Hi Lilith, It sounds like the lazy state updating in osg::State isn't functioning in this case, either a bug or an oversight.
Have you determined that this issue still occurs in svn/trunk? Robert. On Tue, Dec 22, 2009 at 12:54 AM, Lilith Bryant <[email protected]> wrote: > Hi Robert, and the list, > > I have found a performance issue with multitexturing. > > Once a state has had texture attributes applied for units >=1 > then excessive calls to glActiveTexture are made forever more. > > In particular, State::apply() and applyTextureMode() and > applyTextureAttribute() unconditionally change the active texture unit (with > setActiveTextureUnit), even if they cause no actual state change. > > The GL trace ends up littered with glActiveTexture calls: > > glActiveTexture(GL_TEXTURE0) > glBindTexture(GL_TEXTURE_2D,2) > glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_BORDER) > glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_BORDER) > glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR) > glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR) > glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAX_ANISOTROPY_EXT,1.000000) > glTexParameterfv(GL_TEXTURE_2D,GL_TEXTURE_BORDER_COLOR,0x4a8f8ac) > glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_COMPARE_MODE,GL_ZERO) > glActiveTexture(GL_TEXTURE1) > glActiveTexture(GL_TEXTURE2) > glActiveTexture(GL_TEXTURE3) > glCallList(4) > > All those glActiveTexture calls happen on every single call to State::apply() > > Note this is even after all the multitextured things are removed from the > scene. > > It occur because the textureModeMapList and textureAttributeMapList are > expanded, but never contracted. This itself isn't a problem, but the > unconditional changing of the active texture unit in State::apply() etc, JUST > IN CASE, is the problem. > > Back in v1.2 I implemented a fix for this, that I never got around to > submitting. Essentially it moves the call to setActiveTextureUnit from > State::apply etc down into the State::applyMode/applyAttribute/ > applyGlobalDefault functions. This allows those functions to decide at the > very last moment if the active texture unit really does need changing. > > This requires that applyMode/applyAttribute etc take an new optional TexUnit > parameter (with -1 meaning "DONT CARE WHICH", which is the value used for > normal attributes/modes ) . The alternative to a parameter is a member > variable in State, "requiredStateChangeTexUnit" or similar. > > This is clearly going to be quite an invasive patch to otherwise very old > code, so before I port my patch to the SVN head and submit it, I thought I'd > run it past you to see if: > > a) You'd be interested in receiving such a submission, and > b) If you had a preference as to using a parameter vs member variable for the > required tex unit. > > I have attached my changed v1.2 files for your reference. > > Regards, > Lilith > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
