diff --git a/src/Geometry.cc b/src/Geometry.cc
index 0a29ab8..6b544c4 100644
--- a/src/Geometry.cc
+++ b/src/Geometry.cc
@@ -3,22 +3,23 @@
 #include <Eigen/Dense>
 #include <cmath>
 
-Vector3f Geometry::diffuse() const { return cd; }
-Vector3f Geometry::specular() const { return cs; }
-Vector3f Geometry::ambient() const { return ca; }
-float Geometry::coefDiffuse() const { return kd; }
-float Geometry::coefSpecular() const { return ks; }
-float Geometry::coefAmbient() const { return ka; }
-float Geometry::getPhong() const { return phong; }
+Vector3f Geometry::cd() const { return cd_; }
+Vector3f Geometry::cs() const { return cs_; }
+Vector3f Geometry::ca() const { return ca_; }
+float Geometry::kd() const { return kd_; }
+float Geometry::ks() const { return ks_; }
+float Geometry::ka() const { return ka_; }
+float Geometry::phong() const { return phong_; }
+Geometry::Type Geometry::type() const { return type_; }
 
 void Geometry::setTransform(const Matrix4f &transform) {
   this->transform = transform;
 }
 
 Optional<float> Sphere::intersect(const Ray &r) const {
-  Vector3f originCenter = r.getOrigin() - center;
-  float a = r.getDirection().dot(r.getDirection());
-  float b = 2.0f * originCenter.dot(r.getDirection());
+  Vector3f originCenter = r.origin() - center;
+  float a = r.direction().dot(r.direction());
+  float b = 2.0f * originCenter.dot(r.direction());
   float c = originCenter.dot(originCenter) - radius * radius;
 
   float delta = b * b - 4 * a * c;
@@ -35,7 +36,7 @@ Optional<float> Sphere::intersect(const Ray &r) const {
   return Optional<float>::nullopt;
 }
 
-Vector3f Sphere::getNormal(const Vector3f &p) const {
+Vector3f Sphere::normal(const Vector3f &p) const {
   return (p - center).normalized();
 }
 
@@ -51,18 +52,18 @@ bool isInRectangle(const Vector3f &p, const Vector3f &a, const Vector3f &b,
 }
 
 Optional<float> Rectangle::intersect(const Ray &r) const {
-  float denom = normal.dot(r.getDirection());
+  float denom = normal_.dot(r.direction());
   if (abs(denom) < 1e-6f)
     return Optional<float>::nullopt;
 
-  float t = -normal.dot(r.getOrigin() - p1) / denom;
+  float t = -normal_.dot(r.origin() - p1) / denom;
   if (t <= 0)
     return Optional<float>::nullopt;
 
-  Vector3f p = r.getOrigin() + t * r.getDirection();
+  Vector3f p = r.origin() + t * r.direction();
 
-  return isInRectangle(p, p1, p2, p3, p4, normal) ? Optional<float>(t)
-                                                  : Optional<float>::nullopt;
+  return isInRectangle(p, p1, p2, p3, p4, normal_) ? Optional<float>(t)
+                                                   : Optional<float>::nullopt;
 }
 
-Vector3f Rectangle::getNormal(const Vector3f &p) const { return normal; }
+Vector3f Rectangle::normal(const Vector3f &p) const { return normal_; }
diff --git a/src/Geometry.h b/src/Geometry.h
index b3d1eee..2b8c947 100644
--- a/src/Geometry.h
+++ b/src/Geometry.h
@@ -19,27 +19,29 @@ public:
 
   virtual ~Geometry() = default;
   virtual Optional<float> intersect(const Ray &) const = 0;
-  virtual Vector3f getNormal(const Vector3f &) const = 0;
+  virtual Vector3f normal(const Vector3f &) const = 0;
 
 protected:
   Geometry(Type type, float ka, float kd, float ks, const Vector3f &ca,
            const Vector3f &cd, const Vector3f &cs, float pc)
-      : type(type), ka(ka), kd(kd), ks(ks), ca(ca), cd(cd), cs(cs), phong(pc) {}
+      : type_(type), ka_(ka), kd_(kd), ks_(ks), ca_(ca), cd_(cd), cs_(cs),
+        phong_(pc) {}
 
-  Type type;
-  float ka, kd, ks;    // coefficients for ambient, diffuse and specular
-  Vector3f ca, cd, cs; // ambient, diffuse and specular reflection color
-  float phong;         // phone coefficient, for `pc`
+  Type type_;
+  float ka_, kd_, ks_;    // coefficients for ambient, diffuse and specular
+  Vector3f ca_, cd_, cs_; // ambient, diffuse and specular reflection color
+  float phong_;           // phone coefficient, for `pc`
   Matrix4f transform = Matrix4f::Identity();
 
 public:
-  Vector3f diffuse() const;
-  Vector3f specular() const;
-  Vector3f ambient() const;
-  float coefDiffuse() const;
-  float coefSpecular() const;
-  float coefAmbient() const;
-  float getPhong() const;
+  Vector3f cd() const;
+  Vector3f cs() const;
+  Vector3f ca() const;
+  float kd() const;
+  float ks() const;
+  float ka() const;
+  float phong() const;
+  Type type() const;
   void setTransform(const Matrix4f &);
 };
 
@@ -51,7 +53,7 @@ public:
         center(center) {}
 
   Optional<float> intersect(const Ray &) const override;
-  Vector3f getNormal(const Vector3f &) const override;
+  Vector3f normal(const Vector3f &) const override;
 
 private:
   float radius;
@@ -64,14 +66,14 @@ public:
             const Vector3f &cs, float pc, const Vector3f &p1,
             const Vector3f &p2, const Vector3f &p3, const Vector3f &p4)
       : Geometry(Type::RECTANGLE, ka, kd, ks, ca, cd, cs, pc), p1(p1), p2(p2),
-        p3(p3), p4(p4), normal((p2 - p1).cross(p3 - p1).normalized()) {}
+        p3(p3), p4(p4), normal_((p2 - p1).cross(p3 - p1).normalized()) {}
 
   Optional<float> intersect(const Ray &) const override;
-  Vector3f getNormal(const Vector3f &) const override;
+  Vector3f normal(const Vector3f &) const override;
 
 private:
   Vector3f p1, p2, p3, p4;
-  Vector3f normal;
+  Vector3f normal_;
 };
 
 #endif // !GEOMETRY_H_
diff --git a/src/HitRecord.cc b/src/HitRecord.cc
index 6a07ee7..261e449 100644
--- a/src/HitRecord.cc
+++ b/src/HitRecord.cc
@@ -4,16 +4,16 @@ bool HitRecord::operator<(const HitRecord &other) const {
   return this->t > other.t; // to get the nearest t
 }
 
-Geometry *HitRecord::geometry() const { return g; }
+Geometry *HitRecord::geometry() const { return geometry_; }
 
-Vector3f HitRecord::getPoint() const {
-  return r.getOrigin() + t * r.getDirection();
+Vector3f HitRecord::point() const {
+  return ray_.origin() + t * ray_.direction();
 }
 
 Vector3f HitRecord::viewDirection() const {
-  return -r.getDirection().normalized();
+  return -ray_.direction().normalized();
 }
 
-Vector3f HitRecord::normal() const { return n; }
+Vector3f HitRecord::normal() const { return normal_; }
 
-void HitRecord::calcNormal() { n = g->getNormal(getPoint()); }
+void HitRecord::calcNormal() { normal_ = geometry_->normal(point()); }
diff --git a/src/HitRecord.h b/src/HitRecord.h
index c7fad17..599db5a 100644
--- a/src/HitRecord.h
+++ b/src/HitRecord.h
@@ -9,18 +9,18 @@ using Eigen::Vector3f;
 
 class HitRecord {
 public:
-  HitRecord(float t, const Ray &r, Geometry *g) : t(t), r(r), g(g) {}
+  HitRecord(float t, const Ray &r, Geometry *g) : t(t), ray_(r), geometry_(g) {}
   bool operator<(const HitRecord &) const;
 
 private:
   float t;
-  Ray r;
-  Vector3f n;
-  Geometry *g;
+  Ray ray_;
+  Vector3f normal_;
+  Geometry *geometry_;
 
 public:
   Geometry *geometry() const;
-  Vector3f getPoint() const;
+  Vector3f point() const;
   Vector3f viewDirection() const;
   Vector3f normal() const;
   void calcNormal();
diff --git a/src/Light.cc b/src/Light.cc
index 2b0030a..a23cd0c 100644
--- a/src/Light.cc
+++ b/src/Light.cc
@@ -1,4 +1,6 @@
 #include "Light.h"
+#include "Scene.h"
+
 #include <algorithm>
 #include <cmath>
 
@@ -12,34 +14,34 @@ void Light::setUseCenter(bool useCenter) { this->useCenter = useCenter; }
 
 void Light::setIsUse(bool isUse) { this->use = isUse; }
 
-Vector3f Light::getDiffuse() const { return diffuse; }
+Vector3f Light::id() const { return id_; }
 
-Vector3f Light::getSpecular() const { return specular; }
+Vector3f Light::is() const { return is_; }
 
 bool Light::isUse() const { return use; }
 
 Vector3f PointLight::illumination(const HitRecord &hit,
                                   const vector<Geometry *> &geometries) const {
-  Vector3f shadingPoint = hit.getPoint();
+  Vector3f shadingPoint = hit.point();
   Vector3f rayDirection = (center - shadingPoint).normalized();
   Geometry *geometry = hit.geometry();
   Ray shadowRay(shadingPoint, rayDirection);
 
   for (auto g : geometries)
-    if (g != geometry && g->intersect(shadowRay).hasValue())
+    if (g != geometry && g->intersect(shadowRay).hasValue() &&
+        g->type() == Geometry::Type::SPHERE)
       return Vector3f::Zero();
 
-  Vector3f ambient_ = geometry->coefAmbient() * geometry->ambient();
+  Vector3f ambient_ =
+      geometry->ka() * geometry->ca().array() * Scene::current->ai().array();
 
-  Vector3f diffuse_ = geometry->coefDiffuse() * geometry->diffuse().array() *
-                      diffuse.array() *
+  Vector3f diffuse_ = geometry->kd() * geometry->cd().array() * id_.array() *
                       std::max(0.0f, hit.normal().dot(rayDirection));
 
   Vector3f halfWay = (hit.viewDirection() + rayDirection).normalized();
   Vector3f specular_ =
-      geometry->coefSpecular() * geometry->specular().array() *
-      specular.array() *
-      pow(std::max(0.0f, hit.normal().dot(halfWay)), geometry->getPhong());
+      geometry->ks() * geometry->cs().array() * is_.array() *
+      pow(std::max(0.0f, hit.normal().dot(halfWay)), geometry->phong());
 
   return specular_ + ambient_ + diffuse_;
 }
@@ -55,9 +57,12 @@ Vector3f AreaLight::illumination(const HitRecord &hit,
     color += PointLight(*this, p1 + (u + v) / 2).illumination(hit, geometries);
   } else {
     for (int y = 0; y < gridSize; ++y)
-      for (int x = 0; x < gridSize; ++x)
-        color += PointLight(*this, p1 + (u * x + v * y) / gridSize)
-                     .illumination(hit, geometries);
+      for (int x = 0; x < gridSize; ++x) {
+        Vector3f contribution =
+            PointLight(*this, p1 + (u * x + v * y) / gridSize)
+                .illumination(hit, geometries);
+        color += contribution;
+      }
   }
 
   return color / gridSize / gridSize;
diff --git a/src/Light.h b/src/Light.h
index 60afbce..7f21867 100644
--- a/src/Light.h
+++ b/src/Light.h
@@ -21,11 +21,11 @@ public:
 
 protected:
   Light(Type type, const Vector3f &id, const Vector3f &is)
-      : type(type), diffuse(id), specular(is) {}
+      : type_(type), id_(id), is_(is) {}
 
-  Type type;
-  Vector3f diffuse;
-  Vector3f specular;
+  Type type_;
+  Vector3f id_;
+  Vector3f is_;
   Matrix4f transform = Matrix4f::Identity(); // optional member `transform`
   unsigned int gridSize = 0;                 // optional member `n`
   bool useCenter = false;                    // optional member `usecenter`
@@ -36,8 +36,8 @@ public:
   void setGridSize(unsigned int);
   void setUseCenter(bool);
   void setIsUse(bool);
-  Vector3f getDiffuse() const;
-  Vector3f getSpecular() const;
+  Vector3f id() const;
+  Vector3f is() const;
   bool isUse() const;
 };
 
@@ -60,7 +60,7 @@ public:
       : Light(Type::Point, id, is), center(center) {}
 
   PointLight(const AreaLight &al, const Vector3f &center)
-      : PointLight(al.getDiffuse(), al.getSpecular(), center) {}
+      : PointLight(al.id(), al.is(), center) {}
 
   virtual Vector3f illumination(const HitRecord &,
                                 const vector<Geometry *> &) const override;
diff --git a/src/Output.cc b/src/Output.cc
index 840212b..222e585 100644
--- a/src/Output.cc
+++ b/src/Output.cc
@@ -2,6 +2,8 @@
 
 #include <fstream>
 
+Output *Output::current = nullptr;
+
 void Output::write() {
   std::ofstream fout(path, std::ios_base::out | std::ios_base::binary);
   fout << "P6\n" << width << ' ' << height << '\n' << "255" << std::endl;
diff --git a/src/Output.h b/src/Output.h
index d7a065d..8cf7b9c 100644
--- a/src/Output.h
+++ b/src/Output.h
@@ -33,6 +33,8 @@ public:
   float g(int) const;
   void b(int, float);
   float b(int) const;
+
+  static Output *current;
 };
 
 #endif // !OUTPUT_H_
diff --git a/src/Ray.cc b/src/Ray.cc
index 4cafd1d..fddd2f5 100644
--- a/src/Ray.cc
+++ b/src/Ray.cc
@@ -1,5 +1,5 @@
 #include "Ray.h"
 
-Vector3f Ray::getOrigin() const { return origin; }
+Vector3f Ray::origin() const { return origin_; }
 
-Vector3f Ray::getDirection() const { return direction; }
+Vector3f Ray::direction() const { return direction_; }
diff --git a/src/Ray.h b/src/Ray.h
index 9fe5b37..a344e5d 100644
--- a/src/Ray.h
+++ b/src/Ray.h
@@ -7,15 +7,15 @@ using Eigen::Vector3f;
 
 class Ray {
 public:
-  Ray(const Vector3f &o, const Vector3f &d) : origin(o), direction(d) {}
+  Ray(const Vector3f &o, const Vector3f &d) : origin_(o), direction_(d) {}
 
 private:
-  Vector3f origin;
-  Vector3f direction;
+  Vector3f origin_;
+  Vector3f direction_;
 
 public:
-  Vector3f getOrigin() const;
-  Vector3f getDirection() const;
+  Vector3f origin() const;
+  Vector3f direction() const;
 };
 
 #endif // !RAY_H_
diff --git a/src/RayTracer.cc b/src/RayTracer.cc
index c79add8..1209fae 100644
--- a/src/RayTracer.cc
+++ b/src/RayTracer.cc
@@ -27,27 +27,25 @@ Ray getRay(int x, int y, const Vector3f &camPos, const Vector3f &pxUpperLeft,
   return Ray(camPos, pxUpperLeft + x * du + y * dv - camPos);
 }
 
-void RayTracer::calculateColor(const HitRecord &hit, Output *buffer, int i) {
-  buffer->r(i, 0);
-  buffer->g(i, 0);
-  buffer->b(i, 0);
+void RayTracer::calculateColor(const HitRecord &hit, int i) {
+  Vector3f result(0, 0, 0);
   for (auto light : lights)
-    if (light->isUse()) {
-      Vector3f contribution =
-          light->illumination(hit, geometries).cwiseMax(0.0f).cwiseMin(1.0f) /
-          lights.size();
-      buffer->r(i, buffer->r(i) + contribution.x());
-      buffer->g(i, buffer->g(i) + contribution.y());
-      buffer->b(i, buffer->b(i) + contribution.z());
-    }
+    result += light->isUse() ? light->illumination(hit, geometries)
+                             : Vector3f::Zero();
+
+  result = result.cwiseMax(0.0f).cwiseMin(1.0f);
+  Output::current->r(i, result.x());
+  Output::current->g(i, result.y());
+  Output::current->b(i, result.z());
 }
 
-void RayTracer::render(Scene *scene) {
-  int width = scene->getWidth();
-  int height = scene->getHeight();
-  Vector3f cameraPos = scene->getCenter();
-  Vector3f lookAt = scene->getLookAt();
-  float vpHeight = 2 * tan(scene->getFov() / 180 * M_PI / 2) * lookAt.norm();
+void RayTracer::render() {
+  int width = Scene::current->width();
+  int height = Scene::current->height();
+  Vector3f cameraPos = Scene::current->center();
+  Vector3f lookAt = Scene::current->lookAt();
+  float vpHeight =
+      2 * tan(Scene ::current->fov() / 180 * M_PI / 2) * lookAt.norm();
   float vpWidth = vpHeight * width / height;
   Vector3f vpU = Vector3f(vpWidth, 0, 0);
   Vector3f vpV = Vector3f(0, -vpHeight, 0);
@@ -57,8 +55,8 @@ void RayTracer::render(Scene *scene) {
   Vector3f vpUpperLeft = cameraPos + lookAt - vpU / 2.0 - vpV / 2.0;
   Vector3f pxUpperLeft = vpUpperLeft + (du + dv) / 2.0;
 
-  Output *buffer =
-      new Output(scene->getBackgroundColor(), scene->getName(), width, height);
+  Output::current = new Output(Scene::current->backgroundColor(),
+                               Scene::current->name(), width, height);
 
   for (int y = 0; y < height; ++y)
     for (int x = 0; x < width; ++x) {
@@ -73,11 +71,9 @@ void RayTracer::render(Scene *scene) {
       if (!records.empty()) {
         HitRecord hit = records.top();
         hit.calcNormal();
-        calculateColor(hit, buffer, y * width + x);
+        calculateColor(hit, y * width + x);
       }
     }
-
-  outputs.push_back(buffer);
 }
 
 void RayTracer::output() {
@@ -88,8 +84,9 @@ void RayTracer::output() {
 void RayTracer::run() {
   parse();
 
-  for (auto scene : scenes)
-    render(scene);
-
-  output();
+  for (auto scene : scenes) {
+    Scene::current = scene;
+    render();
+    Output::current->write();
+  }
 }
diff --git a/src/RayTracer.h b/src/RayTracer.h
index 43a9075..764bd05 100644
--- a/src/RayTracer.h
+++ b/src/RayTracer.h
@@ -22,8 +22,8 @@ private:
   std::vector<Output *> outputs;
 
   void parse();
-  void calculateColor(const HitRecord &, Output *, int);
-  void render(Scene *);
+  void calculateColor(const HitRecord &, int);
+  void render();
   void output();
 };
 
diff --git a/src/Scene.cc b/src/Scene.cc
index 9c48128..f9d9840 100644
--- a/src/Scene.cc
+++ b/src/Scene.cc
@@ -1,33 +1,37 @@
 #include "Scene.h"
 
-string Scene::getName() const { return name; }
+Scene *Scene::current = nullptr;
 
-int Scene::getWidth() { return width; }
+string Scene::name() const { return name_; }
 
-int Scene::getHeight() { return height; }
+int Scene::width() { return width_; }
 
-float Scene::getFov() { return fov; }
+int Scene::height() { return height_; }
 
-Vector3f Scene::getCenter() const { return center; }
+float Scene::fov() { return fov_; }
 
-Vector3f Scene::getUpVector() const { return up; }
+Vector3f Scene::ai() const { return ai_; }
 
-Vector3f Scene::getLookAt() const { return lookAt; }
+Vector3f Scene::center() const { return center_; }
 
-Vector3f Scene::getBackgroundColor() const { return backgroundColor; }
+Vector3f Scene::up() const { return up_; }
+
+Vector3f Scene::lookAt() const { return lookAt_; }
+
+Vector3f Scene::backgroundColor() const { return bgc_; }
 
 void Scene::setRaysPerPixel(const Eigen::VectorXi &raysPerPixel) {
-  this->raysPerPixel = raysPerPixel;
+  this->raysPerPixel_ = raysPerPixel;
 }
 
 void Scene::setAntialiasing(bool antialiasing) {
-  this->antialiasing = antialiasing;
+  this->antialiasing_ = antialiasing;
 }
 
 void Scene::setTwoSideRender(bool twoSideRender) {
-  this->twoSideRender = twoSideRender;
+  this->twoSideRender_ = twoSideRender;
 }
 
 void Scene::setGlobalIllum(bool globalIllum) {
-  this->globalIllum = globalIllum;
+  this->globalIllum_ = globalIllum;
 }
diff --git a/src/Scene.h b/src/Scene.h
index 8ac10e0..6775ac2 100644
--- a/src/Scene.h
+++ b/src/Scene.h
@@ -12,38 +12,40 @@ public:
   Scene(string name, int width, int height, float fov, const Vector3f &center,
         const Vector3f &up, const Vector3f &lookAt, const Vector3f &ai,
         const Vector3f &bgc)
-      : name(name), width(width), height(height), fov(fov), center(center),
-        up(up), lookAt(lookAt), ai(ai), backgroundColor(bgc) {}
+      : name_(name), width_(width), height_(height), fov_(fov), center_(center),
+        up_(up), lookAt_(lookAt), ai_(ai), bgc_(bgc) {}
 
 private:
-  string name;
-  int width;
-  int height;
-  float fov;
-  Vector3f center;
-  Vector3f up;
-  Vector3f lookAt;
-  Vector3f ai; // ambient intensity
-  Vector3f backgroundColor;
+  string name_;
+  int width_;
+  int height_;
+  float fov_;
+  Vector3f center_;
+  Vector3f up_;
+  Vector3f lookAt_;
+  Vector3f ai_; // ambient intensity
+  Vector3f bgc_;
 
-  Eigen::VectorXi raysPerPixel;
-  bool antialiasing = false;
-  bool twoSideRender = false;
-  bool globalIllum = false;
+  Eigen::VectorXi raysPerPixel_;
+  bool antialiasing_ = false;
+  bool twoSideRender_ = false;
+  bool globalIllum_ = false;
 
 public:
-  string getName() const;
-  int getWidth();
-  int getHeight();
-  float getFov();
-  Vector3f getCenter() const;
-  Vector3f getUpVector() const;
-  Vector3f getLookAt() const;
-  Vector3f getBackgroundColor() const;
+  string name() const;
+  int width();
+  int height();
+  float fov();
+  Vector3f ai() const;
+  Vector3f center() const;
+  Vector3f up() const;
+  Vector3f lookAt() const;
+  Vector3f backgroundColor() const;
   void setRaysPerPixel(const Eigen::VectorXi &);
   void setAntialiasing(bool);
   void setTwoSideRender(bool);
   void setGlobalIllum(bool);
+  static Scene *current;
 };
 
 #endif // !SCENE_H_