/*
 * yt - A fully featured command line YouTube client
 *
 * Copyright (C) 2018 the mpv developers
 * Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * This file is part of Yt.
 *
 * You should have received a copy of the License along with this program.
 * If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
 */

#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 the native display resource needs
   *                to be provided (e.g. MPV_RENDER_PARAM_X11_DISPLAY for X11
   * and MPV_RENDER_PARAM_WL_DISPLAY for Wayland)
   * - nVidia/Linux: Both GLX and EGL should work (GLX is required if vdpau is
   *                 used, e.g. due to old drivers.)
   * - macOS: 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, you can simply call the GL context APIs from this callback
     * (e.g. 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
     * when libmpv wants to resolve them through this callback. libmpv will not
     * normally attempt to resolve GL functions on its own, nor does it link to
     * GL libraries directly.
     */
    void *(*get_proc_address) (void *ctx, const char *name);
    /**
     * Value passed as ctx parameter to get_proc_address().
     */
    void *get_proc_address_ctx;
  } 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;

  /**
   * Deprecated. For MPV_RENDER_PARAM_DRM_DISPLAY.
   */
  typedef struct mpv_opengl_drm_params
  {
    int fd;
    int crtc_id;
    int connector_id;
    struct _drmModeAtomicReq **atomic_request_ptr;
    int render_fd;
  } mpv_opengl_drm_params;

  /**
   * For MPV_RENDER_PARAM_DRM_DRAW_SURFACE_SIZE.
   */
  typedef struct mpv_opengl_drm_draw_surface_size
  {
    /**
     * size of the draw plane surface in pixels.
     */
    int width, height;
  } mpv_opengl_drm_draw_surface_size;

  /**
   * For MPV_RENDER_PARAM_DRM_DISPLAY_V2.
   */
  typedef struct mpv_opengl_drm_params_v2
  {
    /**
     * DRM fd (int). Set to -1 if invalid.
     */
    int fd;

    /**
     * Currently used crtc id
     */
    int crtc_id;

    /**
     * Currently used connector id
     */
    int connector_id;

    /**
     * Pointer to a drmModeAtomicReq pointer that is being used for the
     * renderloop. This pointer should hold a pointer to the atomic request
     * pointer The atomic request pointer is usually changed at every
     * renderloop.
     */
    struct _drmModeAtomicReq **atomic_request_ptr;

    /**
     * DRM render node. Used for VAAPI interop.
     * Set to -1 if invalid.
     */
    int render_fd;
  } mpv_opengl_drm_params_v2;

/**
 * For backwards compatibility with the old naming of
 * mpv_opengl_drm_draw_surface_size
 */
#define mpv_opengl_drm_osd_size mpv_opengl_drm_draw_surface_size

#ifdef __cplusplus
}
#endif

#endif