> Is there a particular reason why using the example GLSL Vertex Shader (10.5 > Developer Examples), fps severely drops when attempting to shade objects that > are being rendered in a GL wireframe or GL Point mode (I've tested this with > stock Apple code as well as two common 3rd party plugins)? Is the processing > hit a bug or leak, or totally expected? Vertex shading seems especially > pricey in QC.
Line drawing isn't particularly well-optimized in gl these days (you can test rendering wireframes without vertex shading at all, and see a performance hit on even the newest of cards, despite touching very few pixels at all). Points typically aren't too slow, but they can have other quirks. Sometimes, mismatched modes (front faces are filled, back faces are wireframe, or the opposite) will incur an even bigger hit (perhaps because the GPU has to potentially switch modes for every triangle?) Vertex and Fragment shading in QC don't really do much massaging, and it's render-mode agnostic (it doesn't know or care if you're rendering points, lines, filled polys, etc), so there shouldn't be any performance inconsistencies there -- if you find a composition where that's not the case, I'd be interested to know about it (it's possible that vertex shading is taking place in software, which would of course provide a nice performance hit -- QC has no control over that). Make sure you're not running in Software GL mode, just in case ;) If it was a leak, it'd show up in Instruments and you'd eventually crash. When you say "vertex shading seems especially pricey in QC", what are you comparing it to? -- Christopher Wright [email protected] _______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com This email sent to [email protected]
