On Wed, Jun 06, 2012 at 06:42:44PM +0100, Michael Meeks wrote: > Hi guys, > > On Wed, 2012-06-06 at 16:33 +0100, Iain Billett wrote: > > I haven't experimented but I've heard that not using power-of-two > > lengths is seriously detrimental to performance. > > Must make a mental note to ask a GPU hacker; in fact - lets do that :-) > Luc - sorry to bother you with a quick question. For all these Android / > portable 3D chipsets that you deal with - is it really true that we need > to allocate power-of-two sized, preferably square textures ? [ we're > working on rendering documents to bitmaps to manipulate them for a > LibreOffice android viewer ]. > > > Considering we'll be using lots of resources to begin I think we > > should make every reasonable optimisation > > Sure; but say we have a Tablet, mine has 1280x800 resolution, are you > seriously suggesting rounding 1280 up to 2048 ? and 800 up to 1024 ? > giving a 2Mpixel texture instead of a 1Mpixel texture ;-) is that really > going to be more fast/efficient. Presumably having a sane rowstride (eg. > 1280) makes a ton of sense, but a power of two in each dimension ? > Anyhow - Luc can give an authoritative answer :-) > > > Also, in this arrangement, It would be nice to have the dimensions of > > the "document" area of the texture. Then if the rest of the bitmap is > > fully transparent and the plane is too we can render a "page" alone > > and keep track of dimensions. > > I guess. > > > My main concern with all this is in fact dealing with user interaction > > i.e. mapping measurements in pixels to OpenGL coordinates. This is > > more of a problem for editing, though. > > Yep. > > > Also, are we intending to have continuous scroll documents ( with all > > the pages available via scroll - like most desktop applications ) or > > would we be happy to have users flick (or otherwise) through pages. I > > think the latter would make it easier to manage resources for large > > documents. > > I think we'll want to flick through pages when we have them :-) For > spreadsheets of course we don't really have that (hence liking doubles > for positioning the view-pane incidentally). > > Thanks ! > > Michael.
Not sure whether it is so detrimental for performance, I guess it depends on the hw and driver implementation. And yes, it depends on the GL version whether non-power-of-two textures are accepted. For the record, i am not such a big 3D/GPU buff, most of my experience is with display stuff, some 2d accel/video/mpeg, and tons of lowlevel things. My actual GPU knowledge is mostly limited to what was shown at linuxtag a few weeks ago, where i was, once again, filling in the bottom end bits. My knowledge of openGL* is extremely limited, and this question is more for someone who has used GL on a variety of drivers and hardware, than for someone who fills in the bottom bits :) Luc Verhaegen. _______________________________________________ LibreOffice mailing list LibreOffice@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libreoffice
