[vlc-devel] [PATCH 01/27] opengl: introduce OpenGL filter API
Romain Vimont
rom1v at videolabs.io
Fri Jun 26 17:22:20 CEST 2020
On Fri, Jun 26, 2020 at 10:58:40AM +0200, Alexandre Janniaux wrote:
> Hi,
>
> IMHO, there is no point in mentionning that you extract a
> superclass if in the end, you extract a specific field.
I wanted to say that semantically, this commit extracts an
"interface"/"super-class" containing what is specific to a filter. And
that the renderer now "extends"/"implements" it (it is a specific
filter).
(We could also say that the filter trait is implemented for the
renderer.) ;)
> A superclass would probably be a direct pointer cast like
>
> > + struct vlc_gl_filter *renderer_filter = (strcut vlc_gl_filter*)vgl->renderer;
It's just an implementation/code-style detail. We could move the filter
field so that it becomes the first, and cast as you say (but I prefer to
use the field explicitly for type-checking).
However, I agree that it may be better to avoid concepts from other
languages. I suggest to simplify as follow:
Expose a filter API, and make renderer a specific filter.
What do you think?
>
> Regards,
> --
> Alexandre Janniaux
> Videolabs
>
> On Thu, Jun 25, 2020 at 02:22:48PM +0200, Romain Vimont wrote:
> > Extract a "super-class" filter from renderer. A renderer is now a
> > specific filter.
> >
> > Co-authored-by: Alexandre Janniaux <ajanni at videolabs.io>
> > ---
> > modules/video_output/opengl/Makefile.am | 1 +
> > modules/video_output/opengl/filter.h | 42 +++++++++++++++++++++++
> > modules/video_output/opengl/renderer.c | 16 +++++++--
> > modules/video_output/opengl/renderer.h | 12 +++----
> > modules/video_output/opengl/vout_helper.c | 4 ++-
> > 5 files changed, 64 insertions(+), 11 deletions(-)
> > create mode 100644 modules/video_output/opengl/filter.h
> >
> > diff --git a/modules/video_output/opengl/Makefile.am b/modules/video_output/opengl/Makefile.am
> > index 58acc824fc..3be82c458c 100644
> > --- a/modules/video_output/opengl/Makefile.am
> > +++ b/modules/video_output/opengl/Makefile.am
> > @@ -1,4 +1,5 @@
> > OPENGL_COMMONSOURCES = video_output/opengl/vout_helper.c \
> > + video_output/opengl/filter.h \
> > video_output/opengl/gl_api.c \
> > video_output/opengl/gl_api.h \
> > video_output/opengl/gl_common.h \
> > diff --git a/modules/video_output/opengl/filter.h b/modules/video_output/opengl/filter.h
> > new file mode 100644
> > index 0000000000..f4b3f8bbf2
> > --- /dev/null
> > +++ b/modules/video_output/opengl/filter.h
> > @@ -0,0 +1,42 @@
> > +/*****************************************************************************
> > + * filter.h
> > + *****************************************************************************
> > + * Copyright (C) 2020 VLC authors and VideoLAN
> > + * Copyright (C) 2020 Videolabs
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms of the GNU Lesser General Public License as published by
> > + * the Free Software Foundation; either version 2.1 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public License
> > + * along with this program; if not, write to the Free Software Foundation,
> > + * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
> > + *****************************************************************************/
> > +
> > +#ifndef VLC_GL_FILTER_H
> > +#define VLC_GL_FILTER_H
> > +
> > +struct vlc_gl_filter;
> > +
> > +struct vlc_gl_filter_ops {
> > + /**
> > + * Draw the result of the filter to the current framebuffer
> > + */
> > + int (*draw)(struct vlc_gl_filter *filter);
> > +};
> > +
> > +/**
> > + * OpenGL filter, in charge of a rendering pass.
> > + */
> > +struct vlc_gl_filter {
> > + const struct vlc_gl_filter_ops *ops;
> > + void *sys;
> > +};
> > +
> > +#endif
> > diff --git a/modules/video_output/opengl/renderer.c b/modules/video_output/opengl/renderer.c
> > index aa51f8b3a3..590fc3e46c 100644
> > --- a/modules/video_output/opengl/renderer.c
> > +++ b/modules/video_output/opengl/renderer.c
> > @@ -37,6 +37,7 @@
> > #include <vlc_es.h>
> > #include <vlc_picture.h>
> >
> > +#include "filter.h"
> > #include "gl_util.h"
> > #include "internal.h"
> > #include "vout_helper.h"
> > @@ -321,6 +322,9 @@ vlc_gl_renderer_Delete(struct vlc_gl_renderer *renderer)
> >
> > static int SetupCoords(struct vlc_gl_renderer *renderer);
> >
> > +static int
> > +Draw(struct vlc_gl_filter *filter);
> > +
> > struct vlc_gl_renderer *
> > vlc_gl_renderer_New(vlc_gl_t *gl, const struct vlc_gl_api *api,
> > struct vlc_gl_sampler *sampler)
> > @@ -332,6 +336,12 @@ vlc_gl_renderer_New(vlc_gl_t *gl, const struct vlc_gl_api *api,
> > if (!renderer)
> > return NULL;
> >
> > + static const struct vlc_gl_filter_ops filter_ops = {
> > + .draw = Draw,
> > + };
> > + renderer->filter.ops = &filter_ops;
> > + renderer->filter.sys = renderer;
> > +
> > renderer->sampler = sampler;
> >
> > renderer->gl = gl;
> > @@ -735,9 +745,11 @@ static int SetupCoords(struct vlc_gl_renderer *renderer)
> > return VLC_SUCCESS;
> > }
> >
> > -int
> > -vlc_gl_renderer_Draw(struct vlc_gl_renderer *renderer)
> > +static int
> > +Draw(struct vlc_gl_filter *filter)
> > {
> > + struct vlc_gl_renderer *renderer = filter->sys;
> > +
> > const opengl_vtable_t *vt = renderer->vt;
> >
> > vt->Clear(GL_COLOR_BUFFER_BIT);
> > diff --git a/modules/video_output/opengl/renderer.h b/modules/video_output/opengl/renderer.h
> > index 7130cfb262..9aec83d2e2 100644
> > --- a/modules/video_output/opengl/renderer.h
> > +++ b/modules/video_output/opengl/renderer.h
> > @@ -26,6 +26,7 @@
> > #include <vlc_opengl.h>
> > #include <vlc_plugin.h>
> >
> > +#include "filter.h"
> > #include "gl_api.h"
> > #include "gl_common.h"
> > #include "interop.h"
> > @@ -47,6 +48,9 @@ struct vlc_gl_renderer
> > const struct vlc_gl_api *api;
> > const opengl_vtable_t *vt; /* for convenience, same as &api->vt */
> >
> > + /* vlc_gl_renderer "extends" vlc_gl_filter */
> > + struct vlc_gl_filter filter;
> > +
> > /* True to dump shaders */
> > bool dump_shaders;
> >
> > @@ -108,14 +112,6 @@ vlc_gl_renderer_New(vlc_gl_t *gl, const struct vlc_gl_api *api,
> > void
> > vlc_gl_renderer_Delete(struct vlc_gl_renderer *renderer);
> >
> > -/**
> > - * Draw the prepared picture
> > - *
> > - * \param sr the renderer
> > - */
> > -int
> > -vlc_gl_renderer_Draw(struct vlc_gl_renderer *renderer);
> > -
> > int
> > vlc_gl_renderer_SetViewpoint(struct vlc_gl_renderer *renderer,
> > const vlc_viewpoint_t *p_vp);
> > diff --git a/modules/video_output/opengl/vout_helper.c b/modules/video_output/opengl/vout_helper.c
> > index b6105dd062..993bb405f1 100644
> > --- a/modules/video_output/opengl/vout_helper.c
> > +++ b/modules/video_output/opengl/vout_helper.c
> > @@ -267,7 +267,9 @@ int vout_display_opengl_Display(vout_display_opengl_t *vgl)
> > OpenGL providers can call vout_display_opengl_Display to force redraw.
> > Currently, the OS X provider uses it to get a smooth window resizing */
> >
> > - int ret = vlc_gl_renderer_Draw(vgl->renderer);
> > + /* Retrieve the "super-class" (renderer "extends" filter) */
> > + struct vlc_gl_filter *renderer_filter = &vgl->renderer->filter;
> > + int ret = renderer_filter->ops->draw(renderer_filter);
> > if (ret != VLC_SUCCESS)
> > return ret;
> >
> > --
> > 2.27.0
> >
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