Hi, I have the same questions. Using float, It's easier to map to OGLES2, Decrease memory usage and accelerated using ARM SIMD. if you do profiling for CSS transformation/Animation, you'll find TransformationMatrix hotspots that should be well optimized using NEON.
-Kuii On Mon, May 21, 2012 at 6:55 PM, Stephen Chenney <[email protected]> wrote: > Ideally WebKit would avoid casts by consistently using either double or > floats everywhere a floating point representation is needed. I don't think > it's as simple as adding a typedef, but maybe it is. In any event it would > have to be spelled out in the style guide. > > My gut feeling is that floats are enough for web layout, and map better onto > GPU back ends where bandwidth (memory) really matters. Is there anything in > the specs that force one or the other, or both? Is there a compelling web > content scenario that demands double precision? > > Stephen. > > > On Mon, May 21, 2012 at 1:37 PM, Ryosuke Niwa <[email protected]> wrote: >> >> Maybe you can add a typedef in Platform.h to make it configurable? e.g. >> maybe you want to be able to use long double instead of regular double in >> the future. >> >> - Ryosuke >> >> On Mon, May 21, 2012 at 10:34 AM, Simon Fraser <[email protected]> >> wrote: >>> >>> TransformationMatrix started out as floats, then got changed to doubles >>> in <http://trac.webkit.org/changeset/40761> >>> >>> This was done because on most hardware there is no penalty for using >>> doubles over floats, and provided a better match with our system APIs that >>> used doubles. >>> >>> I'd prefer to take a forward-looking stance here, and assume that in time >>> hardware will catch up. >>> >>> Simon >>> >>> On May 21, 2012, at 4:04 AM, Zoltan Herczeg wrote: >>> >>> > Hi, >>> > >>> > is there any reason why the transformations in WebKit use doubles? We >>> > could optimize some functions further with ARM SIMD if they would be >>> > floats. Is there any objection to make them float if the change would >>> > have >>> > no other side effects except some rounding because of the lower >>> > precision? >>> > >>> > Regards, >>> > Zoltan >>> > >>> > >>> > _______________________________________________ >>> > webkit-dev mailing list >>> > [email protected] >>> > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev >>> >>> _______________________________________________ >>> webkit-dev mailing list >>> [email protected] >>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev >> >> >> >> _______________________________________________ >> webkit-dev mailing list >> [email protected] >> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev >> > > > _______________________________________________ > webkit-dev mailing list > [email protected] > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev > _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
