From acd472bacf798760fc249e12e6f456695f6afb74 Mon Sep 17 00:00:00 2001
From: "tianlei.richard" <tianlei.richard@bytedance.com>
Date: Fri, 29 Mar 2024 18:09:16 +0800
Subject: [PATCH] complete phone shading impl.

---
 src/mesh.cc           |  44 +++++++++++--------
 src/mesh.h            |  18 ++++----
 src/minus_renderer.cc | 100 ++++++++++++++++++------------------------
 src/minus_renderer.h  |   2 +-
 src/phone_material.cc |   8 ++--
 src/phone_material.h  |   4 +-
 src/rasterizer.cc     |  54 +++++++++++------------
 src/rasterizer.h      |   4 +-
 src/triangle.cc       |  14 +++---
 src/triangle.h        |   5 ++-
 src/util/math_util.h  |  15 +++++--
 11 files changed, 137 insertions(+), 131 deletions(-)

diff --git a/src/mesh.cc b/src/mesh.cc
index 23663b9..36aafc7 100644
--- a/src/mesh.cc
+++ b/src/mesh.cc
@@ -11,31 +11,39 @@
 #define OBJL_VEC3_TO_EIGEN_VECTOR(objl_v)                                      \
   Eigen::Vector3d { objl_v.X, objl_v.Y, objl_v.Z }
 
-Mesh::Mesh(const std::vector<std::shared_ptr<Vertex>> &vertices,
-           const std::vector<Triangle> &primitives,
+Mesh::Mesh(const std::vector<Vertex> &vertices,
+           const std::vector<std::array<size_t, 3>> &indices,
            const std::shared_ptr<PhoneMaterial> &phone_material)
-    : vertices_(vertices), primitives_(primitives), material_(phone_material) {}
+    : vertices_(vertices), indices_(indices), material_(phone_material) {}
 
-std::vector<std::shared_ptr<Vertex>>::size_type Mesh::get_vertex_size() const {
+std::vector<Vertex> &Mesh::get_vertices() { return vertices_; }
+
+std::vector<Vertex>::size_type Mesh::get_vertex_size() const {
   return vertices_.size();
 };
 
 const decltype(Vertex::texture_coordinate) &
 Mesh::get_texture_coordinate(const unsigned int index) const {
-  return (vertices_[index])->texture_coordinate;
+  return (vertices_[index]).texture_coordinate;
 }
 
 Point3d Mesh::get_normal_vector(const unsigned int index) const {
-  return (vertices_[index])->normal;
+  return (vertices_[index]).normal;
 }
 
-const std::vector<Triangle> &Mesh::get_primitives() const {
-  return primitives_;
-};
+std::vector<Triangle> Mesh::get_primitives() const {
+  std::vector<Triangle> primitives;
+  for (const auto &idx : indices_) {
+    primitives.push_back(Triangle(vertices_, idx[0], idx[1], idx[2]));
+  }
+  return primitives;
+}
 
-std::vector<Triangle> &Mesh::get_primitives() { return primitives_; };
-
-std::shared_ptr<PhoneMaterial> &Mesh::get_material() { return material_; }
+Triangle Mesh::get_primitive(const size_t index) const {
+  assert(index >= 0 && index < indices_.size());
+  return Triangle(vertices_, indices_[index][0], indices_[index][1],
+                  indices_[index][2]);
+}
 
 const std::shared_ptr<PhoneMaterial> &Mesh::get_material() const {
   return material_;
@@ -54,19 +62,19 @@ std::vector<Mesh> Mesh::load_mesh(
   for (const auto &mesh : loader.LoadedMeshes) {
     spdlog::info("Current mesh has {} vertices.", mesh.Vertices.size());
 
-    std::vector<std::shared_ptr<Vertex>> vertices;
+    std::vector<Vertex> vertices;
     for (decltype(mesh.Vertices)::size_type i = 0; i < mesh.Vertices.size();
          i++) {
-      vertices.push_back(std::make_shared<Vertex>(
+      vertices.push_back(Vertex(
           OBJL_VEC3_TO_EIGEN_VECTOR(mesh.Vertices[i].Position),
           OBJL_VEC3_TO_EIGEN_VECTOR(mesh.Vertices[i].Normal),
           OBJL_VEC2_TO_EIGEN_VECTOR(mesh.Vertices[i].TextureCoordinate)));
     }
-    std::vector<Triangle> primitives;
+    std::vector<std::array<size_t, 3>> indices;
     for (decltype(mesh.Indices)::size_type i = 0; i < mesh.Indices.size();
          i += 3) {
-      primitives.push_back(Triangle(vertices, mesh.Indices[i],
-                                    mesh.Indices[i + 1], mesh.Indices[i + 2]));
+      indices.push_back(
+          {mesh.Indices[i], mesh.Indices[i + 1], mesh.Indices[i + 2]});
     }
 
     std::unordered_map<Texture::TextureType, std::shared_ptr<Texture>> textures;
@@ -82,7 +90,7 @@ std::vector<Mesh> Mesh::load_mesh(
     auto material = std::make_shared<PhoneMaterial>(
         textures, std::make_shared<Lamp>(Point3d{}, 16.));
 
-    res.push_back(Mesh(vertices, primitives, material));
+    res.push_back(Mesh(vertices, indices, material));
   }
   return res;
 }
diff --git a/src/mesh.h b/src/mesh.h
index 4723e72..ecb5432 100644
--- a/src/mesh.h
+++ b/src/mesh.h
@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <array>
 #include <memory>
 #include <unordered_map>
 
@@ -12,8 +13,8 @@
 
 class Mesh {
 public:
-  Mesh(const std::vector<std::shared_ptr<Vertex>> &vertices,
-       const std::vector<Triangle> &primitives,
+  Mesh(const std::vector<Vertex> &vertices,
+       const std::vector<std::array<size_t, 3>> &indices,
        const std::shared_ptr<PhoneMaterial> &phone_material);
 
   static std::vector<Mesh> load_mesh(
@@ -21,22 +22,23 @@ public:
       const std::unordered_map<Texture::TextureType, std::string> textures);
 
 public:
-  std::vector<std::shared_ptr<Vertex>>::size_type get_vertex_size() const;
+  std::vector<Vertex> &get_vertices();
+
+  std::vector<Vertex>::size_type get_vertex_size() const;
 
   const decltype(Vertex::texture_coordinate) &
   get_texture_coordinate(const unsigned int index) const;
 
   Point3d get_normal_vector(const unsigned int index) const;
 
-  const std::vector<Triangle> &get_primitives() const;
-  std::vector<Triangle> &get_primitives();
+  std::vector<Triangle> get_primitives() const;
+  Triangle get_primitive(const size_t index) const;
 
-  std::shared_ptr<PhoneMaterial> &get_material();
   const std::shared_ptr<PhoneMaterial> &get_material() const;
 
 private:
-  std::vector<std::shared_ptr<Vertex>> vertices_;
-  std::vector<Triangle> primitives_;
+  std::vector<Vertex> vertices_;
+  std::vector<std::array<size_t, 3>> indices_;
 
   std::shared_ptr<PhoneMaterial> material_;
 };
diff --git a/src/minus_renderer.cc b/src/minus_renderer.cc
index 00c172a..cd1bdf8 100644
--- a/src/minus_renderer.cc
+++ b/src/minus_renderer.cc
@@ -19,8 +19,6 @@ MinusRenderer::MinusRenderer(float near, float far, float fov,
 
 void MinusRenderer::set_meshes(const std::vector<Mesh> &meshes) {
   meshes_ = meshes;
-  spdlog::info("Mesh size: {}, the primitives size of the first mesh: {}",
-               meshes_.size(), meshes_.front().get_primitives().size());
 }
 
 float MinusRenderer::calculate_height(const float fov, const float near) {
@@ -94,35 +92,38 @@ MinusRenderer::construct_transform(const int resolution_width,
 
 std::tuple<double, double, double>
 MinusRenderer::calculate_barycentric_coordinate(const Triangle &t,
-                                                const Point2d &p) {
+                                                const Point3d &p) {
   const auto &points = t.get_vertex_position();
-  const auto &A = (points[0]).head(2);
-  const auto &B = (points[1]).head(2);
-  const auto &C = (points[2]).head(2);
-  double alpha =
-      (-(p.x() - B.x()) * (C.y() - B.y()) + (p.y() - B.y()) * (C.x() - B.x())) /
-      (-(A.x() - B.x()) * (C.y() - B.y()) + (A.y() - B.y()) * (C.x() - B.x()));
-  double beta =
-      (-(p.x() - C.x()) * (A.y() - C.y()) + (p.y() - C.y()) * (A.x() - C.x())) /
-      (-(B.x() - C.x()) * (A.y() - C.y()) + (B.y() - C.y()) * (A.x() - C.x()));
-  double gamma = 1. - alpha - beta;
+  const auto &pa = points[0];
+  const auto &pb = points[1];
+  const auto &pc = points[2];
+  const auto &triangle_normal = t.normal_vector();
+
+  const double squared_area = triangle_normal.norm() * triangle_normal.norm();
+  const double alpha =
+      (triangle_normal.dot((pc - pb).cross(p - pb))) / squared_area;
+  const double beta =
+      (triangle_normal.dot((pa - pc).cross(p - pc))) / squared_area;
+  const double gamma =
+      (triangle_normal.dot((pb - pa).cross(p - pa))) / squared_area;
+
   return {alpha, beta, gamma};
 }
 
 void MinusRenderer::model_transform(const TransformMatrix &mtx) {
   for (auto &m : meshes_) {
-    for (auto &t : m.get_primitives()) {
-      const auto &[res, _] = apply_transform(mtx, t.get_vertex_position());
-      t.set_points(res);
+    for (auto &v : m.get_vertices()) {
+      v.position = (mtx * v.position.homogeneous()).hnormalized();
+      v.normal = (mtx * v.normal.homogeneous()).hnormalized();
     }
   }
 }
 
 void MinusRenderer::view_transform(const TransformMatrix &mtx) {
   for (auto &m : meshes_) {
-    for (auto &t : m.get_primitives()) {
-      const auto &[res, _] = apply_transform(mtx, t.get_vertex_position());
-      t.set_points(res);
+    for (auto &v : m.get_vertices()) {
+      v.position = (mtx * v.position.homogeneous()).hnormalized();
+      v.normal = (mtx * v.normal.homogeneous()).hnormalized();
     }
   }
 }
@@ -133,22 +134,16 @@ cv::Mat MinusRenderer::render(const int resolution_width,
   const auto [ss_transform, inv_ss_transform] =
       construct_transform(resolution_width, resolution_height);
 
-  // 主要为了把顶点坐标拷贝一份，否则 camera space 的坐标被变换到 screen space,
-  // 下次渲染时拿到的就不是 camera space 的坐标
-  std::vector<Mesh> meshes = meshes_;
   Rasterizer rasterizer{resolution_width, resolution_height};
-  for (int mesh_index = 0; mesh_index < meshes.size(); ++mesh_index) {
-    auto &mesh = meshes[mesh_index];
-    auto &primitives = mesh.get_primitives();
-    for (int i = 0; i < primitives.size(); ++i) {
-      auto &t = primitives[i];
-      const auto &triangle_vertices = t.get_vertex_position();
-      const auto &[res, _] =
-          apply_transform(ss_transform, t.get_vertex_position());
-      t.set_points(res);
+  for (int mesh_index = 0; mesh_index < meshes_.size(); ++mesh_index) {
+    auto primitives = (meshes_[mesh_index]).get_primitives();
+    for (auto &t : primitives) {
+      t.set_points(apply_transform(ss_transform, t.get_vertex_position()));
     }
+    rasterizer.rasterize(mesh_index, primitives);
   }
-  const auto &shading_points = rasterizer.rasterize(meshes);
+
+  const auto &shading_points = rasterizer.get_shading_points();
   assert(!shading_points.empty());
   cv::Mat color_image(shading_points.size(), (shading_points[0]).size(),
                       CV_8UC3);
@@ -162,23 +157,16 @@ cv::Mat MinusRenderer::render(const int resolution_width,
       if (fragment.triangle.mesh_index >= 0 &&
           fragment.triangle.mesh_index < meshes_.size()) {
         const auto &mesh = meshes_[fragment.triangle.mesh_index];
-        const auto &primitives = mesh.get_primitives();
-        if (fragment.triangle.triangle_index >= 0 &&
-            fragment.triangle.triangle_index < primitives.size()) {
+        if (fragment.depth > -std::numeric_limits<double>::infinity()) {
           const Point3d &position =
               (inv_ss_transform *
                (Point3d{x + 0.5, y + 0.5, fragment.depth}.homogeneous()))
                   .hnormalized();
-          spdlog::trace("Screen space potions: ({}, {}, {}), camera space "
-                        "position: ({}, {}, {})",
-                        x + 0.5, y + 0.5, fragment.depth, position.x(),
-                        position.y(), position.z());
 
-          const auto &triangle = primitives[fragment.triangle.triangle_index];
+          const auto &triangle =
+              mesh.get_primitive(fragment.triangle.triangle_index);
           const auto &[alpha, beta, gamma] =
-              calculate_barycentric_coordinate(triangle, position.head(2));
-          spdlog::trace("barycentric coordinate:  ({}, {}, {})", alpha, beta,
-                        gamma);
+              calculate_barycentric_coordinate(triangle, position);
 
           std::vector<Point2d> triangle_uv;
           std::vector<Point3d> triangle_normal;
@@ -191,22 +179,18 @@ cv::Mat MinusRenderer::render(const int resolution_width,
                          gamma * triangle_uv[2].x(),
                      alpha * triangle_uv[0].y() + beta * triangle_uv[1].y() +
                          gamma * triangle_uv[2].y()};
-          spdlog::trace("UV: ({}, {}, {})", uv.x(), uv.y());
+          const auto &normal = -1. * Point3d(alpha * triangle_normal[0].x() +
+                                                 beta * triangle_normal[1].x() +
+                                                 gamma * triangle_normal[2].x(),
+                                             alpha * triangle_normal[0].y() +
+                                                 beta * triangle_normal[1].y() +
+                                                 gamma * triangle_normal[2].y(),
+                                             alpha * triangle_normal[0].z() +
+                                                 beta * triangle_normal[1].z() +
+                                                 gamma * triangle_normal[2].z())
+                                         .normalized();
 
-          const auto &normal = Point3d{alpha * triangle_normal[0].x() +
-                                           beta * triangle_normal[1].x() +
-                                           gamma * triangle_normal[2].x(),
-                                       alpha * triangle_normal[0].y() +
-                                           beta * triangle_normal[1].y() +
-                                           gamma * triangle_normal[2].y(),
-                                       alpha * triangle_normal[0].z() +
-                                           beta * triangle_normal[1].z() +
-                                           gamma * triangle_normal[2].z()}
-                                   .normalized();
-          spdlog::trace("Normal: ({}, {}, {})", normal.x(), normal.y(),
-                        normal.z());
-
-          auto &material = mesh.get_material();
+          const auto &material = mesh.get_material();
           pixel_color =
               material->shade(Vertex{position, normal, uv}, Point3d{});
         }
diff --git a/src/minus_renderer.h b/src/minus_renderer.h
index 95554b3..4dd2d6d 100644
--- a/src/minus_renderer.h
+++ b/src/minus_renderer.h
@@ -24,7 +24,7 @@ private:
   static float calculate_height(const float fov, const float near);
   static float calculate_width(const float height, const float ratio);
   static std::tuple<double, double, double>
-  calculate_barycentric_coordinate(const Triangle &t, const Point2d &p);
+  calculate_barycentric_coordinate(const Triangle &t, const Point3d &p);
 
 private:
   std::pair<TransformMatrix, TransformMatrix>
diff --git a/src/phone_material.cc b/src/phone_material.cc
index b40624d..770093d 100644
--- a/src/phone_material.cc
+++ b/src/phone_material.cc
@@ -10,19 +10,19 @@ PhoneMaterial::PhoneMaterial(
     const std::unordered_map<Texture::TextureType, std::shared_ptr<Texture>>
         &textures,
     const std::shared_ptr<Lamp> &lamp)
-    : point_lamp_(lamp), textures_(textures), Ka(cv::Vec3b{32, 32, 32}),
-      Ks(cv::Vec3b(64, 64, 64)),
+    : point_lamp_(lamp), textures_(textures), Ka(cv::Vec3b{24, 24, 24}),
+      Ks(cv::Vec3b(48, 48, 48)),
       specular_attenuation_factor_(defaultAttenuationFactor) {
   spdlog::info("Specular attenuation factor: {}", specular_attenuation_factor_);
 }
 
 cv::Vec3b PhoneMaterial::shade(const Vertex &shading_point,
-                               const Point3d &view_point) {
+                               const Point3d &view_point) const {
   cv::Vec3b shading_res{0, 0, 0};
 
   // Diffuse
   assert(textures_.find(Texture::DiffuseMap) != textures_.end());
-  const auto &diffuse_map = textures_[Texture::DiffuseMap];
+  const auto &diffuse_map = textures_.at(Texture::DiffuseMap);
   const auto &Kd = diffuse_map->sample(shading_point.texture_coordinate);
 
   const auto &point2light_vector =
diff --git a/src/phone_material.h b/src/phone_material.h
index 768284a..d7532a2 100644
--- a/src/phone_material.h
+++ b/src/phone_material.h
@@ -17,10 +17,10 @@ public:
                                          std::shared_ptr<Texture>> &textures,
                 const std::shared_ptr<Lamp> &lamp);
 
-  cv::Vec3b shade(const Vertex &shading_point, const Point3d &view_point);
+  cv::Vec3b shade(const Vertex &shading_point, const Point3d &view_point) const;
 
 private:
-  static constexpr int defaultAttenuationFactor = 16;
+  static constexpr int defaultAttenuationFactor = 12;
 
 private:
   std::shared_ptr<Lamp> point_lamp_;
diff --git a/src/rasterizer.cc b/src/rasterizer.cc
index eef104b..7db233d 100644
--- a/src/rasterizer.cc
+++ b/src/rasterizer.cc
@@ -13,34 +13,29 @@ Rasterizer::Rasterizer(const int width, const int height)
       shading_points_(std::vector<std::vector<RasterizerResult>>(
           height, std::vector<RasterizerResult>(width, RasterizerResult{}))) {}
 
-std::vector<std::vector<RasterizerResult>>
-Rasterizer::rasterize(const std::vector<Mesh> &meshes) {
-  for (int m_id = 0; m_id < meshes.size(); ++m_id) {
-    const auto &primitives = (meshes[m_id]).get_primitives();
-
-    const int thread_num = 8;
-    std::vector<std::thread> rasterize_threads;
-    for (int begin = 0, offset = primitives.size() / thread_num,
-             remainer = (primitives.size() % thread_num);
-         begin < primitives.size();) {
-      int end = begin + offset;
-      if (remainer > 0) {
-        end += 1;
-        remainer -= 1;
-      }
-      rasterize_threads.push_back(std::thread(
-          [this, m_id](const std::vector<Triangle> &primitives, const int begin,
-                       const int end) {
-            this->rasterize(m_id, primitives, begin, end);
-          },
-          (meshes[m_id]).get_primitives(), begin, end));
-      begin = end;
-    }
-    for (auto &t : rasterize_threads) {
-      t.join();
+void Rasterizer::rasterize(const int mesh_idx,
+                           const std::vector<Triangle> &primitives) {
+  const int thread_num = 8;
+  std::vector<std::thread> rasterize_threads;
+  for (int begin = 0, offset = primitives.size() / thread_num,
+           remainer = (primitives.size() % thread_num);
+       begin < primitives.size();) {
+    int end = begin + offset;
+    if (remainer > 0) {
+      end += 1;
+      remainer -= 1;
     }
+    rasterize_threads.push_back(std::thread(
+        [this, mesh_idx](const std::vector<Triangle> &primitives,
+                         const int begin, const int end) {
+          this->rasterize(mesh_idx, primitives, begin, end);
+        },
+        primitives, begin, end));
+    begin = end;
+  }
+  for (auto &t : rasterize_threads) {
+    t.join();
   }
-  return shading_points_;
 }
 
 void Rasterizer::rasterize(const int mesh_idx,
@@ -71,6 +66,11 @@ void Rasterizer::rasterize(const int mesh_idx,
   }
 }
 
+const std::vector<std::vector<RasterizerResult>> &
+Rasterizer::get_shading_points() const {
+  return shading_points_;
+}
+
 void Rasterizer::reset() {
   shading_points_ = std::vector<std::vector<RasterizerResult>>(
       height_, std::vector<RasterizerResult>(width_, RasterizerResult{}));
@@ -80,7 +80,7 @@ std::pair<bool, double> Rasterizer::inside(const Point2d &p_screen,
                                            const Triangle &t) {
   const auto points = t.get_vertex_position();
 
-  const auto plane_normal = t.normal_vector();
+  const auto plane_normal = t.unit_normal_vector();
   const auto plane_point = points[0];
   const auto z_screen =
       plane_point.z() - (plane_normal.x() * (p_screen.x() - plane_point.x()) +
diff --git a/src/rasterizer.h b/src/rasterizer.h
index 4a97e25..d21cd00 100644
--- a/src/rasterizer.h
+++ b/src/rasterizer.h
@@ -21,9 +21,9 @@ public:
   Rasterizer(const int width, const int height);
 
 public:
-  std::vector<std::vector<RasterizerResult>>
-  rasterize(const std::vector<Mesh> &meshes);
+  void rasterize(const int mesh_idx, const std::vector<Triangle> &primitives);
 
+  const std::vector<std::vector<RasterizerResult>> &get_shading_points() const;
   void reset();
 
 private:
diff --git a/src/triangle.cc b/src/triangle.cc
index d71a6e8..ce2a429 100644
--- a/src/triangle.cc
+++ b/src/triangle.cc
@@ -9,11 +9,11 @@ Triangle::Triangle(const Point3d &a, unsigned int idx_a, const Point3d &b,
                    unsigned int idx_b, const Point3d &c, unsigned int idx_c)
     : indices_({idx_a, idx_b, idx_c}), vertices_({a, b, c}) {}
 
-Triangle::Triangle(const std::vector<std::shared_ptr<Vertex>> &vertices,
-                   unsigned int idx_a, unsigned int idx_b, unsigned int idx_c)
+Triangle::Triangle(const std::vector<Vertex> &vertices, unsigned int idx_a,
+                   unsigned int idx_b, unsigned int idx_c)
     : indices_({idx_a, idx_b, idx_c}),
-      vertices_({(vertices[idx_a])->position, (vertices[idx_b])->position,
-                 (vertices[idx_c])->position}) {}
+      vertices_({(vertices[idx_a]).position, (vertices[idx_b]).position,
+                 (vertices[idx_c]).position}) {}
 
 std::vector<unsigned int> Triangle::get_vertex_index() const {
   return {indices_[0], indices_[1], indices_[2]};
@@ -45,8 +45,12 @@ BBox Triangle::axis_align_bbox() const {
   return BBox{x_min, y_min, (x_max - x_min + 1), (y_max - y_min + 1)};
 }
 
+Vector3d Triangle::unit_normal_vector() const {
+  return normal_vector().normalized();
+}
+
 Vector3d Triangle::normal_vector() const {
   const auto v1 = vertices_[1] - vertices_[0];
   const auto v2 = vertices_[2] - vertices_[1];
-  return v1.cross(v2).normalized();
+  return v1.cross(v2);
 }
diff --git a/src/triangle.h b/src/triangle.h
index 7c291a6..4fc4cbf 100644
--- a/src/triangle.h
+++ b/src/triangle.h
@@ -11,8 +11,8 @@ class Triangle {
 public:
   Triangle(const Point3d &a, unsigned int idx_a, const Point3d &b,
            unsigned int idx_b, const Point3d &c, unsigned int idx_c);
-  Triangle(const std::vector<std::shared_ptr<Vertex>> &vertices,
-           unsigned int idx_a, unsigned int idx_b, unsigned int idx_c);
+  Triangle(const std::vector<Vertex> &vertices, unsigned int idx_a,
+           unsigned int idx_b, unsigned int idx_c);
 
 public:
   std::vector<unsigned int> get_vertex_index() const;
@@ -22,6 +22,7 @@ public:
 public:
   BBox axis_align_bbox() const;
   Vector3d normal_vector() const;
+  Vector3d unit_normal_vector() const;
 
 private:
   std::array<unsigned int, 3> indices_;
diff --git a/src/util/math_util.h b/src/util/math_util.h
index 83cc57c..f52b250 100644
--- a/src/util/math_util.h
+++ b/src/util/math_util.h
@@ -11,14 +11,21 @@ bool fequal(const FloatType a, const FloatType b) {
 }
 
 template <int d>
-std::pair<std::vector<Eigen::Vector<double, d>>, std::vector<double>>
+std::vector<Eigen::Vector<double, d>>
 apply_transform(const TransformMatrix &mtx,
                 const std::vector<Eigen::Vector<double, d>> &points) {
-  std::pair<std::vector<Eigen::Vector<double, d>>, std::vector<double>> res{};
+  std::vector<Eigen::Vector<double, d>> res{};
   for (const auto &p : points) {
     const auto &transform_res = mtx * p.homogeneous();
-    res.first.push_back(transform_res.hnormalized());
-    res.second.push_back(transform_res.w());
+    res.push_back(transform_res.hnormalized());
   }
   return res;
 }
+
+template <int d>
+void apply_transform_in_place(const TransformMatrix &mtx,
+                              std::vector<Eigen::Vector<double, d>> &points) {
+  for (auto &p : points) {
+    p = mtx * p.homogeneous().hnormalized();
+  }
+}