Hi All, I'm currently working on multiple render target functionality, yesterday I checking in ColorMaski, BlendFunci and BlendEquationi, and today I've moved on to implementing glEnablei/glDisablei functionality. I'm torn of what naming convention to use and the granularity of the design - so I'd like feedback from the community about what feels sensible.
Originally I was thinking that as glEnable/glDisable functionality in imlemented via osg::StateSet::setMode(..) I'd add a StateSet::setModei() and expand similar support in osg::State. When I got into looking at how much code I'd need to duplicate+tweak to make this all work I decided that that much code for such a small chunk of functionality was totally disproportionate. When I come across issues like this I use this Complexity of implementation vs Functionality Ratio as an indication of how well designed something is. If it requires lots of Complexity for modest Functionality it screams out that it's the wrong approach. So I've taken a step back and am now thinking about other ways I could tackle this feature. My current favoured approach is to reuse the existing StateSet/StateAttribute mechanism and have one or more subclass from StateAttribute to wrap up the glEnablei and glDisablei functionality. If I am to follow the usual OpenGL->OSG naming convention it would seem sensible to have two classes osg::Enablei and osg::Disablei that wrap up glEnablei and glDisablei respectively. An alternative approach would be to create an osg::Modei class that has an Enabled/Disabled parameter. The Modei name would be a nod to the previous naming convention for handing glEnable/glDisable. The name Modes I originally adopted as the original OpenGL language around glEnable/glDisable used to label them as modes - this was all decided back in the late 90's. This during the fixed function pipeline era of OpenGL where you'd configure the OpenGL state machine by toggling different "modes". Since then a decade and half has passed and looking at modern docs for OpenGL the glEnable/glDisable and glEnablei/glDisablei now discuss OpenGL capability rather than modes. I guess the new naming sits better modern shader centric functionality. Given this perhaps if one is to have a single class then perhaps one should name it osg::Capability. The usage mode for the new class/classes would be something like: stateset->setAttribute(new osg::Enablei(GL_BLEND, 0)); stateset->setAttribubte(new osg::Disable(GL_SCISSOR_TEST,1)); OR stateset->setAttribute(new osg::Capabiltyi(GL_BLEND, 0, GL_TRUE)); stateset->setAttribute(new osg::Capabiltyi(GL_SCISSOR_TEST, 0, GL_FALSE); It might still be better though for me to bite the bullet and do the hard work refatoring the internals of osg::State/osg::StateSet to handle a new osg::StateSet::setModei(..) method and associated set/gets. Thoughts/Opinions/Suggestions? Robert.
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