vo_opengl: remove pre/post/scale-shaders

Deprecated in favor of user-shaders, which are functionally equivalent
but superior. (Except in the case of scaler-shader, which has no direct
replacement, but it turned out to be a very unpopular feature either way
- most custom scalers don't fit into the mpv kernel infrastructure and
are therefore implemented as user shaders either way)

Signed-off-by: wm4 <wm4@nowhere>

4 files changed, 20 insertions, 133 deletions

diff --git a/DOCS/interface-changes.rst b/DOCS/interface-changes.rst
index 9bfbdcf3b0..f2b8b19514 100644
--- a/DOCS/interface-changes.rst
+++ b/DOCS/interface-changes.rst
@@ -35,6 +35,8 @@ Interface changes
         - "idle" -> "idle-active"
       the old names are deprecated
     - remove deprecated "hwdec-active" and "hwdec-detected" properties
+    - remove "pre-shaders", "post-shaders" and "scale-shader": deprecated
+      in favor of "user-shaders"
  --- mpv 0.20.0 ---
     - add --image-display-duration option - this also means that image duration
       is not influenced by --mf-fps anymore in the general case (this is an
diff --git a/DOCS/man/vo.rst b/DOCS/man/vo.rst
index dda3ea61cd..2c7b995843 100644
--- a/DOCS/man/vo.rst
+++ b/DOCS/man/vo.rst
@@ -584,68 +584,9 @@ Available video output drivers are:
         better than without it) since it will extend the size to match only the
         milder of the scale factors between the axes.
 
-    ``pre-shaders=<files>``, ``post-shaders=<files>``, ``scale-shader=<file>``
-        Custom GLSL fragment shaders.
-
-        pre-shaders (list)
-            These get applied after conversion to RGB and before linearization
-            and upscaling. Operates on non-linear RGB (same as input). This is
-            the best place to put things like sharpen filters.
-        scale-shader
-            This gets used instead of scale/cscale when those options are set
-            to ``custom``. The colorspace it operates on depends on the values
-            of ``linear-scaling`` and ``sigmoid-upscaling``, so no assumptions
-            should be made here.
-        post-shaders (list)
-            These get applied after upscaling and subtitle blending (when
-            ``blend-subtitles`` is enabled), but before color management.
-            Operates on linear RGB if ``linear-scaling`` is in effect,
-            otherwise non-linear RGB. This is the best place for colorspace
-            transformations (eg. saturation mapping).
-
-        These files must define a function with the following signature::
-
-            vec4 sample_pixel(sampler2D tex, vec2 pos, vec2 tex_size)
-
-        (If there is no string ``sample_pixel`` in the shader script, it will
-        use ``sample`` instead. This is a compatibility hack for older shader
-        scripts, and is deprecated.)
-
-        The meanings of the parameters are as follows:
-
-        sampler2D tex
-            The source texture for the shader.
-        vec2 pos
-            The position to be sampled, in coordinate space [0-1].
-        vec2 tex_size
-            The size of the texture, in pixels. This may differ from image_size,
-            eg. for subsampled content or for post-shaders.
-
-        In addition to these parameters, the following uniforms are also
-        globally available:
-
-        float random
-            A random number in the range [0-1], different per frame.
-        int frame
-            A simple count of frames rendered, increases by one per frame and
-            never resets (regardless of seeks).
-        vec2 image_size
-            The size in pixels of the input image.
-        vec2 target_size
-            The size in pixels of the visible part of the scaled (and possibly
-            cropped) image.
-
-        For example, a shader that inverts the colors could look like this::
-
-            vec4 sample(sampler2D tex, vec2 pos, vec2 tex_size)
-            {
-                vec4 color = texture(tex, pos);
-                return vec4(1.0 - color.rgb, color.a);
-            }
-
     ``user-shaders=<files>``
-        Custom GLSL hooks. These are similar to ``post-shaders`` etc., but more
-        flexible: They can be injected at almost arbitrary points in the
+        Custom GLSL hooks. These are a flexible way to add custom fragment
+        shaders, which can be injected at almost arbitrary points in the
         rendering pipeline, and access all previous intermediate textures.
 
         .. admonition:: Warning
@@ -738,8 +679,19 @@ Available video output drivers are:
             The raw bound texture itself. The use of this should be
             avoided unless absolutely necessary.
 
-        In addition, the global uniforms described in ``post-shaders`` are
-        also available.
+        In addition to these parameters, the following uniforms are also
+        globally available:
+
+        float random
+            A random number in the range [0-1], different per frame.
+        int frame
+            A simple count of frames rendered, increases by one per frame and
+            never resets (regardless of seeks).
+        vec2 image_size
+            The size in pixels of the input image.
+        vec2 target_size
+            The size in pixels of the visible part of the scaled (and possibly
+            cropped) image.
 
         Internally, vo_opengl may generate any number of the following
         textures. Whenever a texture is rendered and saved by vo_opengl, all of
diff --git a/video/out/opengl/video.c b/video/out/opengl/video.c
index 8e419a1bd5..658153372e 100644
--- a/video/out/opengl/video.c
+++ b/video/out/opengl/video.c
@@ -54,7 +54,6 @@ static const char *const fixed_scale_filters[] = {
     "bilinear",
     "bicubic_fast",
     "oversample",
-    "custom",
     NULL
 };
 static const char *const fixed_tscale_filters[] = {
@@ -268,7 +267,6 @@ struct gl_video {
     bool hwdec_active;
 
     bool dsi_warned;
-    bool custom_shader_fn_warned;
     bool broken_frame; // temporary error state
 };
 
@@ -436,9 +434,6 @@ const struct m_sub_options gl_video_conf = {
                    ({"no", BLEND_SUBS_NO},
                     {"yes", BLEND_SUBS_YES},
                     {"video", BLEND_SUBS_VIDEO})),
-        OPT_STRING("scale-shader", scale_shader, 0),
-        OPT_STRINGLIST("pre-shaders", pre_shaders, 0),
-        OPT_STRINGLIST("post-shaders", post_shaders, 0),
         OPT_STRINGLIST("user-shaders", user_shaders, 0),
         OPT_FLAG("deband", deband, 0),
         OPT_SUBSTRUCT("deband", deband_opts, deband_conf, 0),
@@ -452,6 +447,9 @@ const struct m_sub_options gl_video_conf = {
         OPT_REMOVED("srgb", "use target-prim=bt709:target-trc=srgb instead"),
         OPT_REMOVED("source-shader", "use :deband to enable debanding"),
         OPT_REMOVED("prescale-luma", "use user shaders for prescaling"),
+        OPT_REMOVED("scale-shader", "use user-shaders instead"),
+        OPT_REMOVED("pre-shaders", "use user-shaders instead"),
+        OPT_REMOVED("post-shaders", "use user-shaders instead"),
 
         OPT_REPLACED("lscale", "scale"),
         OPT_REPLACED("lscale-down", "scale-down"),
@@ -1250,19 +1248,6 @@ static void load_shader(struct gl_video *p, struct bstr body)
                                    p->dst_rect.y1 - p->dst_rect.y0});
 }
 
-static const char *get_custom_shader_fn(struct gl_video *p, const char *body)
-{
-    if (!p->gl->es && strstr(body, "sample") && !strstr(body, "sample_pixel")) {
-        if (!p->custom_shader_fn_warned) {
-            MP_WARN(p, "sample() is deprecated in custom shaders. "
-                       "Use sample_pixel()\n");
-            p->custom_shader_fn_warned = true;
-        }
-        return "sample";
-    }
-    return "sample_pixel";
-}
-
 // Semantic equality
 static bool double_seq(double a, double b)
 {
@@ -1455,16 +1440,6 @@ static void pass_sample(struct gl_video *p, struct img_tex tex,
         pass_sample_bicubic_fast(p->sc);
     } else if (strcmp(name, "oversample") == 0) {
         pass_sample_oversample(p->sc, scaler, w, h);
-    } else if (strcmp(name, "custom") == 0) {
-        struct bstr body = load_cached_file(p, p->opts.scale_shader);
-        if (body.start) {
-            load_shader(p, body);
-            const char *fn_name = get_custom_shader_fn(p, body.start);
-            GLSLF("// custom scale-shader\n");
-            GLSLF("color = %s(tex, pos, size);\n", fn_name);
-        } else {
-            p->opts.scale_shader = NULL;
-        }
     } else if (scaler->kernel && scaler->kernel->polar) {
         pass_sample_polar(p->sc, scaler);
     } else if (scaler->kernel) {
@@ -1538,19 +1513,6 @@ static void unsharp_hook(struct gl_video *p, struct img_tex tex,
     pass_sample_unsharp(p->sc, p->opts.unsharp);
 }
 
-static void user_hook_old(struct gl_video *p, struct img_tex tex,
-                          struct gl_transform *trans, void *priv)
-{
-    const char *body = priv;
-    assert(body);
-
-    GLSLHF("#define pixel_size HOOKED_pt\n");
-    load_shader(p, bstr0(body));
-    const char *fn_name = get_custom_shader_fn(p, body);
-    GLSLF("// custom shader\n");
-    GLSLF("color = %s(HOOKED_raw, HOOKED_pos, HOOKED_size);\n", fn_name);
-}
-
 struct szexp_ctx {
     struct gl_video *p;
     struct img_tex tex;
@@ -1627,26 +1589,6 @@ static void user_hook_free(struct tex_hook *hook)
     talloc_free(hook->priv);
 }
 
-static void pass_hook_user_shaders_old(struct gl_video *p, char *name,
-                                       char **shaders)
-{
-    assert(name);
-    if (!shaders)
-        return;
-
-    for (int n = 0; shaders[n] != NULL; n++) {
-        char *body = load_cached_file(p, shaders[n]).start;
-        if (body) {
-            pass_add_hook(p, (struct tex_hook) {
-                .hook_tex = name,
-                .bind_tex = {"HOOKED"},
-                .hook = user_hook_old,
-                .priv = body,
-            });
-        }
-    }
-}
-
 static void pass_hook_user_shaders(struct gl_video *p, char **shaders)
 {
     if (!shaders)
@@ -1698,8 +1640,6 @@ static void gl_video_setup_hooks(struct gl_video *p)
         });
     }
 
-    pass_hook_user_shaders_old(p, "MAIN", p->opts.pre_shaders);
-    pass_hook_user_shaders_old(p, "SCALED", p->opts.post_shaders);
     pass_hook_user_shaders(p, p->opts.user_shaders);
 }
 
@@ -2988,10 +2928,6 @@ static bool check_dumb_mode(struct gl_video *p)
                 return false;
         }
     }
-    if (o->pre_shaders && o->pre_shaders[0])
-        return false;
-    if (o->post_shaders && o->post_shaders[0])
-        return false;
     if (o->user_shaders && o->user_shaders[0])
         return false;
     if (p->use_lut_3d)
diff --git a/video/out/opengl/video.h b/video/out/opengl/video.h
index 140a4682c8..29300c3312 100644
--- a/video/out/opengl/video.h
+++ b/video/out/opengl/video.h
@@ -130,9 +130,6 @@ struct gl_video_opts {
     int interpolation;
     float interpolation_threshold;
     int blend_subs;
-    char *scale_shader;
-    char **pre_shaders;
-    char **post_shaders;
     char **user_shaders;
     int deband;
     struct deband_opts *deband_opts;