renderer.hpp

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
#pragma once


#include <planet/sdl/handle.hpp>
#include <planet/ui/panel.hpp>

#include <felspar/coro/stream.hpp>
#include <felspar/exceptions.hpp>


#include <SDL.h>
#undef main

#include <cstdint>
#include <span>


namespace planet::sdl {


    class texture;
    class window;

If a drawing API fails then throw an exception

26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
    inline int drawing_worked(
            int const e,
            felspar::source_location const &loc =
                    felspar::source_location::current()) {
        if (e < 0) [[unlikely]] {
            throw felspar::stdexcept::runtime_error{
                    std::string{"Drawing API failed "} + SDL_GetError(), loc};
        } else {
            return e;
        }
    }


    class renderer final {
        friend class window;
        window &win;
        handle<SDL_Renderer, SDL_DestroyRenderer> pr;

Only creatable by the window

45
46
47
48
        renderer(window &);

      public:
        SDL_Renderer *get() const noexcept { return pr.get(); }

A representation of the screen the renderer is drawing to. Using this allows for global management of the coordinate system the application uses

53
        ui::panel screen;

Render function

Describe the last frame that has been rendered. Typically this is done with an instance of the render_loop using something like:

co_yield renderer.present();

65
66
67
        struct frame {
            std::size_t number = {};
        };

Frame presentation

Clear draw commands ready for next frame

73
        void clear();

Send the current draw commands to the screen

75
        [[nodiscard]] frame present();

Graphics APIs

All of these APIs use the SDL coordinate space, with no adjustment form screen member coordinate space.

Graphics APIs in pixel coordinate space

85
86
87
88
89
90
91
92
93
94
95
96
97
        void colour(std::uint8_t r, std::uint8_t g, std::uint8_t b) const;
        void colour(SDL_Color const &) const;
        void line(int x1, int y1, int x2, int y2) const;
        void lines(std::span<SDL_Point>) const;
        void copy(texture const &, int x, int y);
        void copy(texture const &, int x, int y, int w, int h);

      private:
        frame current_frame = {};
    };


}