBOs and stutterless texture uploading
Hi, I've been investigating an issue in Flightgear, an OSS flight sim using OSG. We have lots of stutter, usually in multiplayer, caused by loading new models (this happens whenever somebody join). Loading textures from disk happens on another thread (via DatabasePager), but I traced the issue to glTexImage2D() calls. So it's texture uploading to graphics driver / card that's causing it. It's not uncommon to see delays of 300ms for 500KiB - 1MiB textures. The situation is quite bad. I'm using an ATI Radeon HD5850, and I generally get 30fps with maxed out shader/details settings in Flightgear and 8x-ish antialiasing added. But seconds-long stutter, under practically all combinations of settings, is unacceptable for a flight simulator. I'm not an OpenGL expert at all (quite the contrary), but it seems using PBOs might alleviate this issue by doing DMA instead of hogging the CPU for texture transfer. There's the other solution of compressing textures, but it's not a really viable option given what we have so far, and I'm unsure that's the right fix even if performance does seem to improve. We're using AC3D models, and the ac3d plugin loads both geometry and textures. However, I'm having difficulties setting up PBOs reliably. I attempted hacking the ac3d plugin and its TextureData class to hardcode PBO usage in the setTexture() method. Here are my attempts: 1) mImage-setPixelBufferObject(new osg::PixelBufferObject(mImage)); The PBO is set up, applyTexImage2D_load() finds it, but OSG crashes because GLBufferObject::getOffset() returns 0. 2) Creating another image object, setting up a PBO on it, cloning relevant properties from mImage, then doing copySubImage() from the previous mImage. I also tried doing Image::allocateImage() on it before copying. But either copySubImage() segfaults in GLU calls, or I hit the first problem again. 3) By some combination of luck and a typo I made in 2 above (reversing some coordinates) I got some textures showing up with wrong colors. It seems to be faster at first glance, but it still crashes at some point. What am I doing wrong? Indeed, hacking the plugin doesn't seem the best option, I was just doing that to test. I suppose, though I'm unsure if it's possible, I should iterate over the whole scene graph using the visitor pattern and set up PBOs for every texture. I'm a bit puzzled there's no simple way to just switch this on. What would you recommend? Any advice is appreciated. Thanks, Eduard -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=32112#32112 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
