vo_opengl: refactor into vo_gpu

This is done in several steps:

1. refactor MPGLContext -> struct ra_ctx
2. move GL-specific stuff in vo_opengl into opengl/context.c
3. generalize context creation to support other APIs, and add --gpu-api
4. rename all of the --opengl- options that are no longer opengl-specific
5. move all of the stuff from opengl/* that isn't GL-specific into gpu/
   (note: opengl/gl_utils.h became opengl/utils.h)
6. rename vo_opengl to vo_gpu
7. to handle window screenshots, the short-term approach was to just add
   it to ra_swchain_fns. Long term (and for vulkan) this has to be moved to
   ra itself (and vo_gpu altered to compensate), but this was a stop-gap
   measure to prevent this commit from getting too big
8. move ra->fns->flush to ra_gl_ctx instead
9. some other minor changes that I've probably already forgotten

Note: This is one half of a major refactor, the other half of which is
provided by rossy's following commit. This commit enables support for
all linux platforms, while his version enables support for all non-linux
platforms.

Note 2: vo_opengl_cb.c also re-uses ra_gl_ctx so it benefits from the
--opengl- options like --opengl-early-flush, --opengl-finish etc. Should
be a strict superset of the old functionality.

Disclaimer: Since I have no way of compiling mpv on all platforms, some
of these ports were done blindly. Specifically, the blind ports included
context_mali_fbdev.c and context_rpi.c. Since they're both based on
egl_helpers, the port should have gone smoothly without any major
changes required. But if somebody complains about a compile error on
those platforms (assuming anybody actually uses them), you know where to
complain.

1 files changed, 98 insertions, 0 deletions

diff --git a/video/out/gpu/user_shaders.h b/video/out/gpu/user_shaders.h
new file mode 100644
index 0000000000..94a070c8e2
--- /dev/null
+++ b/video/out/gpu/user_shaders.h
@@ -0,0 +1,98 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv 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.
+ *
+ * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MP_GL_USER_SHADERS_H
+#define MP_GL_USER_SHADERS_H
+
+#include "utils.h"
+#include "ra.h"
+
+#define SHADER_MAX_PASSES 32
+#define SHADER_MAX_HOOKS 16
+#define SHADER_MAX_BINDS 6
+#define SHADER_MAX_SAVED 64
+#define MAX_SZEXP_SIZE 32
+
+enum szexp_op {
+    SZEXP_OP_ADD,
+    SZEXP_OP_SUB,
+    SZEXP_OP_MUL,
+    SZEXP_OP_DIV,
+    SZEXP_OP_NOT,
+    SZEXP_OP_GT,
+    SZEXP_OP_LT,
+};
+
+enum szexp_tag {
+    SZEXP_END = 0, // End of an RPN expression
+    SZEXP_CONST, // Push a constant value onto the stack
+    SZEXP_VAR_W, // Get the width/height of a named texture (variable)
+    SZEXP_VAR_H,
+    SZEXP_OP2, // Pop two elements and push the result of a dyadic operation
+    SZEXP_OP1, // Pop one element and push the result of a monadic operation
+};
+
+struct szexp {
+    enum szexp_tag tag;
+    union {
+        float cval;
+        struct bstr varname;
+        enum szexp_op op;
+    } val;
+};
+
+struct compute_info {
+    bool active;
+    int block_w, block_h;     // Block size (each block corresponds to one WG)
+    int threads_w, threads_h; // How many threads form a working group
+    bool directly_writes;     // If true, shader is assumed to imageStore(out_image)
+};
+
+struct gl_user_shader_hook {
+    struct bstr pass_desc;
+    struct bstr hook_tex[SHADER_MAX_HOOKS];
+    struct bstr bind_tex[SHADER_MAX_BINDS];
+    struct bstr save_tex;
+    struct bstr pass_body;
+    struct gl_transform offset;
+    struct szexp width[MAX_SZEXP_SIZE];
+    struct szexp height[MAX_SZEXP_SIZE];
+    struct szexp cond[MAX_SZEXP_SIZE];
+    int components;
+    struct compute_info compute;
+};
+
+struct gl_user_shader_tex {
+    struct bstr name;
+    struct ra_tex_params params;
+    // for video.c
+    struct ra_tex *tex;
+};
+
+// Parse the next shader block from `body`. The callbacks are invoked on every
+// valid shader block parsed.
+void parse_user_shader(struct mp_log *log, struct ra *ra, struct bstr shader,
+                       void *priv,
+                       bool (*dohook)(void *p, struct gl_user_shader_hook hook),
+                       bool (*dotex)(void *p, struct gl_user_shader_tex tex));
+
+// Evaluate a szexp, given a lookup function for named textures
+bool eval_szexpr(struct mp_log *log, void *priv,
+                 bool (*lookup)(void *priv, struct bstr var, float size[2]),
+                 struct szexp expr[MAX_SZEXP_SIZE], float *result);
+
+#endif