Games101 作业 05

//Renderer.cpp

Render()// 这里你需要为每个像素生成一条对应的光线，

        // 然后调用函数 castRay () 来得到颜色，

        // 最后将颜色存储在帧缓冲区的相应像素中。

//Triangle.hpp

rayTriangleIntersect()//v0, v1, v2 是三角形的三个顶点，

                      //orig 是光线的起点，dir 是光线单位化的方向向量。

                      //tnear, u, v 是你需要使用我们课上推导的

                      //Moller-Trumbore 算法来更新的参数。

void Renderer::Render(const Scene &scene) {

  std::vector<Vector3f> framebuffer(scene.width * scene.height);

  float scale = std::tan(deg2rad(scene.fov * 0.5f));

  float imageAspectRatio = scene.width / (float)scene.height;

  // Use this variable as the eye position to start your rays.

  Vector3f eye_pos(0);

  int m = 0;

  for (int j = 0; j < scene.height; ++j) {

    for (int i = 0; i < scene.width; ++i) {

      // generate primary ray direction

      float x;

      float y;

      // Find the x and y positions of the current pixel to get the

      // direction vector that passes through it. Also, don't forget to

      // multiply both of them with the variable *scale*, and x

      // (horizontal) variable with the *imageAspectRatio*

      x = (2 * (i + 0.5) / (float)scene.width - 1) * scale * imageAspectRatio;

      y = (1 - 2 * (j + 0.5) / (float)scene.height) * scale;

      Vector3f dir =

          Vector3f(x, y, -1); // Don't forget to normalize this direction!

      dir = normalize(dir);

      framebuffer[m++] = castRay(eye_pos, dir, scene, 0);

    }

    UpdateProgress(j / (float)scene.height);

  }

  // save framebuffer to file

  FILE *fp = fopen("binary.ppm", "wb");

  (void)fprintf(fp, "P6\n%d %d\n255\n", scene.width, scene.height);

  for (auto i = 0; i < scene.height * scene.width; ++i) {

    static unsigned char color[3];

    color[0] = (char)(255 * clamp(0, 1, framebuffer[i].x));

    color[1] = (char)(255 * clamp(0, 1, framebuffer[i].y));

    color[2] = (char)(255 * clamp(0, 1, framebuffer[i].z));

    fwrite(color, 1, 3, fp);

  }

  fclose(fp);

}

bool rayTriangleIntersect(const Vector3f &v0, const Vector3f &v1,

                          const Vector3f &v2, const Vector3f &orig,

                          const Vector3f &dir, float &tnear, float &u,

                          float &v) {

  // Implement this function that tests whether the triangle

  // that's specified bt v0, v1 and v2 intersects with the ray (whose

  // origin is *orig* and direction is *dir*)

  // Also don't forget to update tnear, u and v.

  // Moller-Trumbore

  Vector3f e1 = v1 - v0;

  Vector3f e2 = v2 - v0;

  Vector3f s = orig - v0;

  Vector3f s1 = crossProduct(dir, e2);

  Vector3f s2 = crossProduct(s, e1);

  float t = dotProduct(s2, e2) / dotProduct(s1, e1);

  float b1 = dotProduct(s1, s) / dotProduct(s1, e1);

  float b2 = dotProduct(s2, dir) / dotProduct(s1, e1);

  if (t > 0.0 && b1 > 0.0 && b2 > 0.0 && (1 - b1 - b2) > 0.0) {

    tnear = t;

    u = b1;

    v = b2;

    return true;

  }

  return false;

}