render_target.hpp

#pragma once
 
#include <bnb/utils/defs.hpp>
 
#include <memory>
 
namespace bnb::player_api::interfaces
{
    class render_target;
    class player;
} // namespace bnb::player_api::interfaces
 
namespace bnb::player_api
{
    using render_target_sptr = std::shared_ptr<bnb::player_api::interfaces::render_target>;
    using texture_t = uint64_t;
} // namespace bnb::player_api
 
namespace bnb::player_api::interfaces
{
 
    /**
     * Responsible for preparation for drawing frames to 'outputs'.
     * This part of the RenderTarget is owned and controlled only by the player
     */
    class BNB_EXPORT render_target
    {
    public:
        /**
         * Destroy render_target and release resources
         */
        virtual ~render_target() = default;
 
        /**
         * Attach render_target to the player. Called by the player on the render thread.
         *  @param player instance
         */
        virtual void attach(player& player) = 0;
 
        /**
         * Detach render_target from the player. Called by the player on the render thread.
         *  @param player instance
         */
        virtual void detach(player& player) = 0;
 
        /**
         * Prepare render target to offscreen rendering of the player
         *  @param width rendering surface width
         *  @param height rendering surface height
         */
        virtual void prepare_to_offscreen_render(int32_t width, int32_t height) = 0;
 
        /**
         * Prepare render target to screen rendering
         *  @param surface rendering surface
         */
        virtual void prepare_to_screen_render(void* surface) = 0;
 
        /**
         * Set presentation frame time
         * @param time_us time in microseconds
         */
        virtual void set_frame_time_us(uint64_t time_us) noexcept = 0;
 
        /**
         * Get frame time microseconds
         */
        virtual uint64_t get_frame_time_us() const noexcept = 0;
 
        /**
         * Get render surface size width
         */
        virtual int32_t get_render_width() const noexcept = 0;
 
        /**
         * Get render surface size height
         */
        virtual int32_t get_render_height() const noexcept = 0;
 
        /**
         * Returns the drawn texture.
         * With an OpenGL backend, to get an opengl texture you need to do this:
         * reinterpret_cast<GLuint>(render_terget->get_output_texture())
         */
        virtual texture_t get_output_texture() const noexcept = 0;
 
        /**
         * Draw the frame on the prepared surface
         * @param left viewport x coord
         * @param top viewport y coord
         * @param width of the viewport
         * @param height of the viewport
         * @param mat4 texture matrix
         */
        virtual void present(int32_t left, int32_t top, int32_t width, int32_t height, const float* const mat4) = 0;
    }; // class render_target
 
} // namespace bnb::player_api::interfaces