OpenSiv3D実装会(6/24)で作ったサンプル２

main.cpp

//
// Siv3Dで3D
//

# include <Siv3D.hpp>
// ベクトル＆行列ライブラリ 
// SOURCE https://glm.g-truc.net/0.9.8/index.html
# include "glm/glm.hpp"
# include "glm/gtc/matrix_transform.hpp"
# include "glm/gtx/transform.hpp"
# include "glm/gtx/string_cast.hpp"


void Main()
{
  const int window_width  = 960;
  const int window_height = 640;

  Window::Resize(window_width, window_height);

  glm::vec4 vertex[] {
    // TOP
    { -1, -1, -1, 1 },
    {  1, -1, -1, 1 },
    {  1, -1,  1, 1 },
    { -1, -1,  1, 1 },
    // BOTTOM
    { -1,  1, -1, 1 },
    { -1,  1,  1, 1 },
    {  1,  1,  1, 1 },
    {  1,  1, -1, 1 },
    // LEFT
    { -1, -1, -1, 1 },
    { -1, -1,  1, 1 },
    { -1,  1,  1, 1 },
    { -1,  1, -1, 1 },
    // RIGHT
    {  1, -1, -1, 1 },
    {  1,  1, -1, 1 },
    {  1,  1,  1, 1 },
    {  1, -1,  1, 1 },
    // FRONT
    { -1, -1,  1, 1 },
    {  1, -1,  1, 1 },
    {  1,  1,  1, 1 },
    { -1,  1,  1, 1 },
    // BACK
    { -1, -1, -1, 1 },
    { -1,  1, -1, 1 },
    {  1,  1, -1, 1 },
    {  1, -1, -1, 1 },
  };

  auto proj_matrix = glm::perspective(float(M_PI) * 60.0f / 180.0f, float(window_width) / float(window_height), 0.1f, 100.0f);
  auto view_matrix = glm::translate(glm::vec3(0, 0, -30.0));

  ColorF color[] = {
    { 0, 0, 1 },
    { 0, 1, 0 },
    { 0, 1, 1 },
    { 1, 0, 0 },
    { 1, 0, 1 },
    { 1, 1, 0 },
  };

  float yaw   = 0.0f;
  float pitch = 0.0f;

  float yaw2   = 0.0f;
  float pitch2 = 0.0f;

	while (System::Update())
	{
    auto model_matrix = glm::rotate(yaw, glm::vec3(0, 1, 0)) * glm::rotate(pitch, glm::vec3(1, 0, 0));
    yaw   += 0.005f;
    pitch += 0.003f;

    auto yy = yaw2;
    auto pp = pitch2;
    yaw2   += 0.02f;
    pitch2 += 0.03f;

    for (int x = -3; x <= 3; ++x)
    {
      for (int y = -3; y <= 3; ++y)
      {
        for (int z = -3; z <= 3; ++z)
        {
          auto rm = glm::rotate(yy, glm::vec3(0, 1, 0)) * glm::rotate(pp, glm::vec3(1, 0, 0));
          auto m = model_matrix * glm::translate(glm::vec3(x * 3, y * 3, z * 3)) * rm;

          yy += 0.005f;
          pp += 0.006f;

          for (int i = 0; i < 6; ++i)
          {
            glm::vec2 p[4];
            glm::vec3 p3[4];
            for (int j = 0; j < 4; ++j)
            {
              // 簡易透視変換
              auto pos = view_matrix * m * vertex[i * 4 + j];
              p3[j] = pos;
              pos = proj_matrix * pos;
              pos = pos / pos.w;

              // 単位座標→表示画面座標
              glm::vec2 p2(pos.x * (window_width / 2), pos.y * (window_height / 2));
              p2 = p2 + glm::vec2(window_width / 2, window_height / 2);
              p[j] = p2;
            }

            // 表裏判定
            auto a = p[1] - p[0];
            auto b = p[2] - p[0];
            auto cross = a.x * b.y - b.x * a.y;
            if (cross > 0.0f)
            {
              auto v1 = p3[1] - p3[0];
              auto v2 = p3[2] - p3[0];
              auto cv = glm::normalize(glm::cross(v1, v2));
              auto dot = glm::dot(cv, glm::vec3(0, 0, 1));

              Quad(Vec2(p[0].x, p[0].y),
                   Vec2(p[1].x, p[1].y),
                   Vec2(p[2].x, p[2].y),
                   Vec2(p[3].x, p[3].y)).draw(color[i] * dot);
            }
          }
        }
      }
    }
	}
}