geom.builder.h

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#pragma once
 
// #include "eu/render/color.h"
 
namespace eu::core
{
struct Geom;
}
 
namespace eu::core::geom
{
 
using Index = u64;
 
enum class SideCount
{
    one_sided,
    two_sided
};
 
enum class NormalsFacing
{
    In,
    Out
};
 
struct Vertex
{
    Index position;
    Index normal;
    Index texture;
    Index color;
 
    Vertex(Index pnt, Index clr);
    Vertex(Index a_position, Index a_normal, Index a_texture, Index a_color);
};
 
struct Triangle
{
    Vertex v0;
    Vertex v1;
    Vertex v2;
 
    Triangle(const Vertex& a, const Vertex& b, const Vertex& c);
};
 
using Influence4 = std::array<std::size_t, 4>;
 
struct Builder
{
    Index add_text_coord(const v2& tc);
    Index add_position(const v3& pos);
    Index add_normal(const n3& norm);
    Index add_color(const Lin_rgb& color);
    void add_weight(const v4& weight);
    void add_influence(const Influence4& weight);
 
    // find or add
    Index foa_text_coord(const v2& v, float max_diff);
    Index foa_position(const v3& pos, float max_diff);
    Index foa_normal(const n3& norm, float max_diff);
    Index foa_color(const Lin_rgb& color, float max_diff);
 
    Builder& add_triangle(const Triangle& t);
    Builder& add_quad(bool ccw, const Vertex& v0, const Vertex& v1, const Vertex& v2, const Vertex& v3);
    Builder& add_face(const std::vector<Vertex>&);
 
    Builder& move(const v3& dir);
    Builder& scale(float scale);
    Builder& invert_normals();
 
    [[nodiscard]] Geom to_geom() const;
 
    Builder& write_obj(const std::string& path);
 
    std::vector<std::vector<Vertex>> faces; // each face needs to have 3 or more vertices
    std::vector<v3> positions;
    std::vector<n3> normals;
    std::vector<v2> texcoords;
    std::vector<v3> lin_colors; 
    std::vector<v4> weights;
    std::vector<Influence4> influences;
};
 
 
 
Builder create_box(float x, float y, float z, NormalsFacing normals_facing, const Rgb& color = colors::white);
 
 
 
Builder create_xz_plane(float x, float z, bool invert, const Rgb& color = colors::white);
 
 
 
Builder create_xy_plane(float x, float y, SideCount two_sided, const Rgb& color = colors::white);
 
 
 
Builder create_uv_sphere(
    float diameter, int longitude_count, int latitude_count, NormalsFacing normals_facing, const Rgb& color = colors::white
);
 
}  //  namespace eu::core::geom