On 10/02/2014 12:37 AM, Pekka Paalanen wrote:
On Wed, 1 Oct 2014 18:09:32 -0700 Jason Ekstrand <ja...@jlekstrand.net> wrote:
(do we use "bool" in weston? Maybe just return int). We may need both x and y scales and it may be useful to get those as floats. I'm not sure on that. Pekka, what would the RPi backend use?
It looks like most of the code uses <stdbool.h>, "bool", and "true" and "false". However I also found a lot of instances of TRUE, FALSE, EGL_TRUE, EGL_FALSE, and using integer and 1 and 0 as return values.
Futhermore, if you wanted to cache the buffer-to-output matrix, you would end up with number_of_views * number_of_outputs matrices to be cached. The buffer-to-global per-view matrix might not change too often, but we tend to paint outputs in turns, which means doing just per-view cached total matrix is a waste. So you might have buffer-to-surface matrix in weston_surface, then buffer-to-global matrix cached in weston_view. I'm not sure it makes sense to cache buffer-to-output anywhere.
Actually most backends are going to analyze the matrix anyway, so using this to short-circuit filtering is not that useful.
But a set of flags attached to the matrix can help in speeding up multiplication. This would avoid having to cache all the matrices and would make creating them faster in normal cases. The flags should be designed so when you multiply the matrix you can bitwise and the flags. Something like this:
AFFINE: last row is 0,0,?,1 NO_SKEW: a00*a01+a10*a11 ~= 0 NO_SCALE: a00^2+a01^2 ~= 1 && a10^2+a11^2 ~= 1 ORTHO: a00==a11==0 or a01==a10==0 NO_ROTATE: a01==a10==0 NOT_DEGENERATE: a00*a11-a10*a01 != 0 NO_MIRROR: a00,a01,a10,a11 are all >= 0 INT_SCALE: a00,a01,a10,a11 are all integers INT_TRANSLATE: a03 and a13 are integers IDENTITY: identity matrix _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel
