[PATCH weston] libweston: don't accumulate damage from transparent views

[Pekka Paalanen]

On Wed, 18 Apr 2018 15:44:26 +0200
Emre Ucan <eucan at de.adit-jv.com> wrote:

> If view is set to be entirely transparent,
> there is no need to accumulate its damage.
> 
> This is an important optimization for
> using view transparency. Because otherwise
> transparent views are rendered like an
> opaque view, and their pixel values
> are set to 0 in fragment shader.
> 
> Signed-off-by: Emre Ucan <eucan at de.adit-jv.com>
> ---
>  libweston/compositor.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/libweston/compositor.c b/libweston/compositor.c
> index a9de4ac..4bcf120 100644
> --- a/libweston/compositor.c
> +++ b/libweston/compositor.c
> @@ -2122,7 +2122,10 @@ compositor_accumulate_damage(struct weston_compositor *ec)
>  		pixman_region32_init(&opaque);
>  
>  		wl_list_for_each(ev, &ec->view_list, link) {
> -			if (ev->plane != plane)
> +			/* If view is set to be entirely transparent,
> +			 * there is no need to accumulate its damage.
> +			 */
> +			if (ev->plane != plane || ev->alpha == 0.0f)
>  				continue;
>  
>  			view_accumulate_damage(ev, &opaque);

Hi,

why this instead of removing the whole view from the scenegraph?

You would also need to exclude the view in
weston_compositor_pick_view(), and adding these rendering special cases
around doesn't feel very good to me.


Thanks,
pq
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