[vlc-devel] [PATCH] opengl: prevent opengl calls from different threads

[Thomas Guillem]

FIne with me

On Tue, Sep 24, 2019, at 10:27, Alexandre Janniaux wrote:
> Most display controls, especially sizing ones, have been made synchronous,
> while an OpenGL context should be used in only one thread at a time and
> should not interfere with the context of the control calling thread.
> It is especially harmful when the calling context is using OpenGL, like
> in interfaces.

OK with the rational.

> ---
>  modules/video_output/opengl/display.c | 21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/modules/video_output/opengl/display.c 
> b/modules/video_output/opengl/display.c
> index 456304ebdf..8d4c73cb97 100644
> --- a/modules/video_output/opengl/display.c
> +++ b/modules/video_output/opengl/display.c
> @@ -73,6 +73,7 @@ struct vout_display_sys_t
>      vout_display_opengl_t *vgl;
>      vlc_gl_t *gl;
>      picture_pool_t *pool;
> +    vout_display_place_t place;
>  };
> 
>  /* Display callbacks */
> @@ -208,6 +209,10 @@ static void PictureDisplay (vout_display_t *vd, 
> picture_t *pic)
> 
>      if (vlc_gl_MakeCurrent (sys->gl) == VLC_SUCCESS)
>      {
> +        float window_ar = (float)sys->place.width / sys->place.height;
> +        vout_display_opengl_SetWindowAspectRatio(sys->vgl, window_ar);
> +        vout_display_opengl_Viewport(sys->vgl, sys->place.x, 
> sys->place.y,
> +                                     sys->place.width, 
> sys->place.height);

but, is it possible to call SetWindowAspectRatio() and Viewport() only if the place changed ?
Maybe the optimization is not worth it...

>          vout_display_opengl_Display (sys->vgl, &vd->source);
>          vlc_gl_ReleaseCurrent (sys->gl);
>      }
> @@ -230,7 +235,6 @@ static int Control (vout_display_t *vd, int query, 
> va_list ap)
>        {
>          vout_display_cfg_t c = *va_arg (ap, const vout_display_cfg_t 
> *);
>          const video_format_t *src = &vd->source;
> -        vout_display_place_t place;
> 
>          /* Reverse vertical alignment as the GL tex are Y inverted */
>          if (c.align.vertical == VLC_VIDEO_ALIGN_TOP)
> @@ -238,13 +242,8 @@ static int Control (vout_display_t *vd, int query, 
> va_list ap)
>          else if (c.align.vertical == VLC_VIDEO_ALIGN_BOTTOM)
>              c.align.vertical = VLC_VIDEO_ALIGN_TOP;
> 
> -        vout_display_PlacePicture(&place, src, &c);
> +        vout_display_PlacePicture(&sys->place, src, &c);
>          vlc_gl_Resize (sys->gl, c.display.width, c.display.height);
> -        if (vlc_gl_MakeCurrent (sys->gl) != VLC_SUCCESS)
> -            return VLC_SUCCESS;
> -        vout_display_opengl_SetWindowAspectRatio(sys->vgl, 
> (float)place.width / place.height);
> -        vout_display_opengl_Viewport(sys->vgl, place.x, place.y, 
> place.width, place.height);
> -        vlc_gl_ReleaseCurrent (sys->gl);
>          return VLC_SUCCESS;
>        }
> 
> @@ -252,14 +251,8 @@ static int Control (vout_display_t *vd, int query, 
> va_list ap)
>        case VOUT_DISPLAY_CHANGE_SOURCE_CROP:
>        {
>          const vout_display_cfg_t *cfg = va_arg (ap, const 
> vout_display_cfg_t *);
> -        vout_display_place_t place;
> 
> -        vout_display_PlacePicture(&place, &vd->source, cfg);
> -        if (vlc_gl_MakeCurrent (sys->gl) != VLC_SUCCESS)
> -            return VLC_SUCCESS;
> -        vout_display_opengl_SetWindowAspectRatio(sys->vgl, 
> (float)place.width / place.height);
> -        vout_display_opengl_Viewport(sys->vgl, place.x, place.y, 
> place.width, place.height);
> -        vlc_gl_ReleaseCurrent (sys->gl);
> +        vout_display_PlacePicture(&sys->place, &vd->source, cfg);
>          return VLC_SUCCESS;
>        }
>        case VOUT_DISPLAY_CHANGE_VIEWPOINT:
> --
> 2.23.0
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