Implement Multi-Sample Anti Aliasing (MSAA)

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "src/assimp"]
+	path = src/assimp
+	url = git@github.com:assimp/assimp

models/suzanne/suzanne.mtl

@@ -0,0 +1,12 @@
+# Blender 4.3.2 MTL File: 'None'
+# www.blender.org
+
+newmtl Material
+Ka 1.000000 1.000000 1.000000
+Ks 0.500000 0.500000 0.500000
+Ke 0.000000 0.000000 0.000000
+Ni 1.450000
+d 1.000000
+illum 2
+map_Kd diffuse.png
+map_Ks specular.png

shaders/frag.glsl

@@ -3,8 +3,8 @@
 #define POINT_LIGHT_COUNT 4
 
 struct Material {
-  sampler2D diffuse;
+  sampler2D diffuse1;
-  sampler2D specular;
+  sampler2D specular1;
   float shininess;
 };
 
@@ -35,33 +35,40 @@ struct SpotLight {
   float outer_cutoff;
 };
 
-in vec3 vert_normal;
+in VS_OUT {
-in vec3 frag_position;
+  vec3 vert_normal;
-in vec2 uv_coords;
+  vec3 frag_position;
-
+  vec2 uv_coords;
-out vec4 color;
+} fs_in;
 
 uniform Material material;
 uniform DirLight directional_light;
 uniform PointLight point_lights[POINT_LIGHT_COUNT];
 uniform SpotLight spot_light;
-uniform vec3 camera_position;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
 
 vec3 calc_dir_light(DirLight light, vec3 normal, vec3 view_direction);
 vec3 calc_point_light(PointLight light, vec3 normal, vec3 frag_position, vec3 view_direction);
 vec3 calc_spot_light(SpotLight light, vec3 normal, vec3 frag_position, vec3 view_direction);
 
+out vec4 color;
+
 void main() {
-  vec3  normal         = normalize(vert_normal);
+  vec3  normal         = normalize(fs_in.vert_normal);
-  vec3  view_direction = normalize(camera_position - frag_position);
+  vec3  view_direction = normalize(fs_in.frag_position - camera_position);
 
   vec3 result = calc_dir_light(directional_light, normal, view_direction);
 
   for (int i = 0; i < POINT_LIGHT_COUNT; ++i) {
-    result += calc_point_light(point_lights[i], normal, frag_position, view_direction);
+    result += calc_point_light(point_lights[i], normal, fs_in.frag_position, view_direction);
   }
 
-  result += calc_spot_light(spot_light, normal, frag_position, view_direction);
+  result += calc_spot_light(spot_light, normal, fs_in.frag_position, view_direction);
 
   color = vec4(result, 1.0);
 };
@@ -70,11 +77,11 @@ vec3 calc_dir_light(DirLight light, vec3 normal, vec3 view_direction) {
   vec3 light_direction     = normalize(-light.direction);
   vec3  reflect_direction  = reflect(-light_direction, normal);
   float diff               = max(dot(normal, light_direction), 0.0);
-  vec3  diff_tex           = vec3(texture(material.diffuse, uv_coords));
+  vec3  diff_tex           = vec3(texture(material.diffuse1, fs_in.uv_coords));
   float spec               = pow(max(dot(reflect_direction, view_direction), 0.0), material.shininess);
   vec3  ambient            = light.ambient * diff_tex;
   vec3  diffuse            = light.diffuse * (diff * diff_tex);
-  vec3  specular           = light.specular * (spec * vec3(texture(material.specular, uv_coords)));
+  vec3  specular           = light.specular * (spec * vec3(texture(material.specular1, fs_in.uv_coords)));
 
   return ambient + diffuse + specular;
 }
@@ -85,11 +92,11 @@ vec3 calc_point_light(PointLight light, vec3 normal, vec3 frag_position, vec3 vi
   float distance           = length(light.position - frag_position);
   float attenuation        = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));
   float diff               = max(dot(normal, light_direction), 0.0);
-  vec3  diff_tex           = vec3(texture(material.diffuse, uv_coords));
+  vec3  diff_tex           = vec3(texture(material.diffuse1, fs_in.uv_coords));
   float spec               = pow(max(dot(reflect_direction, view_direction), 0.0), material.shininess);
   vec3  ambient            = light.ambient * diff_tex * attenuation;
   vec3  diffuse            = light.diffuse * (diff * diff_tex) * attenuation;
-  vec3  specular           = light.specular * (spec * vec3(texture(material.specular, uv_coords))) * attenuation;
+  vec3  specular           = light.specular * (spec * vec3(texture(material.specular1, fs_in.uv_coords))) * attenuation;
 
   return ambient + diffuse + specular;
 }
@@ -102,10 +109,10 @@ vec3 calc_spot_light(SpotLight light, vec3 normal, vec3 frag_position, vec3 view
   float intensity          = clamp((theta - light.outer_cutoff) / epsilon, 0.0, 1.0);
   float diff               = max(dot(normal, light_direction), 0.0);
   float spec               = pow(max(dot(reflect_direction, view_direction), 0.0), material.shininess);
-  vec3  diff_tex           = vec3(texture(material.diffuse, uv_coords));
+  vec3  diff_tex           = vec3(texture(material.diffuse1, fs_in.uv_coords));
   vec3  ambient            = light.ambient * diff_tex;
   vec3  diffuse            = light.diffuse * (diff * diff_tex) * intensity;
-  vec3  specular           = light.specular * (spec * vec3(texture(material.specular, uv_coords))) * intensity;
+  vec3  specular           = light.specular * (spec * vec3(texture(material.specular1, fs_in.uv_coords))) * intensity;
 
   return ambient + diffuse + specular;
 }

shaders/light_vert.glsl

@@ -0,0 +1,18 @@
+#version 330 core
+
+#define POINT_LIGHT_COUNT 4
+
+layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
+layout(location=2) in vec2 uv;
+layout(location=3) in mat4 model;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+void main() {
+  gl_Position = projection * view * model * vec4(position, 1.0);
+};

shaders/normal_frag.glsl

@@ -0,0 +1,7 @@
+#version 330 core
+
+out vec4 color;
+
+void main() {
+  color = vec4(1.0, 1.0, 0.0, 1.0);
+}

shaders/normal_geo.glsl

@@ -0,0 +1,34 @@
+#version 330 core
+
+#define MAGNITUDE 0.1
+
+layout (triangles) in;
+layout (line_strip, max_vertices = 6) out;
+
+uniform float time;
+
+in VS_OUT {
+  vec3 vert_normal;
+} gs_in[];
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+void generate_line(int index) {
+  gl_Position = projection * gl_in[index].gl_Position;
+  EmitVertex();
+
+  gl_Position = projection * (gl_in[index].gl_Position + vec4(gs_in[index].vert_normal, 1.0) * MAGNITUDE);
+  EmitVertex();
+
+  EndPrimitive();
+}
+
+void main() {
+  for (int i = 0; i < 3; ++i) {
+    generate_line(i);
+  }
+}

shaders/normal_vert.glsl

@@ -0,0 +1,25 @@
+#version 330 core
+
+layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
+layout(location=2) in vec2 uv;
+
+uniform mat3 normal_mat;
+uniform mat4 model;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+// interface block
+out VS_OUT {
+  vec3 vert_normal;
+} vs_out;
+
+void main() {
+  vs_out.vert_normal = normal_mat * normal;
+
+  gl_Position = view * model * vec4(position, 1.0);
+};

shaders/pp_frag.glsl

@@ -0,0 +1,17 @@
+#version 330 core
+
+struct Material {
+  sampler2D diffuse1;
+  sampler2D specular1;
+  float shininess;
+};
+
+in vec2 uv_coords;
+
+uniform Material material;
+
+out vec4 color;
+
+void main() {
+  color = vec4(vec3(texture(material.diffuse1, uv_coords)), 1.0);
+}

shaders/pp_vert.glsl

@@ -0,0 +1,12 @@
+#version 330 core
+
+layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
+layout(location=2) in vec2 uv;
+
+out vec2 uv_coords;
+
+void main() {
+  gl_Position = vec4(position.x, position.y, 0.0, 1.0);
+  uv_coords   = uv;
+}

shaders/reflective_frag.glsl

@@ -0,0 +1,24 @@
+#version 330 core
+
+in VS_OUT {
+  vec3 vert_normal;
+  vec3 frag_position;
+  vec2 uv_coords;
+} fs_in;
+
+uniform samplerCube cubemap;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+out vec4 color;
+
+void main() {
+  vec3 view_direction    = normalize(fs_in.frag_position - camera_position);
+  vec3 reflect_direction = reflect(view_direction, normalize(fs_in.vert_normal));
+
+  color = vec4(texture(cubemap, reflect_direction).rgb, 1.0);
+}

shaders/refractive_frag.glsl

@@ -0,0 +1,27 @@
+#version 330 core
+
+#define AIR_IOR 1.0
+#define GLASS_IOR 1.52
+
+in VS_OUT {
+  vec3 vert_normal;
+  vec3 frag_position;
+  vec2 uv_coords;
+} fs_in;
+
+uniform samplerCube cubemap;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+out vec4 color;
+
+void main() {
+  vec3 view_direction    = normalize(fs_in.frag_position - camera_position);
+  vec3 refract_direction = refract(view_direction, normalize(fs_in.vert_normal), AIR_IOR / GLASS_IOR);
+
+  color = vec4(texture(cubemap, refract_direction).rgb, 1.0);
+}

shaders/sb_frag.glsl

@@ -0,0 +1,11 @@
+#version 330 core
+
+in vec3 uv_coords;
+
+uniform samplerCube cubemap;
+
+out vec4 color;
+
+void main() {
+  color = texture(cubemap, uv_coords);
+}

shaders/sb_vert.glsl

@@ -0,0 +1,21 @@
+#version 330 core
+
+layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
+layout(location=2) in vec2 uv;
+
+uniform mat4 sb_view;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+out vec3 uv_coords;
+
+void main() {
+  vec4 pos    = projection * sb_view * vec4(position, 1.0);
+  gl_Position = pos.xyww;
+  uv_coords   = position;
+}

shaders/vert.glsl

@@ -4,18 +4,26 @@ layout(location=0) in vec3 position;
 layout(location=1) in vec3 normal;
 layout(location=2) in vec2 uv;
 
-out vec3 vert_normal;
-out vec3 frag_position;
-out vec2 uv_coords;
-
 uniform mat3 normal_mat;
 uniform mat4 model;
-uniform mat4 view;
+
-uniform mat4 projection;
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+// interface block
+out VS_OUT {
+  vec3 vert_normal;
+  vec3 frag_position;
+  vec2 uv_coords;
+} vs_out;
 
 void main() {
-  vert_normal   = normal_mat * normal;
+  vs_out.frag_position = vec3(model * vec4(position, 1.0));
-  frag_position = vec3(model * vec4(position, 1.0));
+  vs_out.vert_normal   = normal_mat * normal;
-  uv_coords     = uv;
+  vs_out.uv_coords     = uv;
+
   gl_Position = projection * view * model * vec4(position, 1.0);
 };

src/main.cc

@@ -14,6 +14,14 @@
 #include "glm/gtx/rotate_vector.hpp"
 #include "glm/gtx/string_cast.hpp"
 
+// Assimp
+#include "assimp/Importer.hpp"
+#include "assimp/postprocess.h"
+#include "assimp/scene.h"
+#include "assimp/mesh.h"
+#include "assimp/material.h"
+#include "assimp/types.h"
+
 // SDL
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_timer.h>
@@ -40,17 +48,27 @@
 #define max(a, b) (a > b ? a : b)
 #define clamp(v, a, b) (min(max(v, a), b))
 
+#define WIREFRAME 0
+#define NORMALS 0
+#define MSAA 1
+#define POINT_LIGHTS 1
+
+#if MSAA
+#define MSAA_SAMPLE_COUNT 4
+#endif
+
 enum exit_codes : int {
   EXIT_CODE_SUCCESS,
   EXIT_CODE_SDL_INIT_FAILED,
   EXIT_CODE_WINDOW_CREATION_FAILED,
   EXIT_CODE_OPENGL_CONTEXT_FAILED,
   EXIT_CODE_GLAD_LOADER_FAILED,
+  EXIT_CODE_INCOMPLETE_FRAME_BUFFER,
 };
 
 class Shader {
   public:
-    Shader(const std::string &vert_file, const std::string &frag_file);
+    Shader(const std::string &vert_file, const std::string &frag_file, const std::string &geo_file = "");
     ~Shader();
     void activate();
     void set_int(const char *name, int value);
@@ -59,24 +77,32 @@ class Shader {
     void set_vec4(const char *name, glm::vec4 vector);
     void set_mat3(const char *name, glm::mat3 matrix);
     void set_mat4(const char *name, glm::mat4 matrix);
+    void set_uniform_block_binding_point(const char *block_name, GLuint binding_point);
     GLuint program;
   private:
-    void link_program(GLuint vert, GLuint frag);
+    void link_program(GLuint vert, GLuint frag, GLuint geo);
     GLuint load_and_compile_shader(const std::string &filepath, GLenum shader_type);
     std::string load_shader_from_file(const std::string &filepath);
     static const char *get_shader_type_string(GLenum shader_type);
 };
 
+enum TextureType : unsigned char {
+  TEXTURE_TYPE_DIFFUSE,
+  TEXTURE_TYPE_SPECULAR,
+};
+
 class Texture2D {
   public:
-    Texture2D(const char *filename, GLint texture_unit, const char *name);
+    Texture2D(const char *filename, GLint texture_unit, TextureType type);
     ~Texture2D();
     void activate() const;
+    std::string name(unsigned int index) const;
     int width;
     int height;
     int channels;
+    const char *filename;
     GLint texture_unit;
-    std::string name;
+    TextureType type;
   private:
     GLuint texture;
     GLint format;
@@ -95,12 +121,51 @@ class Mesh {
     std::vector<Texture2D> textures;
 
     Mesh(std::vector<Vertex> vertices, std::vector<GLuint> indices, std::vector<Texture2D> textures);
+    void activate();
+    void deactivate();
     void draw(Shader &Shader);
+    void draw_instanced(Shader &Shader, unsigned int count = 1);
   private:
     GLuint vao, vbo, ebo;
     void setup_mesh();
+    void set_mesh_textures_for_drawing(Shader &shader);
 };
 
+class Model {
+  public:
+    Model(const char *path) {
+      load_model(path);
+    }
+
+    void draw(Shader &shader);
+  private:
+    std::vector<Texture2D> loaded_textures;
+    std::vector<Mesh> meshes;
+    std::string directory;
+    GLint texture_unit = GL_TEXTURE0;
+
+    void load_model(std::string path);
+    void process_node(aiNode *node, const aiScene *scene);
+    Mesh process_mesh(aiMesh *mesh, const aiScene *scene);
+    std::vector<Texture2D> load_material_textures(aiMaterial *mat, aiTextureType type);
+};
+
+struct FrameBuffer {
+  GLuint fbo;
+  GLuint color;
+  GLuint depth_stencil;
+  GLuint width;
+  GLuint height;
+};
+
+FrameBuffer create_normal_frame_buffer(unsigned int width, unsigned int height);
+#if MSAA
+FrameBuffer create_multisample_frame_buffer(unsigned int width, unsigned int height);
+void blit_multisample_frame_buffer(const FrameBuffer &multisample_buffer, const FrameBuffer &normal_buffer);
+#endif
+void delete_frame_buffer(FrameBuffer &buffer);
+GLuint load_cubemap(std::vector<std::string> textures);
+
 int main() {
   if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
     return EXIT_CODE_SDL_INIT_FAILED;
@@ -112,6 +177,11 @@ int main() {
   SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
   SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
 
+#if MSAA
+  SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
+  SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, MSAA_SAMPLE_COUNT);
+#endif
+
   SDL_Window *window = SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                         WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
   if (!window) {
@@ -127,14 +197,21 @@ int main() {
     return EXIT_CODE_GLAD_LOADER_FAILED;
   }
 
+#if MSAA
+  glEnable(GL_MULTISAMPLE);
+#endif
+
   SDL_SetRelativeMouseMode(SDL_TRUE);
   SDL_WarpMouseInWindow(window, WINDOW_HALF_WIDTH, WINDOW_HALF_HEIGHT);
 
-  stbi_set_flip_vertically_on_load(true);
-
   glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
 
-  glEnable(GL_DEPTH_TEST);
+#if MSAA
+  FrameBuffer multisample_buffer = create_multisample_frame_buffer(WINDOW_WIDTH, WINDOW_HEIGHT);
+  FrameBuffer offscreen_buffer   = create_normal_frame_buffer(WINDOW_WIDTH, WINDOW_HEIGHT);
+#else
+  FrameBuffer offscreen_buffer = create_normal_frame_buffer(WINDOW_WIDTH, WINDOW_HEIGHT);
+#endif
 
   std::vector<Vertex> vertices = {
     // positions                           // normals                      // texture coords
@@ -179,26 +256,74 @@ int main() {
     13, 15, 16
   };
 
-  std::vector<Texture2D> textures = {
+  Model suzanne = {"models/suzanne/suzanne.obj"};
-    Texture2D("images/container2.png", GL_TEXTURE0, "material.diffuse"),
-    Texture2D("images/container2_specular.png", GL_TEXTURE1, "material.specular"),
-  };
-
-  Mesh container = {vertices, indices, textures};
   Mesh light    = {vertices, indices, {}};
 
+  std::vector<Vertex> skybox_vertices = {
+    Vertex{glm::vec3(-1.0f,  1.0f, -1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3(-1.0f, -1.0f, -1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3( 1.0f, -1.0f, -1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3( 1.0f,  1.0f, -1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3(-1.0f, -1.0f,  1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3(-1.0f,  1.0f,  1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3( 1.0f, -1.0f,  1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+    Vertex{glm::vec3( 1.0f,  1.0f,  1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+  };
+
+  std::vector<GLuint> skybox_indices = {
+    0, 1, 2,
+    2, 3, 0,
+    4, 1, 0,
+    0, 5, 4,
+    2, 6, 7,
+    7, 3, 2,
+    4, 5, 7,
+    7, 6, 4,
+    0, 3, 7,
+    7, 5, 0,
+    1, 4, 2,
+    2, 4, 6,
+  };
+
+  Mesh skybox = {skybox_vertices, skybox_indices, {}};
+
+  std::vector<Vertex> screen_vertices = {
+    Vertex{glm::vec3(-1.0f, -1.0f, 0.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(0.0f, 0.0f)},
+    Vertex{glm::vec3( 1.0f, -1.0f, 0.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 0.0f)},
+    Vertex{glm::vec3(-1.0f,  1.0f, 0.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(0.0f, 1.0f)},
+    Vertex{glm::vec3( 1.0f,  1.0f, 0.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec2(1.0f, 1.0f)},
+  };
+
+  std::vector<GLuint> screen_indices = {
+    0, 1, 2,
+    2, 1, 3,
+  };
+
+  Mesh screen = {screen_vertices, screen_indices, {}};
+
   Shader main_shader       {"shaders/vert.glsl",        "shaders/frag.glsl"};
-  Shader light_shader {"shaders/vert.glsl", "shaders/light_frag.glsl"};
+  Shader skybox_shader     {"shaders/sb_vert.glsl",     "shaders/sb_frag.glsl"};
+  Shader reflective_shader {"shaders/vert.glsl",        "shaders/reflective_frag.glsl"};
+  Shader refractive_shader {"shaders/vert.glsl",        "shaders/refractive_frag.glsl"};
+  Shader post_processing   {"shaders/pp_vert.glsl",     "shaders/pp_frag.glsl"};
+#if NORMALS
+  Shader normal_vis_shader {"shaders/normal_vert.glsl", "shaders/normal_frag.glsl", "shaders/normal_geo.glsl"};
+#endif
+
+#if POINT_LIGHTS
+  Shader light_shader      {"shaders/light_vert.glsl",  "shaders/light_frag.glsl"};
+  std::vector<glm::mat4> light_shader_model_mats;
+#endif
 
   const float camera_speed  = 25.0f;
-  glm::vec3 camera_position  = glm::vec3(-2.0f, 0.0f, 6.0f);
+  glm::vec3 camera_position = glm::vec3(-2.5f, 0.0f, 8.0f);
   glm::vec3 camera_forward  = glm::vec3(0.0f);
   glm::vec3 world_up        = glm::vec3(0.0f, 1.0f, 0.0f);
   glm::vec3 light_ambient   = glm::vec3(0.2f, 0.2f, 0.2f);
   glm::vec3 light_diffuse   = glm::vec3(0.75f, 0.75f, 0.75f);
   glm::vec3 light_specular  = glm::vec3(1.0f, 1.0f, 1.0f);
 
-  float yaw   = -70.0f;
+  float yaw   = -75.0f;
   float pitch =   0.0f;
 
   glm::mat4 model      = glm::mat4(1.0f);
@@ -206,41 +331,25 @@ int main() {
   glm::mat4 projection = glm::perspective(glm::radians(45.0f), (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT, 0.1f, 100.0f);
   glm::mat3 normal_mat = glm::mat3(1.0f);
 
-  main_shader.set_mat4 ("projection", projection);
-  main_shader.set_vec3 ("material.specular", glm::vec3(0.5f, 0.5f, 0.5f));
-  main_shader.set_float("material.shininess", 32.0f);
-
-  light_shader.set_mat4("projection", projection);
-
-  std::vector<glm::vec3> cube_positions = {
-      glm::vec3( 0.0f,  0.0f,  0.0f),
-      glm::vec3( 4.0f,  6.0f, -15.0f),
-      glm::vec3(-3.5f, -3.2f, -2.5f),
-      glm::vec3(-5.8f, -3.0f, -12.3f),
-      glm::vec3( 4.4f, -1.4f, -3.5f),
-      glm::vec3(-3.7f,  4.0f, -7.5f),
-      glm::vec3( 3.3f, -3.0f, -2.5f),
-      glm::vec3( 3.5f,  3.0f, -2.5f),
-      glm::vec3( 3.5f,  1.2f, -1.5f),
-      glm::vec3(-3.3f,  2.0f, -1.5f)
-  };
-
   std::vector<glm::vec3> point_light_positions = {
     glm::vec3( 0.7f,  0.2f,  2.0f),
     glm::vec3( 2.3f, -3.3f, -4.0f),
     glm::vec3(-4.0f,  2.0f, -12.0f),
-    glm::vec3( 0.0f,  0.0f, -3.0f)
+    glm::vec3( 1.0f,  0.0f, -18.0f)
   };
 
+  // Setup material
+  main_shader.set_float("material.shininess", 32.0f);
+
   // Setup lights
   main_shader.set_vec3("directional_light.direction", glm::vec3(-0.2f, -1.0f, -0.3f));
   main_shader.set_vec3("directional_light.ambient", light_ambient);
-  main_shader.set_vec3("directional_light.diffuse", light_diffuse);
+  main_shader.set_vec3("directional_light.diffuse", light_diffuse * 0.25f);
   main_shader.set_vec3("directional_light.specular", light_specular);
 
   main_shader.set_vec3("spot_light.ambient", light_ambient);
-  main_shader.set_vec3("spot_light.diffuse", light_diffuse);
+  main_shader.set_vec3("spot_light.diffuse", light_diffuse * 0.5f);
-  main_shader.set_vec3("spot_light.specular", light_specular);
+  main_shader.set_vec3("spot_light.specular", light_specular * 0.25f);
 
   for (int i = 0; i < point_light_positions.size(); ++i) {
     char base[256]      = {0};
@@ -263,8 +372,8 @@ int main() {
 
     main_shader.set_vec3(position, point_light_positions[i]);
     main_shader.set_vec3(ambient, light_ambient);
-    main_shader.set_vec3(diffuse, light_diffuse);
+    main_shader.set_vec3(diffuse, light_diffuse * 0.25f);
-    main_shader.set_vec3(specular, light_specular);
+    main_shader.set_vec3(specular, light_specular * 0.5f);
     main_shader.set_float(constant, 1.0f);
     main_shader.set_float(linear, 0.09f);
     main_shader.set_float(quadratic, 0.032f);
@@ -277,8 +386,76 @@ int main() {
     memset(constant,  0, sizeof(constant));
     memset(linear,    0, sizeof(linear));
     memset(quadratic, 0, sizeof(quadratic));
+
+#if POINT_LIGHTS
+    glm::mat4 light_shader_model_mat = glm::translate(glm::mat4(1.0f), point_light_positions[i]);
+    light_shader_model_mat = glm::scale(light_shader_model_mat, glm::vec3(0.2f));
+    light_shader_model_mats.push_back(light_shader_model_mat);
+#endif
   }
 
+#if POINT_LIGHTS
+  std::size_t vec4_size = sizeof(glm::vec4);
+
+  light.activate();
+
+  GLuint instanceVBO;
+  glGenBuffers(1, &instanceVBO);
+  glBindBuffer(GL_ARRAY_BUFFER, instanceVBO);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(glm::mat4) * light_shader_model_mats.size(), glm::value_ptr(light_shader_model_mats[0]), GL_STATIC_DRAW);
+
+  // Set up attribute pointers for each column of the matrix
+  for (unsigned int i = 3; i < 7; ++i) {
+    glVertexAttribPointer(i, 4, GL_FLOAT, GL_FALSE, 4 * vec4_size, (void *)((i - 3) * vec4_size));
+    glEnableVertexAttribArray(i);
+    glVertexAttribDivisor(i, 1);
+  }
+
+  light.deactivate();
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+#endif
+
+  // Load cube map
+  std::vector<std::string> cube_map_textures = {
+    "images/skybox/right.jpg",
+    "images/skybox/left.jpg",
+    "images/skybox/top.jpg",
+    "images/skybox/bottom.jpg",
+    "images/skybox/front.jpg",
+    "images/skybox/back.jpg",
+  };
+
+  GLuint cubemap = load_cubemap(cube_map_textures);
+
+  // Generate and bind uniform buffer
+  GLuint ubo;
+  GLuint ubo_binding_point = 0;
+  glGenBuffers(1, &ubo);
+  glBindBuffer(GL_UNIFORM_BUFFER, ubo);
+  glBufferData(GL_UNIFORM_BUFFER, 144, NULL, GL_STATIC_DRAW);
+  // Bind the uniform buffer object to a binding point
+  // Can also be done using glBindBufferRange instead of glBindBufferBase
+  glBindBufferBase(GL_UNIFORM_BUFFER, ubo_binding_point, ubo);
+
+  // Set the shaders binding points
+  main_shader.set_uniform_block_binding_point      ("Common", ubo_binding_point);
+  skybox_shader.set_uniform_block_binding_point    ("Common", ubo_binding_point);
+  reflective_shader.set_uniform_block_binding_point("Common", ubo_binding_point);
+  refractive_shader.set_uniform_block_binding_point("Common", ubo_binding_point);
+
+#if NORMALS
+  normal_vis_shader.set_uniform_block_binding_point("Common", ubo_binding_point);
+#endif
+
+#if POINT_LIGHTS
+  light_shader.set_uniform_block_binding_point     ("Common", ubo_binding_point);
+#endif
+
+  // Add projection matrix to uniform buffer
+  glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(glm::mat4), glm::value_ptr(projection));
+  glBindBuffer(GL_UNIFORM_BUFFER, 0);
+
   const float sensitivity   = 0.1f;
   int last_mouse_x          = WINDOW_HALF_WIDTH;
   int last_mouse_y          = WINDOW_HALF_HEIGHT;
@@ -342,6 +519,14 @@ int main() {
             SDL_GL_GetDrawableSize(wnd, &w, &h);
             glViewport(0, 0, w, h);
             SDL_WarpMouseInWindow(wnd, (int)(w * 0.5f), (int)(h * 0.5f));
+
+            // Recreate offscreen frame buffer
+            delete_frame_buffer(offscreen_buffer);
+            offscreen_buffer = create_normal_frame_buffer(w, h);
+#if MSAA
+            delete_frame_buffer(multisample_buffer);
+            multisample_buffer = create_multisample_frame_buffer(w, h);
+#endif
           }
           break;
       }
@@ -353,36 +538,96 @@ int main() {
     camera_forward   = glm::normalize(camera_forward);
 
     view = glm::lookAt(camera_position, camera_position + camera_forward, world_up);
-    main_shader.set_vec3("camera_position", camera_position);
+
+    // Add view matrix and camera_position to uniform buffer
+    glBindBuffer(GL_UNIFORM_BUFFER, ubo);
+    glBufferSubData(GL_UNIFORM_BUFFER, sizeof(glm::mat4), sizeof(glm::mat4), glm::value_ptr(view));
+    glBufferSubData(GL_UNIFORM_BUFFER, 2 * sizeof(glm::mat4), sizeof(glm::vec3), glm::value_ptr(camera_position));
+    glBindBuffer(GL_UNIFORM_BUFFER, 0);
+
     main_shader.set_vec3("spot_light.position", camera_position);
     main_shader.set_vec3("spot_light.direction", camera_forward);
     main_shader.set_float("spot_light.cutoff", glm::cos(glm::radians(12.5)));
     main_shader.set_float("spot_light.outer_cutoff", glm::cos(glm::radians(17.5)));
-    main_shader.set_mat4("view", view);
+    skybox_shader.set_mat4("sb_view", glm::mat4(glm::mat3(view)));
-    light_shader.set_mat4("view", view);
+
+    // Main render pass
+#if MSAA
+    glBindFramebuffer(GL_FRAMEBUFFER, multisample_buffer.fbo);
+#else
+    glBindFramebuffer(GL_FRAMEBUFFER, offscreen_buffer.fbo);
+#endif
 
     glClearColor(0.04f, 0.08f, 0.08f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-    for (int i = 0; i < cube_positions.size(); ++i) {
+    glEnable(GL_DEPTH_TEST);
-      model = glm::translate(glm::mat4(1.0f), cube_positions[i]);
+    glDepthFunc(GL_LEQUAL);
-      model = glm::rotate(model, glm::radians(10.0f * i), glm::vec3(1.0f, 0.3f, 0.5f));
+    glEnable(GL_CULL_FACE);
+
+    model      = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, 0.0f));
     normal_mat = glm::transpose(glm::inverse(model));
     main_shader.activate();
     main_shader.set_mat4("model", model);
     main_shader.set_mat3("normal_mat", normal_mat);
-      container.draw(main_shader);
+    suzanne.draw(main_shader);
-    }
 
-    // Draw light source
+#if NORMALS
-    for (int i = 0; i < point_light_positions.size(); ++i) {
+    normal_mat = glm::transpose(glm::inverse(view * model));
-      model = glm::translate(glm::mat4(1.0f), point_light_positions[i]);
+    normal_vis_shader.activate();
-      model = glm::scale(model, glm::vec3(0.2f));
+    normal_vis_shader.set_mat4("model", model);
-      light_shader.activate();
+    normal_vis_shader.set_mat3("normal_mat", normal_mat);
-      light_shader.set_mat4("model", model);
+    suzanne.draw(normal_vis_shader);
+#endif
+
+    model      = glm::translate(glm::mat4(1.0f), glm::vec3(3.0f, 0.0f, 0.0f));
+    normal_mat = glm::transpose(glm::inverse(model));
+    reflective_shader.set_mat4("model", model);
+    reflective_shader.set_mat3("normal_mat", normal_mat);
+    suzanne.draw(reflective_shader);
+
+    glDisable(GL_CULL_FACE);
+    model      = glm::translate(glm::mat4(1.0f), glm::vec3(-3.0f, 0.0f, 0.0f));
+    normal_mat = glm::transpose(glm::inverse(model));
+    refractive_shader.set_mat4("model", model);
+    refractive_shader.set_mat3("normal_mat", normal_mat);
+    suzanne.draw(refractive_shader);
+
+#if POINT_LIGHTS
+    // Draw point lights
     light_shader.set_vec3("light_diffuse", light_diffuse);
-      light.draw(light_shader);
+    light.draw_instanced(light_shader, point_light_positions.size());
-    }
+#endif
+
+    // Draw skybox
+    skybox_shader.activate();
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+    skybox_shader.set_int("cubemap", 0);
+    skybox.draw(skybox_shader);
+
+#if WIREFRAME
+    // wireframe mode
+    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+#endif
+
+#if MSAA
+    blit_multisample_frame_buffer(multisample_buffer, offscreen_buffer);
+#endif
+
+    // Post processing pass
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+    glDisable(GL_DEPTH_TEST);
+    glDisable(GL_CULL_FACE);
+
+    post_processing.activate();
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, offscreen_buffer.color);
+    post_processing.set_int("image_texture", 0);
+    screen.draw(post_processing);
 
     SDL_GL_SwapWindow(window);
   }
@@ -395,12 +640,19 @@ int main() {
 }
 
 
-Shader::Shader(const std::string &vert_file, const std::string &frag_file) {
+Shader::Shader(const std::string &vert_file, const std::string &frag_file, const std::string &geo_file) {
   GLuint vert = load_and_compile_shader(vert_file, GL_VERTEX_SHADER);
   GLuint frag = load_and_compile_shader(frag_file, GL_FRAGMENT_SHADER);
-  link_program(vert, frag);
+  GLuint geo  = 0;
+  if (geo_file.size() > 0) {
+    geo = load_and_compile_shader(geo_file, GL_GEOMETRY_SHADER);
+  }
+  link_program(vert, frag, geo);
   glDeleteShader(vert);
   glDeleteShader(frag);
+  if (geo > 0) {
+    glDeleteShader(geo);
+  }
 }
 
 Shader::~Shader() {
@@ -445,10 +697,18 @@ void Shader::set_mat4(const char *name, glm::mat4 matrix) {
   glUniformMatrix4fv(glGetUniformLocation(program, name), 1, GL_FALSE, glm::value_ptr(matrix));
 }
 
-void Shader::link_program(GLuint vert, GLuint frag) {
+void Shader::set_uniform_block_binding_point(const char *block_name, GLuint binding_point) {
+  GLuint block_index = glGetUniformBlockIndex(program, block_name);
+  glUniformBlockBinding(program, block_index, binding_point);
+}
+
+void Shader::link_program(GLuint vert, GLuint frag, GLuint geo) {
   program = glCreateProgram();
   glAttachShader(program, vert);
   glAttachShader(program, frag);
+  if (geo > 0) {
+    glAttachShader(program, geo);
+  }
 
   glLinkProgram(program);
   GLint program_linked;
@@ -531,7 +791,7 @@ const char *Shader::get_shader_type_string(GLenum shader_type) {
   return output;
 }
 
-Texture2D::Texture2D(const char *filename, GLint texture_unit, const char *name) : texture_unit(texture_unit), name(name) {
+Texture2D::Texture2D(const char *filename, GLint texture_unit, TextureType type) : filename(filename), texture_unit(texture_unit), type(type) {
   uint8_t *image = stbi_load(filename, &width, &height, &channels, 0);
   if (!image) {
     return;
@@ -562,6 +822,23 @@ void Texture2D::activate() const {
   glBindTexture(GL_TEXTURE_2D, texture);
 }
 
+std::string Texture2D::name(unsigned int index) const {
+  std::string output = "material.";
+
+  switch (type) {
+    case TEXTURE_TYPE_DIFFUSE:
+      output += "diffuse";
+      break;
+    case TEXTURE_TYPE_SPECULAR:
+      output += "specular";
+      break;
+  }
+
+  output += std::to_string(index);
+
+  return output.c_str();
+}
+
 Mesh::Mesh(std::vector<Vertex> vertices, std::vector<GLuint> indices, std::vector<Texture2D> textures)
   : vertices(vertices), indices(indices), textures(textures) {
     setup_mesh();
@@ -588,14 +865,247 @@ void Mesh::setup_mesh() {
   glEnableVertexAttribArray(2);
 }
 
-void Mesh::draw(Shader &shader) {
+void Mesh::set_mesh_textures_for_drawing(Shader &shader) {
+  unsigned int diffuse = 1;
+  unsigned int specular = 1;
+  unsigned int index;
+
   for (int i = 0; i < textures.size(); ++i) {
     const Texture2D &texture = textures[i];
-    shader.set_int(texture.name.c_str(), texture.texture_unit - GL_TEXTURE0);
+    index = texture.type == TEXTURE_TYPE_DIFFUSE ? diffuse++ : specular++;
+    shader.set_int(texture.name(index).c_str(), texture.texture_unit - GL_TEXTURE0);
     texture.activate();
   }
+}
 
+void Mesh::activate() {
   glBindVertexArray(vao);
-  glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, (void *)0);
+}
+
+void Mesh::deactivate() {
   glBindVertexArray(0);
 }
+
+void Mesh::draw(Shader &shader) {
+  set_mesh_textures_for_drawing(shader);
+  activate();
+  glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, (void *)0);
+  deactivate();
+}
+
+void Mesh::draw_instanced(Shader &shader, unsigned int count) {
+  set_mesh_textures_for_drawing(shader);
+  glBindVertexArray(vao);
+  glDrawElementsInstanced(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, (void *)0, count);
+  glBindVertexArray(0);
+}
+
+void Model::draw(Shader &shader) {
+  shader.activate();
+
+  for (int i = 0; i < meshes.size(); ++i) {
+    meshes[i].draw(shader);
+  }
+}
+
+void Model::load_model(std::string path) {
+  Assimp::Importer importer;
+  const aiScene *scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_FlipUVs);
+  if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) {
+    printf("Failed to load model: %s. Error: %s\n", path.c_str(), importer.GetErrorString());
+    return;
+  }
+
+  directory = path.substr(0, path.find_last_of('/'));
+  process_node(scene->mRootNode, scene);
+}
+
+void Model::process_node(aiNode *node, const aiScene *scene) {
+  for (unsigned int i = 0; i < node->mNumMeshes; ++i) {
+    aiMesh *mesh = scene->mMeshes[node->mMeshes[i]];
+    meshes.push_back(process_mesh(mesh, scene));
+  }
+
+  for (unsigned int i = 0; i < node->mNumChildren; ++i) {
+    process_node(node->mChildren[i], scene);
+  }
+}
+
+Mesh Model::process_mesh(aiMesh *mesh, const aiScene *scene) {
+  std::vector<Vertex> vertices;
+  std::vector<GLuint> indices;
+  std::vector<Texture2D> textures;
+
+  for (unsigned int i = 0; i < mesh->mNumVertices; ++i) {
+    Vertex vertex;
+
+    vertex.position = glm::vec3(mesh->mVertices[i].x, mesh->mVertices[i].y, mesh->mVertices[i].z);
+    vertex.normal = glm::vec3(mesh->mNormals[i].x, mesh->mNormals[i].y, mesh->mNormals[i].z);
+    if (mesh->mTextureCoords[0]) {
+      vertex.tex_coord = glm::vec2(mesh->mTextureCoords[0][i].x, mesh->mTextureCoords[0][i].y);
+    } else {
+      vertex.tex_coord = glm::vec2(0.0f, 0.0f);
+    }
+
+    vertices.push_back(vertex);
+  }
+
+  for (unsigned int i = 0; i < mesh->mNumFaces; ++i) {
+    aiFace face = mesh->mFaces[i];
+    for (unsigned int j = 0; j < face.mNumIndices; ++j) {
+      indices.push_back(face.mIndices[j]);
+    }
+  }
+
+  if (mesh->mMaterialIndex >= 0) {
+    aiMaterial *material = scene->mMaterials[mesh->mMaterialIndex];
+
+    std::vector<Texture2D> diffuse_maps = load_material_textures(material, aiTextureType_DIFFUSE);
+    textures.insert(textures.end(), diffuse_maps.begin(), diffuse_maps.end());
+
+    std::vector<Texture2D> specular_maps = load_material_textures(material, aiTextureType_SPECULAR);
+    textures.insert(textures.end(), specular_maps.begin(), specular_maps.end());
+  }
+
+  return Mesh(vertices, indices, textures);
+}
+
+std::vector<Texture2D> Model::load_material_textures(aiMaterial *material, aiTextureType type) {
+  std::vector<Texture2D> textures;
+  for (unsigned int i = 0; i < material->GetTextureCount(type); ++i) {
+    aiString path;
+    material->GetTexture(type, i, &path);
+    std::string absolute_path = directory + '/' + path.C_Str();
+
+    bool skip = false;
+    for (unsigned int j = 0; j < loaded_textures.size(); ++j) {
+      if (std::strcmp(loaded_textures[j].filename, absolute_path.c_str()) == 0) {
+        textures.push_back(loaded_textures[j]);
+        skip = true;
+        break;
+      }
+    }
+
+    if (!skip) {
+      TextureType tex_type = type == aiTextureType_DIFFUSE ? TEXTURE_TYPE_DIFFUSE : TEXTURE_TYPE_SPECULAR;
+      Texture2D texture = {absolute_path.c_str(), texture_unit++, tex_type};
+      textures.push_back(texture);
+    }
+  }
+
+  return textures;
+}
+
+FrameBuffer create_normal_frame_buffer(unsigned int width, unsigned int height) {
+  FrameBuffer buffer = {};
+
+  glGenFramebuffers(1, &buffer.fbo);
+  glBindFramebuffer(GL_FRAMEBUFFER, buffer.fbo);
+
+  // Create color texture
+  glGenTextures(1, &buffer.color);
+  glBindTexture(GL_TEXTURE_2D, buffer.color);
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, buffer.color, 0);
+
+  // Create depth and stencil buffers
+  glGenRenderbuffers(1, &buffer.depth_stencil);
+  glBindRenderbuffer(GL_RENDERBUFFER, buffer.depth_stencil);
+  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
+
+  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, buffer.depth_stencil);
+
+  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+    printf("Incomplete frame buffer\n");
+    exit(EXIT_CODE_INCOMPLETE_FRAME_BUFFER);
+  }
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+  glBindTexture(GL_TEXTURE_2D, 0);
+  glBindRenderbuffer(GL_RENDERBUFFER, 0);
+
+  buffer.width  = width;
+  buffer.height = height;
+
+  return buffer;
+}
+
+#if MSAA
+FrameBuffer create_multisample_frame_buffer(unsigned int width, unsigned int height) {
+  FrameBuffer buffer = {};
+
+  glGenFramebuffers(1, &buffer.fbo);
+  glBindFramebuffer(GL_FRAMEBUFFER, buffer.fbo);
+
+  // Create color texture
+  glGenTextures(1, &buffer.color);
+  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, buffer.color);
+  glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, MSAA_SAMPLE_COUNT, GL_RGB, width, height, GL_TRUE);
+  glTexParameteri(GL_TEXTURE_2D_MULTISAMPLE, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D_MULTISAMPLE, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, buffer.color, 0);
+
+  // Create depth and stencil buffers
+  glGenRenderbuffers(1, &buffer.depth_stencil);
+  glBindRenderbuffer(GL_RENDERBUFFER, buffer.depth_stencil);
+  glRenderbufferStorageMultisample(GL_RENDERBUFFER, MSAA_SAMPLE_COUNT, GL_DEPTH24_STENCIL8, width, height);
+
+  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, buffer.depth_stencil);
+
+  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+    printf("Incomplete frame buffer\n");
+    exit(EXIT_CODE_INCOMPLETE_FRAME_BUFFER);
+  }
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
+  glBindRenderbuffer(GL_RENDERBUFFER, 0);
+
+  buffer.width  = width;
+  buffer.height = height;
+
+  return buffer;
+}
+
+void blit_multisample_frame_buffer(const FrameBuffer &multisample_buffer, const FrameBuffer &normal_buffer) {
+  glBindFramebuffer(GL_READ_FRAMEBUFFER, multisample_buffer.fbo);
+  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, normal_buffer.fbo);
+  glBlitFramebuffer(
+      0, 0, multisample_buffer.width, multisample_buffer.height,
+      0, 0, normal_buffer.width, normal_buffer.height,
+      GL_COLOR_BUFFER_BIT, GL_NEAREST
+  );
+}
+#endif
+
+void delete_frame_buffer(FrameBuffer &buffer) {
+  glDeleteFramebuffers(1, &buffer.fbo);
+  glDeleteTextures(1, &buffer.color);
+  glDeleteRenderbuffers(1, &buffer.depth_stencil);
+}
+
+GLuint load_cubemap(std::vector<std::string> textures) {
+  GLuint cubemap;
+  glGenTextures(1, &cubemap);
+  glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+
+  int width, height, channels;
+  uint8_t *tex;
+  for (unsigned int i = 0; i < textures.size(); ++i) {
+    tex = stbi_load(textures[i].c_str(), &width, &height, &channels, 0);
+    glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, tex);
+    stbi_image_free(tex);
+  }
+
+  glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+  return cubemap;
+}