レイキャストを実装してみる(5) 複数のオブジェクト

#pragma once

#include "Grid.hpp"

#include <array>
#include <vector>
#include <memory>

//////////////////////////////////////////////
//////////////////////////////////////////////

// 三次元オブジェクトのスーパークラス
class object_3d {
protected:
  glm::vec3 _color;
public:

  object_3d(const glm::vec3& color_) :_color(color_) {}
  object_3d() {}

  virtual bool intersect(
    glm::vec3* pos_,
    glm::vec3* color_,
    glm::vec3* normal_,
    float* distance_,
    const std::array<glm::vec3, 2>& ray_)const = 0;

  const glm::vec3& color()const { return _color; }
  glm::vec3& color() { return _color; }

};

// 球オブジェクト
class object_sphere:public object_3d {
  glm::vec3 _center;
  float _r;
public:
  object_sphere(glm::vec3 center_, glm::vec3 color_,float radius_) :
    _center(center_),_r(radius_), object_3d(color_) {}
  object_sphere() {}

  virtual bool intersect(
    glm::vec3* pos_, 
    glm::vec3* color_,
    glm::vec3* normal_,
    float* distance_,
    const std::array<glm::vec3, 2>& ray_)const override;

};

// 三角形オブジェクト
class object_triangle :public object_3d {
  std::array<glm::vec3,3> _points;
public:
  object_triangle(
    std::array<glm::vec3, 3> points_, glm::vec3 color_) :
    _points(points_), object_3d(color_){}
  object_triangle() {}

  bool intersect(
    glm::vec3* pos_,
    glm::vec3* color_,
    glm::vec3* normal_,
    float* distance_,
    const std::array<glm::vec3, 2>& ray_)const override;


};

//////////////////////////////////////////////
//////////////////////////////////////////////
// ポイントライト
class light_point {
  glm::vec3 _position;
  glm::vec3 _diffuse_color;
  glm::vec3 _ambient_color;
  glm::vec3 _specular_color;
public:

  light_point(
    const glm::vec3& position_, 
    const glm::vec3& diffuse_color_,
    const glm::vec3& ambient_color_,
    const glm::vec3& specular_color_
  ) :
    _position(position_), 
    _diffuse_color(diffuse_color_),
    _ambient_color(ambient_color_),
    _specular_color(specular_color_)
  {}
  light_point() {}

  glm::vec3 calc_vector_point_to_light(const glm::vec3& point_)const {
    // from -> _position
    return glm::normalize(_position - point_);
  }

  const glm::vec3& position()const {return _position;}
  glm::vec3& position() { return _position; }

  const glm::vec3& diffuse_color()const {return _diffuse_color;}
  glm::vec3& diffuse_color() { return _diffuse_color; }

  const glm::vec3& ambient_color()const { return _ambient_color; }
  glm::vec3& ambient_color() { return _ambient_color; }

  const glm::vec3& specular_color()const { return _specular_color; }
  glm::vec3& specular_color() { return _specular_color; }

};

struct hit_pixel_t {
  glm::vec3 _position;
  glm::vec3 _color;
  hit_pixel_t(const glm::vec3& position_, const glm::vec3& color_) :
    _position(position_), _color(color_) {}

};


// レイキャスト用のクラス
class my_raycast {
  grid g[2];
  float _startZ;
  float _endZ;
  int _pxwidth;
  int _pxheight;
public:

  glm::vec3 get_eye_position()const {
    float a = g[0].ywidth() / 2.0;
    float b = g[1].ywidth() / 2.0;
    float d = glm::length(g[1].center() - g[0].center());
    float c = a * d / (b - a);


    // 始点　→　終点
    glm::vec3 veceye = g[1].center() - g[0].center();
    veceye = glm::normalize(veceye);
    return g[0].center()  - veceye * c;
  }

  my_raycast() {}

  int width()const { return _pxwidth; }
  int height()const { return _pxheight; }

  // レイの開始点となるグリッド、終点となるグリッドを作成する
  void set(const float startZ_, const float endZ_, const int pxwidth_, const int pxheight_);

  //グリッド取得
  const grid& get_grid(const size_t index)const {
    return g[index];
  }

  //グリッドから作成するレイの数を取得
  int ray_count() {
    return g[0].cellCount();
  }

  //グリッドから作成するレイを取得
  std::array<glm::vec3, 2> get_ray(const size_t index)const;

  //始点グリッド、終点グリッドの中間の位置を取得（表示用）
  float lookatZ()const {
    return (_startZ + _endZ) / 2.f;
  }


  //////////////////////////////////////////////
  //////////////////////////////////////////////

private:

  // オブジェクト一覧
  std::vector< std::shared_ptr<object_3d> > _objlist;


  std::vector< hit_pixel_t > _hits;
public:
  void raycast();
  std::vector< hit_pixel_t >& get_intersects() {return _hits;}
  
  void set_object(const object_sphere& obj_);
  void set_object(const object_triangle& obj_);
  
  //////////////////////////////
private:
  light_point _light;
public:
  void set_light(const light_point& light_);

  const light_point& get_light()const { return _light; }
};

// objectNormal 面法線
// lightDirection そのポイント→光源へのベクトル
// lightColor ライトの色
inline glm::vec3 calc_diffuse(
  const glm::vec3& lightDiffuse, 
  const glm::vec3& MaterialDiffuse, 
  const glm::vec3& lightIncidence,
  const glm::vec3& objectNormal) 
{
  // 拡散反射は「そのポイント→光源」と面法線の内積を取る

  float sDotN = glm::max(glm::dot(-lightIncidence, objectNormal), 0.f);

  return lightDiffuse * MaterialDiffuse *sDotN;
}

inline glm::vec3 calc_ambient(
  const glm::vec3& LightAmbient, 
  const glm::vec3& MaterialAmbient) 
{
  return LightAmbient * MaterialAmbient;
}

// https://araramistudio.jimdo.com/2017/10/02/%E3%83%97%E3%83%AD%E3%82%B0%E3%83%A9%E3%83%9F%E3%83%B3%E3%82%B0-directx-11%E3%81%A7%E9%8F%A1%E9%9D%A2%E5%8F%8D%E5%B0%84-specular-reflection/
// https://amengol.github.io/game_physics/using-glm-reflect-to-react/
// https://learnopengl.com/Lighting/Basic-Lighting

inline glm::vec3 calc_specular(
  const glm::vec3& eyePosition,
  const glm::vec3& lightSpecularColor,
  const glm::vec3& materialSpecularColor,
  const glm::vec3& lightIncidence, // 入射
  const float materialShininess,
  const glm::vec3& objectNormal,
  const glm::vec3& objectPosition
)
{

  glm::vec3 VertexToEye = glm::normalize(eyePosition - objectPosition);


  glm::vec3 LightReflect = glm::normalize(glm::reflect(lightIncidence, objectNormal));

  float SpecularFactor = glm::pow(glm::max(glm::dot(VertexToEye, LightReflect),0.f), materialShininess);

  glm::vec3 SpecularColor(0, 0, 0);
  SpecularColor = SpecularFactor * lightSpecularColor * materialSpecularColor;

  return SpecularColor;

}

#include "raycast.hpp"

#include <glm/gtx/intersect.hpp>
#include <glm/gtx/normal.hpp >

#include <memory>

bool object_sphere::intersect(
  glm::vec3* pos_, 
  glm::vec3* color_,
  glm::vec3* normal_,
  float* distance_,
  const std::array<glm::vec3, 2>& ray_) const{

  glm::vec3 nray = glm::normalize(ray_[1] - ray_[0]);

  float distance;

  bool valid = glm::intersectRaySphere(ray_[0], nray, _center, _r*_r, distance);

  //レイが衝突した点の座標
  *pos_ = ray_[0] + nray * distance;

  //色の設定
  *color_ = _color;


  //面法線
  // 球中心 → 衝突点
  *normal_ = glm::normalize(*pos_ - _center);

  *distance_ = distance;

  return valid;
}


bool object_triangle::intersect(
  glm::vec3* pos_,
  glm::vec3* color_,
  glm::vec3* normal_,
  float* distance_,
  const std::array<glm::vec3, 2>& ray_)const {

  glm::vec3 nray = glm::normalize(ray_[1] - ray_[0]);

  float distance;

  glm::vec2 bary;
  
  bool valid = glm::intersectRayTriangle(
    ray_[0],
    nray,
    _points[0],
    _points[1],
    _points[2],
    bary,
    distance
  );

  //レイが衝突した点の座標
  *pos_ = ray_[0] + nray * distance;


  //色の設定
  *color_ = _color;

  //面法線
  *normal_ = glm::triangleNormal(
    _points[0],
    _points[1],
    _points[2]
    ); // normalize済


  *distance_ = distance;
  return valid;

}



void my_raycast::set(const float startZ_, const float endZ_, const int pxwidth_, const int pxheight_) {
  _startZ = startZ_;
  _endZ = endZ_;

  _pxwidth = pxwidth_;
  _pxheight = pxheight_;

  glm::vec3 vecx(1, 0, 0);
  glm::vec3 vecy(0, 1, 0);

  g[0] = grid(
    vecx,
    vecy,
    glm::vec3(0, 0, _startZ),
    1.f, 1.f,
    pxwidth_, pxheight_
  );
  g[1] = grid(
    vecx,
    vecy,
    glm::vec3(0, 0, _endZ),
    2.f, 2.f,
    pxwidth_, pxheight_
  );

}


std::array<glm::vec3, 2> my_raycast::get_ray(const size_t index)const {
  return
    std::array<glm::vec3, 2>{
    g[0][index].center(),
      g[1][index].center()
  };

}

void my_raycast::set_object(const object_sphere& obj_) {
  _objlist.push_back(std::make_shared<object_sphere>(obj_));
}
void my_raycast::set_object(const object_triangle& obj_) {
  _objlist.push_back(std::make_shared<object_triangle>(obj_));
}

void my_raycast::set_light(const light_point& light_) {
  _light = light_;
}

void my_raycast::raycast() {

  // 結果の初期化
  float inf = std::numeric_limits<float>::infinity();
  _hits.clear();
  _hits.resize(_pxwidth * _pxheight,
    hit_pixel_t(
      glm::vec3(inf, inf, inf),
      glm::vec3(0, 0, 0)
    )
  );

  for (size_t i = 0; i < _pxwidth * _pxheight; i++) {

    auto ray = get_ray(i);

    glm::vec3 p; // レイがヒットした座標
    glm::vec3 c; // レイがヒットした位置の色
    glm::vec3 n; // レイがヒットした位置の法線

    float distance = (std::numeric_limits<float>::max)();
    bool hit = false;
    for (auto _obj : _objlist) {
      float _tmpdist;
      glm::vec3 tmp_p;
      glm::vec3 tmp_c;
      glm::vec3 tmp_n;

      if (_obj->intersect(&tmp_p, &tmp_c, &tmp_n, &_tmpdist, ray) == true) {
        if (_tmpdist < distance) {
          p = tmp_p;
          c = tmp_c;
          n = tmp_n;
        }
        hit = true;
      };

      if (hit) {
        _hits[i]._position = p;

        // ライトの入射ベクトル
        glm::vec3 lightIncidence = -_light.calc_vector_point_to_light(p);

        glm::vec3 diffuse = calc_diffuse(_light.diffuse_color(), c, lightIncidence, n);

        glm::vec3 specular = calc_specular(
          get_eye_position(),
          _light.specular_color(),
          c,
          lightIncidence,
          80, n, p);

        glm::vec3 ambient = calc_ambient(
          _light.ambient_color(), c
        );

        _hits[i]._color = ambient + diffuse + specular;
      }