Actually, you just made a very useful point re. regions - CI seems to glitch with 32bit colour + high resolution, tiling the image might help. It seems that if I use an image > 1024 pixels and run a CI Filter that samples at an offset, it can't sample to the right of the 1024pixel boundary for a destination to the left. I might have to implement some kind of tiling to get around that..
Sounds like a driver/CI bug -- I'd report it as concisely as possible, and then shake your fist at the sky in desperation when it doesn't get resolved ;) workarounds like what you describe are really annoying simply because when you do get it fixed, they'll fix it too, and then it'll break your fix. But of course, if you don't fix it, neither will they... so either way, be prepared to have a 1.1 ready to go on some 10.6.x update ;) (I've experienced this at least 3 times with 10.5)
Speaking of which, am I right in thinking thinking >8bit modes only work with POT textures? If so, tiling might help performance too.
From the GPU engineers I've spoken with (from both ATI and Nvidia), POT is an ancient relic that doesn't actually help performance significantly anymore. It can help with some fancy calls, like automatic mipmap generation, but other than that I don't think it'll help as much as you're hoping. I'm not sure on requiring POT for >8bpc modes -- I've never heard that, but I'm oft mistaken on intricate GL details. hardware-wise, POT+>8bpc only requires a different multiplier, so it's not like it actually requires any additional transistors or fanciness -- as long as the multiplier can handle a number 4x larger (2 extra bits), there's nothing physically required that isn't already there.
Anyway, I'm not fixated on NSImage or anything.. that's purely what the valueForOutputKey: method gives me by default. There's also valueForOutputKey: ofType:, so perhaps that will give me a convenient CGImage? CGImage is one of the image types available, but I don't know if I can specify the type I want or if it'll just tell me to reconsider my request :). I'll try it later.
I've not tried the ofType: variant, but I _think_ that lets you request CGImages. I'd give it a spin.
Oh: On leopard, requesting CGImages would give you BGRA images that claimed to be RGBA -- I don't think that was ever fixed on leopard, but maybe it's finally fixed since PPC is dead? you might want to check on that before jumping in headlong.
Btw, I'm using a published output port because I want the original data, not the 'resized to fit on screen' data that the QC snapshot methods will give me, so I suspect glReadPixels etc. won't quite cut it.
Yeah, readpixels is only good for contexts -- I was thinking you were having the QCRenderer render to the context, not act as an image filter. I always forget that kind of usage ;)
-- [ christopher wright ] [email protected] http://kineme.net/
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