Will I need to do anything in osg to make sure it uses the pre-generated mipmaps stored in the DDS file and not recreate new ones? Working on saving the textures out as dds now.
-----Original Message----- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Sergey Polischuk Sent: Monday, August 27, 2012 2:23 AM To: OpenSceneGraph Users Subject: Re: [osg-users] Texture Questions Hi You can use compressed textures in dds format, as they support dxtc texture compression. You can create those with ati compressonator tool, nvidia texture tools, or in photoshop using nvidia plugin. For rgb images you'll get 6x compression ratio. Also, you can save textures in dds format with pre-generated mipmaps, if you need those. Cheers. 24.08.2012, 21:13, "Cary, Karl A." <karl.a.c...@saic.com>: > I do have the ability to pre-process. The question is, what file > formats support openGL compression and how do I take them from jpeg to > these formats? As for mipmapping, you mentioned that it can be done CPU side. > How do I initiate this? Since the texture load is happening in a > separate thread, I can afford CPU time to do this rather than pushing > more on to the GPU. I can test out to see if it is worthwhile. > > -----Original Message----- > From: osg-users-boun...@lists.openscenegraph.org > [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of > Robert Osfield > Sent: Friday, August 24, 2012 11:40 AM > To: OpenSceneGraph Users > Subject: Re: [osg-users] Texture Questions > > Hi Karl, > > On 24 August 2012 14:40, Cary, Karl A. <karl.a.c...@saic.com> wrote: > >> I have an application that loads several 2048x2048 textures in a >> separate thread before passing off to the main to be applied to the >> geometry. I am trying to do anything and everything I can to improve >> performance on them as the number of textures will increase from >> several to quite a lot. So I am looking at every option I can and >> have >> run in to several questions that I was hoping to get some advice on. >> I >> am creating osg::Texture2D and loading them with an osg::Image read >> in > > from a jpg file. > > Excatly how many textures are you talking about? > > Will of the texture reside in memory and be rendered at the same time? > > Do you have an flexibility w.r.t pre-processing the image data into > other file formats? > > What pixel format do the textures have? RGB? > >> 1) Is mipmapping enabled by default? Or do I need to call >> allocateMipmapLevels? > > By default the osg::Texture* will use trilinear mipmapping, if the > osg::Image doesn't contain the mipmaps then it'll either generate them > on demand in the rendering thread either done by the GL driver or GPU > using OpenGL extensions for generating mipmaps, or on the CPU using > GLU functions when the driver doesn't support the generate mipmap > extensions. > > You can switch the mipmapping off by just setting the > texture->setFilter(Texture::MIN_FILTER, Texture::LINEAR); > >> 2) If it is enabled, how many levels are created by default? > > osg::Texture* will automatically work out how many levels are required > based on the dimensions of the texture. > >> 3) Would changing the internal format mode to one of the > > compression > >> formats actually perform the compression or does that need to be >> done >> manually? > > If the source imagery is not in an OpenGL compressed format then the > driver will do the compression for you, however this is an expensive > operation so generally not one you'd during rendering, rather OpenGL > compression is something you'd want to do in pre-processing step. > >> 4) If I do need to do the compression, how can I do it without > > applying > >> it to geometry in my separate thread? I have only seen it done via >> the >> CompressTexturesVisitor applied to a node (as in osgconv), would I >> have to make some empty node and apply the texture to it to do this? > > To compress in a background thread you can use the OSG's now support > for compressing textures using NVTT (there is plugin for this when you > compile the OSG when the NVTT SDK is available). You'll need OSG-3.x > for this. > >> 5) Is there any way to send a texture down to the graphics card > > prior > >> to applying it to geometry? > > You can pre-compile objects using the IncrementalCompileOperator, > however, this is still done as part of the rendering thread so > depending upon your requirements might not make a difference. > >> 6) Any other efficiency things I should be looking at? > > Pre-processing data so that it's pre-mipmapped and using OpenGL > compressed texture is the best way if you want to maximize performance > throughput of textures as this reduces how much work the CPU and GPU > need to do to download and use the data. OpenGL compression is less > aggressive than compression supported by conventional image formats so > the files on disk will be bigger. > > Robert. > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph. > or > g > _______________________________________________ > 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 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
