MinusculeRender/src/triangle.h

// Copyright 2024 Bytedance Inc. All Rights Reserved.
// Author: tianlei.richard@qq.com (tianlei.richard)

#pragma once

#include "common.h"
#include <Eigen/Geometry>
#include <array>

class Triangle {
public:
  using AffineTransformType = Eigen::Transform<double, 3, Eigen::Affine>;
  using ProjectiveTransformType =
      Eigen::Transform<double, 3, Eigen::Projective>;

private:
  using HomoPointType = Eigen::Vector4d;

public:
  Triangle(const Point3d &a, const Point3d &b, const Point3d &c);
  Triangle(const HomoPointType &a, const HomoPointType &b,
           const HomoPointType &c);

  template <int size>
  std::array<Eigen::Vector<double, size>, 3> get_points() const {
    return std::array<Eigen::Vector<double, size>, 3>{
        (points_[0]).head(size),
        (points_[1]).head(size),
        (points_[2]).head(size),
    };
  }

public:
  BBox axis_align_bbox() const;
  Vector3d normal_vector() const;

  void affine_transform(const AffineTransformType &m);
  void projective_transform(const ProjectiveTransformType &m);

private:
  std::array<Point3d, 3> points_;
};