computer-graphics-0/src/drawing_assets.hpp

#pragma once

#include <type_traits>

#include "frame.hpp"

void draw_circle(Frame *frame, int cx, int cy, int radius, COLOR outline);

inline void draw_circle(Frame *frame, Point c, int radius, COLOR outline) {
    draw_circle(frame, c.x, c.y, radius, outline);
}

void draw_line(Frame *frame, int x1, int y1, int x2, int y2, COLOR color);

inline void draw_line(Frame *frame, Point p1, Point p2, COLOR color) {
    draw_line(frame, p1.x, p1.y, p2.x, p2.y, color);
}

template<class ...>
struct draw_polyline_ {
    template<class ...point_t>
    friend
    void draw_polyline(Frame *frame, COLOR color, point_t ...points);

    template<class ...>
    friend
    struct draw_polyline_;
private:
};


template<class p0_t, class p1_t, class ...pp_t>
struct draw_polyline_<p0_t, p1_t, pp_t...> {
    template<class ...point_t>
    friend
    void draw_polyline(Frame *frame, COLOR color, point_t ...points);

    template<class ...>
    friend
    struct draw_polyline_;
private:
    static_assert(std::is_same_v<p0_t, Point>);
    static_assert(std::is_same_v<p1_t, Point>);

    static void draw(Frame *frame, COLOR color, p0_t p0, p1_t p1, pp_t ...points) {
        draw_line(frame, p0, p1, color);
        draw_polyline_<p1_t, pp_t...>::draw(frame, color, p1, points...);
    }

    static constexpr bool HAS_ANY = true;

    static Point first(p0_t p0, p1_t p1, pp_t ...points) {
        return p0;
    }

    static Point last(p0_t p0, p1_t p1, pp_t ...points) {
        return draw_polyline_<p1_t, pp_t...>::last(p1, points...);
    }
};

template<class p0_t>
struct draw_polyline_<p0_t> {
    template<class ...point_t>
    friend
    void draw_polyline(Frame *frame, COLOR color, point_t ...points);

    template<class ...>
    friend
    struct draw_polyline_;
private:
    static_assert(std::is_same_v<p0_t, Point>);

    static void draw(Frame *frame, COLOR color, p0_t p0) {}

    static constexpr bool HAS_ANY = true;


    static Point first(p0_t p0) {
        return p0;
    }

    static Point last(p0_t p0) {
        return p0;
    }
};

template<>
struct draw_polyline_<> {
    template<class ...point_t>
    friend
    void draw_polyline(Frame *frame, COLOR color, point_t ...points);

    template<class ...>
    friend
    struct draw_polyline_;
private:
    static void draw(Frame *frame, COLOR color) {}

    static constexpr bool HAS_ANY = false;

    static Point first() {
        return Point{0, 0};
    }

    static Point last() {
        return Point{0, 0};
    }
};

template<class ...point_t>
void draw_polyline(Frame *frame, COLOR color, point_t ...points) {
    if constexpr (!draw_polyline_<point_t...>::HAS_ANY) {}
    else {
        draw_polyline_<point_t...>::draw(frame, color, points...);
        draw_line(frame, draw_polyline_<point_t...>::last(points...), draw_polyline_<point_t...>::first(points...), color);
    }
}

class Shader {
public:
    [[nodiscard]] virtual COLOR get_color(int x, int y) const = 0;
};

class MonoShader : public Shader {
private:
    COLOR color;
public:
    explicit MonoShader(COLOR color) : color{color} {}

    [[nodiscard]] COLOR get_color(int x, int y) const override {
        return this->color;
    }
};

class BarycentricInterpolatorShader : public Shader {
private:
    int x0, y0, x1, y1, x2, y2, S;
    COLOR C0, C1, C2;
public:
    BarycentricInterpolatorShader(float _x0, float _y0, float _x1, float _y1, float
    _x2, float _y2, COLOR A0, COLOR A1, COLOR A2) :
            x0(_x0), y0(_y0), x1(_x1), y1(_y1), x2(_x2), y2(_y2),
            S((_y1 - _y2) * (_x0 - _x2) + (_x2 - _x1) * (_y0 - _y2)), C0(A0), C1(A1),
            C2(A2) {
    }

    COLOR get_color(int x, int y) const override {
// Барицентрическая интерполяция
        float h0 = ((y1 - y2) * (x - x2) + (x2 - x1) * (y - y2)) / S;
        float h1 = ((y2 - y0) * (x - x2) + (x0 - x2) * (y - y2)) / S;
        float h2 = 1 - h0 - h1;
        float r = h0 * C0.red + h1 * C1.red + h2 * C2.red;
        float g = h0 * C0.green + h1 * C1.green + h2 * C2.green;
        float b = h0 * C0.blue + h1 * C1.blue + h2 * C2.blue;
        float a = h0 * C0.alpha + h1 * C1.alpha + h2 * C2.alpha;
        return COLOR(r, g, b, a);
    }
};

void fill_triangle(Frame *f, int x0, int y0, int x1, int y1, int x2, int y2, Shader const *shader);


inline void fill_triangle(Frame *f, Point p0, Point p1, Point p2, Shader const *shader) {
    fill_triangle(f, p0.x, p0.y, p1.x, p1.y, p2.x, p2.y, shader);
}

inline void fill_triangle(Frame *f, int x0, int y0, int x1, int y1, int x2, int y2, COLOR color) {
    MonoShader s{color};
    fill_triangle(f, x0, y0, x1, y1, x2, y2, &s);

}


inline void fill_triangle(Frame *f, Point p0, Point p1, Point p2, COLOR color) {
    MonoShader s{color};
    fill_triangle(f, p0.x, p0.y, p1.x, p1.y, p2.x, p2.y, &s);
}

COLOR ColorFromHSV(double hue, double saturation, double value);