Faset_Engine/include/faset/render/renderer.hpp

#pragma once
#include <array>
#include <cstdint>
#include <filesystem>
#include <memory>
#include <string>
#include <vector>

namespace faset::render {
using Vec2 = std::array<float, 2>;
using Vec3 = std::array<float, 3>;
using Color = std::array<float, 4>;
using Mat4 = std::array<float, 16>;
inline constexpr Mat4 identity{1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
// Matrices are column-major, vectors are columns; clip depth is Vulkan's [0,1].
Mat4 multiply(const Mat4&, const Mat4&);
Mat4 transform(Vec3 position, Vec3 rotation = {}, Vec3 scale = {1, 1, 1});
Mat4 perspective(float vertical_fov_radians, float aspect, float near_plane, float far_plane);
Mat4 orthographic(float left, float right, float bottom, float top, float near_plane,
                  float far_plane);
Mat4 look_at(Vec3 eye, Vec3 target, Vec3 up = {0, 1, 0});
struct Vertex {
    Vec3 position{};
    Vec3 normal{0, 0, 1};
    Color color{1, 1, 1, 1};
    Vec2 uv{};
};
struct Mesh {
    std::vector<Vertex> vertices;
    std::vector<std::uint32_t> indices;
};
std::shared_ptr<const Mesh> cube_mesh();
struct Texture;
struct DrawItem {
    std::shared_ptr<const Mesh> mesh;
    Mat4 model{identity};
    Color color{1, 1, 1, 1};
    float roughness{0.65f};
    float metallic{0.0f};
    bool cast_shadow{true};
    std::shared_ptr<const Texture> texture;
};
struct Sprite {
    Vec3 position{};
    Vec2 size{1, 1};
    Color color{1, 1, 1, 1};
    float rotation{};
    std::shared_ptr<const Texture> texture;
};
struct Texture {
    std::uint32_t width{}, height{};
    std::vector<std::uint8_t> rgba;
    std::uint64_t revision{};
    bool srgb{false};
};
struct Quad {
    float x{}, y{}, width{}, height{};
    Color color{1, 1, 1, 1};
    std::shared_ptr<const Texture> texture;
    std::array<float, 4> uv_rect{0, 0, 1, 1};
};
struct Text {
    float x{}, y{};
    std::string value;
    Color color{0.85f, 0.87f, 0.90f, 1};
    float size{14};
};
struct Snapshot {
    // Optional scene viewport in drawable pixels (x, y, width, height); zero size uses the full
    // target.
    std::array<float, 4> scene_rect{};
    Mat4 view_projection{identity};
    Vec3 eye{4, 3, 5};
    Vec3 light_direction{-0.5f, -1, -0.3f};
    Color clear_color{0.055f, 0.065f, 0.085f, 1};
    std::vector<DrawItem> draws;
    std::vector<Sprite> sprites;
    // UI coordinates are drawable pixels, top-left origin. Order is preserved per list.
    std::vector<Quad> ui_quads;
    std::vector<Text> ui_text;
};
struct RendererConfig {
    std::uint32_t width{1280}, height{720};
    std::string title{"Faset Engine"};
    bool headless{false};
    bool validation{true};
};
struct Event {
    enum class Type {
        Quit,
        Resize,
        FocusGained,
        FocusLost,
        MouseMove,
        MouseDown,
        MouseUp,
        Wheel,
        KeyDown,
        KeyUp,
        TextInput,
        TextEditing
    };
    Type type{};
    float x{}, y{};
    int button{};
    std::string key;
    std::string text;
    bool control{}, shift{}, alt{}, repeat{};
    int edit_start{}, edit_length{};
};
struct FrameStats {
    std::uint64_t frame{};
    std::uint32_t vertices{}, draw_calls{}, culled_meshes{}, validation_errors{};
    double cpu_ms{}, gpu_ms{};
    std::string device;
};
class Renderer {
  public:
    explicit Renderer(const RendererConfig& = {});
    ~Renderer();
    Renderer(Renderer&&) noexcept;
    Renderer& operator=(Renderer&&) noexcept;
    Renderer(const Renderer&) = delete;
    Renderer& operator=(const Renderer&) = delete;
    std::vector<Event> poll_events();
    void render(const Snapshot&);
    void resize(std::uint32_t width, std::uint32_t height);
    // Rebuilds graphics pipelines from SPIR-V; a failure preserves the current pipelines.
    bool reload_shaders(std::string& error);
    // Saves the latest completed frame as a portable RGB PPM image.
    void capture(const std::filesystem::path&);
    std::vector<std::uint8_t> pixels() const;
    std::uint32_t width() const;
    std::uint32_t height() const;
    bool should_close() const;
    const FrameStats& stats() const;
    void set_title(const std::string&);
    void set_text_input(bool enabled);
    void set_text_input_area(float x, float y, float width, float height);
    void set_clipboard(const std::string&);
    std::string clipboard() const;

  private:
    struct Impl;
    std::unique_ptr<Impl> impl_;
};
} // namespace faset::render