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diff --git a/libmpv/render_gl.h b/libmpv/render_gl.h
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+/* Copyright (C) 2018 the mpv developers
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef MPV_CLIENT_API_RENDER_GL_H_
+#define MPV_CLIENT_API_RENDER_GL_H_
+
+#include "render.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * OpenGL backend
+ * --------------
+ *
+ * This header contains definitions for using OpenGL with the render.h API.
+ *
+ * OpenGL interop
+ * --------------
+ *
+ * The OpenGL backend has some special rules, because OpenGL itself uses
+ * implicit per-thread contexts, which causes additional API problems.
+ *
+ * This assumes the OpenGL context lives on a certain thread controlled by the
+ * API user. All mpv_render_* APIs have to be assumed to implicitly use the
+ * OpenGL context if you pass a mpv_render_context using the OpenGL backend,
+ * unless specified otherwise.
+ *
+ * The OpenGL context is indirectly accessed through the OpenGL function
+ * pointers returned by the get_proc_address callback in mpv_opengl_init_params.
+ * Generally, mpv will not load the system OpenGL library when using this API.
+ *
+ * OpenGL state
+ * ------------
+ *
+ * OpenGL has a large amount of implicit state. All the mpv functions mentioned
+ * above expect that the OpenGL state is reasonably set to OpenGL standard
+ * defaults. Likewise, mpv will attempt to leave the OpenGL context with
+ * standard defaults. The following state is excluded from this:
+ *
+ *      - the glViewport state
+ *      - the glScissor state (but GL_SCISSOR_TEST is in its default value)
+ *      - glBlendFuncSeparate() state (but GL_BLEND is in its default value)
+ *      - glClearColor() state
+ *      - mpv may overwrite the callback set with glDebugMessageCallback()
+ *      - mpv always disables GL_DITHER at init
+ *
+ * Messing with the state could be avoided by creating shared OpenGL contexts,
+ * but this is avoided for the sake of compatibility and interoperability.
+ *
+ * On OpenGL 2.1, mpv will strictly call functions like glGenTextures() to
+ * create OpenGL objects. You will have to do the same. This ensures that
+ * objects created by mpv and the API users don't clash. Also, legacy state
+ * must be either in its defaults, or not interfere with core state.
+ *
+ * API use
+ * -------
+ *
+ * The mpv_render_* API is used. That API supports multiple backends, and this
+ * section documents specifics for the OpenGL backend.
+ *
+ * Use mpv_render_context_create() with MPV_RENDER_PARAM_API_TYPE set to
+ * MPV_RENDER_API_TYPE_OPENGL, and MPV_RENDER_PARAM_OPENGL_INIT_PARAMS provided.
+ *
+ * Call mpv_render_context_render() with MPV_RENDER_PARAM_OPENGL_FBO to render
+ * the video frame to an FBO.
+ *
+ * Hardware decoding
+ * -----------------
+ *
+ * Hardware decoding via this API is fully supported, but requires some
+ * additional setup. (At least if direct hardware decoding modes are wanted,
+ * instead of copying back surface data from GPU to CPU RAM.)
+ *
+ * There may be certain requirements on the OpenGL implementation:
+ *
+ * - Windows: ANGLE is required (although in theory GL/DX interop could be used)
+ * - Intel/Linux: EGL is required, and also a glMPGetNativeDisplay() callback
+ *                must be provided (see sections below)
+ * - nVidia/Linux: Both GLX and EGL should work (GLX is required if vdpau is
+ *                 used, e.g. due to old drivers.)
+ * - OSX: CGL is required (CGLGetCurrentContext() returning non-NULL)
+ * - iOS: EAGL is required (EAGLContext.currentContext returning non-nil)
+ *
+ * Once these things are setup, hardware decoding can be enabled/disabled at
+ * any time by setting the "hwdec" property.
+ */
+
+/**
+ * For initializing the mpv OpenGL state via MPV_RENDER_PARAM_OPENGL_INIT_PARAMS.
+ */
+typedef struct mpv_opengl_init_params {
+    /**
+     * This retrieves OpenGL function pointers, and will use them in subsequent
+     * operation.
+     * Usually, GL context APIs do this for you (e.g. with glXGetProcAddressARB
+     * or wglGetProcAddress), but some APIs do not always return pointers for
+     * all standard functions (even if present); in this case you have to
+     * compensate by looking up these functions yourself and returning them
+     * from this callback.
+     */
+    void *(*get_proc_address)(void *ctx, const char *name);
+    /**
+     * Value passed as ctx parameter to get_proc_address().
+     */
+    void *get_proc_address_ctx;
+    /**
+     * This should not be used. The main purpose is signaling support for
+     * "GL_MP_MPGetNativeDisplay", which is needed for compatibility with the
+     * opengl_cb API only. Thus it's deprecated and will be removed or ignored
+     * when the opengl_cb API is removed.
+     */
+    const char *extra_exts;
+} mpv_opengl_init_params;
+
+/**
+ * For MPV_RENDER_PARAM_OPENGL_FBO.
+ */
+typedef struct mpv_opengl_fbo {
+    /**
+     * Framebuffer object name. This must be either a valid FBO generated by
+     * glGenFramebuffers() that is complete and color-renderable, or 0. If the
+     * value is 0, this refers to the OpenGL default framebuffer.
+     */
+    int fbo;
+    /**
+     * Valid dimensions. This must refer to the size of the framebuffer. This
+     * must always be set.
+     */
+    int w, h;
+    /**
+     * Underlying texture internal format (e.g. GL_RGBA8), or 0 if unknown. If
+     * this is the default framebuffer, this can be an equivalent.
+     */
+    int internal_format;
+} mpv_opengl_fbo;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif