feat: add world builder state

3 files changed, 762 insertions, 15 deletions

diff --git a/src/states/config_state.cpp b/src/states/config_state.cpp
index 1f1ef16..41fbaad 100644
--- a/src/states/config_state.cpp
+++ b/src/states/config_state.cpp
@@ -16,20 +16,20 @@ namespace Donut
         
         const auto& settings = SettingsManager::get_settings_const();
         
-        m_selected_api   = (settings.graphics.render_api == "Vulkan") ? RendererAPI::API::Vulkan : RendererAPI::API::OpenGL;
-        m_selected_theme = (settings.graphics.selected_theme == "Light") ? 1 : 
-                          (settings.graphics.selected_theme == "Blue") ? 2 : 0;
-        m_target_fps     = settings.simulation.target_fps;
-        m_compute_height = settings.simulation.compute_height;
-        m_max_steps_moving = settings.simulation.max_steps_moving;
-        m_max_steps_static = settings.simulation.max_steps_static;
-        m_early_exit_distance = settings.simulation.early_exit_distance;
-        m_gravity_enabled = settings.simulation.gravity_enabled;
-        m_v_sync_enabled = settings.graphics.v_sync_enabled;
-        m_show_fps = settings.graphics.show_fps;
+        m_selected_api            = (settings.graphics.render_api == "Vulkan") ? RendererAPI::API::Vulkan : RendererAPI::API::OpenGL;
+        m_selected_theme          = (settings.graphics.selected_theme == "Light") ? 1 : 
+                                   (settings.graphics.selected_theme == "Blue") ? 2 : 0;
+        m_target_fps              = settings.simulation.target_fps;
+        m_compute_height          = settings.simulation.compute_height;
+        m_max_steps_moving         = settings.simulation.max_steps_moving;
+        m_max_steps_static         = settings.simulation.max_steps_static;
+        m_early_exit_distance      = settings.simulation.early_exit_distance;
+        m_gravity_enabled         = settings.simulation.gravity_enabled;
+        m_v_sync_enabled           = settings.graphics.v_sync_enabled;
+        m_show_fps                = settings.graphics.show_fps;
         m_show_performance_metrics = settings.graphics.show_performance_metrics;
-        m_show_debug_info = settings.graphics.show_debug_info;
-        m_enable_anti_aliasing = settings.graphics.enable_anti_aliasing;
+        m_show_debug_info          = settings.graphics.show_debug_info;
+        m_enable_anti_aliasing     = settings.graphics.enable_anti_aliasing;
     }
     
     void ConfigState::on_exit()
@@ -52,7 +52,7 @@ namespace Donut
     
     void ConfigState::on_render()
     {
-        Renderer::set_clear_color({ 0.05f, 0.05f, 0.1f, 1.0f });
+        Renderer::set_clear_color({ 0.1f, 0.1f, 0.1f, 1.0f });
         Renderer::clear();
     }
     
@@ -104,6 +104,7 @@ namespace Donut
                 if (is_selected)
                     ImGui::SetItemDefaultFocus();
             }
+            
             ImGui::EndCombo();
         }
         
@@ -215,7 +216,7 @@ namespace Donut
         ImGui::Separator();
         ImGui::Spacing();
 
-        float button_width = (ImGui::GetWindowWidth() - 100) / 5.0f;
+        float button_width = (ImGui::GetWindowWidth() - 120) / 6.0f;
         
         if (ImGui::Button("Start Simulation", ImVec2(button_width, 35)))
         {
@@ -224,6 +225,13 @@ namespace Donut
         }
         
         ImGui::SameLine();
+        if (ImGui::Button("World Builder", ImVec2(button_width, 35)))
+        {
+            apply_settings();
+            Application::get().get_state_manager().switch_to_state("WorldBuilder");
+        }
+        
+        ImGui::SameLine();
         if (ImGui::Button("Reset to Defaults", ImVec2(button_width, 35)))
             reset_to_defaults();
         
diff --git a/src/states/world_builder_state.cpp b/src/states/world_builder_state.cpp
new file mode 100644
index 0000000..16b7866
--- /dev/null
+++ b/src/states/world_builder_state.cpp
@@ -0,0 +1,674 @@
+#include "world_builder_state.h"
+
+#include "core/application.h"
+#include "core/window.h"
+
+#include "rendering/renderer.h"
+#include "rendering/shader.h"
+#include "rendering/vertex_array.h"
+#include "rendering/vertex_buffer.h"
+#include "rendering/index_buffer.h"
+#include "rendering/texture.h"
+
+#include <imgui.h>
+#include <ImGuizmo.h>
+#include <GLFW/glfw3.h>
+
+#include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
+#include <fstream>
+#include <sstream>
+#include <limits>
+
+#define _USE_MATH_DEFINES
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+namespace Donut
+{
+    void WorldBuilderState::on_enter()
+    {
+        DONUT_INFO("Entering World Builder State");
+        
+        ImGuizmo::Enable(true);
+
+        m_camera.set_camera_mode(CameraMode::Orbital);
+        m_camera.set_orbital_target(glm::vec3(0.0f, 0.0f, 0.0f));
+        m_camera.set_orbital_radius(15.0f);
+        m_camera.set_orbital_limits(2.0f, 200.0f);
+        m_camera.set_orbital_speed(0.01f);
+        m_camera.set_zoom_speed(2.0f);
+        m_camera.set_azimuth(0.0f);
+        m_camera.set_elevation(static_cast<float>(M_PI) / 3.0f);
+        m_camera.update_orbital();
+        
+        Material default_material(glm::vec3(0.8f, 0.2f, 0.2f), 0.5f, 0.0f);
+        Object sphere1(glm::vec3(-3.0f, 0.0f, 0.0f), 1.0f, default_material);
+        m_scene.objs.push_back(sphere1);
+        
+        Material material2(glm::vec3(0.2f, 0.8f, 0.2f), 0.3f, 0.0f);
+        Object sphere2(glm::vec3(3.0f, 0.0f, 0.0f), 1.5f, material2);
+        m_scene.objs.push_back(sphere2);
+        
+        Material material3(glm::vec3(0.2f, 0.2f, 0.8f), 0.7f, 0.0f);
+        Object sphere3(glm::vec3(0.0f, 2.0f, 0.0f), 0.8f, material3);
+        m_scene.objs.push_back(sphere3);
+        
+        m_initialized = true;
+    }
+    
+    void WorldBuilderState::on_exit()
+    {
+        DONUT_INFO("Exiting World Builder State");
+    }
+    
+    void WorldBuilderState::on_update(float delta_time)
+    {
+        if (m_camera_dragging && 
+            !ImGuizmo::IsUsing())
+        {
+            GLFWwindow* window = static_cast<GLFWwindow*>(Application::get().get_window().get_native_window());
+            double xpos, ypos;
+            glfwGetCursorPos(window, &xpos, &ypos);
+            
+            glm::vec2 current_mouse_pos(xpos, ypos);
+            glm::vec2 delta = current_mouse_pos - m_last_mouse_pos;
+            
+            float sensitivity    = 0.005f;
+            float azimuth_delta   = delta.x * sensitivity;
+            float elevation_delta = -delta.y * sensitivity;
+            
+            float new_azimuth   = m_camera.get_azimuth() + azimuth_delta;
+            float new_elevation = m_camera.get_elevation() + elevation_delta;
+            
+            new_elevation = glm::clamp(new_elevation, 0.01f, static_cast<float>(M_PI) - 0.01f);
+            
+            m_camera.set_azimuth(new_azimuth);
+            m_camera.set_elevation(new_elevation);
+            m_camera.update_orbital();
+            
+            m_last_mouse_pos = current_mouse_pos;
+        }
+    }
+    
+    void WorldBuilderState::on_render()
+    {
+        RenderCommand::set_clear_color(glm::vec4(0.1f, 0.1f, 0.1f, 1.0f));
+        RenderCommand::clear();
+        render_scene();
+    }
+    
+    void WorldBuilderState::on_event(Event& event)
+    {
+        EventDispatcher dispatcher(event);
+        
+        dispatcher.dispatch<MouseButtonPressedEvent>([this](MouseButtonPressedEvent& e) 
+        {
+            if (e.get_mouse_button() == GLFW_MOUSE_BUTTON_LEFT)
+            {
+                if (ImGuizmo::IsUsing() || 
+                    ImGuizmo::IsOver())
+                    return false;
+                
+                GLFWwindow* window = static_cast<GLFWwindow*>(Application::get().get_window().get_native_window());
+                double xpos, ypos;
+                glfwGetCursorPos(window, &xpos, &ypos);
+                
+                int width, height;
+                glfwGetFramebufferSize(window, &width, &height);
+                
+                float ndc_x = (2.0f * xpos) / width - 1.0f;
+                float ndc_y = 1.0f - (2.0f * ypos) / height;
+                
+                glm::vec4 ray_start_ndc(ndc_x, ndc_y, -1.0f, 1.0f);
+                glm::vec4 ray_end_ndc(ndc_x, ndc_y, 0.0f, 1.0f);
+                
+                glm::mat4 inv_vp          = glm::inverse(m_camera.get_projection_matrix() * m_camera.get_view_matrix());
+                glm::vec4 ray_start_world = inv_vp * ray_start_ndc;
+                glm::vec4 ray_end_world   = inv_vp * ray_end_ndc;
+                
+                ray_start_world /= ray_start_world.w;
+                ray_end_world   /= ray_end_world.w;
+                
+                glm::vec3 ray_dir    = glm::normalize(glm::vec3(ray_end_world - ray_start_world));
+                glm::vec3 ray_origin = glm::vec3(ray_start_world);
+                
+                float closest_distance  = std::numeric_limits<float>::max();
+                int closest_object_index = -1;
+                
+                for (size_t i = 0; i < m_scene.objs.size(); ++i)
+                {
+                    const Object& obj = m_scene.objs[i];
+                    
+                    glm::vec3 oc       = ray_origin - obj.m_centre;
+                    float a            = glm::dot(ray_dir, ray_dir);
+                    float b            = 2.0f * glm::dot(oc, ray_dir);
+                    float c            = glm::dot(oc, oc) - obj.m_radius * obj.m_radius;
+                    float discriminant = b * b - 4 * a * c;
+                    
+                    if (discriminant > 0)
+                    {
+                        float t1 = (-b - sqrt(discriminant)) / (2.0f * a);
+                        float t2 = (-b + sqrt(discriminant)) / (2.0f * a);
+                        
+                        if (t1 > 0 && t1 < closest_distance)
+                        {
+                            closest_distance = t1;
+                            closest_object_index = static_cast<int>(i);
+                        }
+                        else if (t2 > 0 && t2 < closest_distance)
+                        {
+                            closest_distance = t2;
+                            closest_object_index = static_cast<int>(i);
+                        }
+                    }
+                }
+                
+                if (closest_object_index >= 0)
+                {
+                    m_selected_object_index = closest_object_index;
+                    DONUT_INFO("Selected object {}", closest_object_index);
+                    return true;
+                }
+                else
+                {
+                    m_camera_dragging = true;
+                    m_last_mouse_pos = glm::vec2(xpos, ypos);
+                }
+                
+                return true;
+            }
+            return false;
+        });
+        
+        dispatcher.dispatch<MouseButtonReleasedEvent>([this](MouseButtonReleasedEvent& e) 
+        {
+            if (e.get_mouse_button() == GLFW_MOUSE_BUTTON_LEFT)
+            {
+                if (!ImGuizmo::IsUsing())
+                    m_camera_dragging = false;
+                return true;
+            }
+
+            return false;
+        });
+        
+        dispatcher.dispatch<WindowResizeEvent>([this](WindowResizeEvent& e)
+        {
+            int new_width = e.get_width();
+            int new_height = e.get_height();
+            if (new_width > 0 && new_height > 0)
+            {
+                float aspect = static_cast<float>(new_width) / static_cast<float>(new_height);
+                m_camera.set_projection(45.0f, aspect, 0.1f, 1000.0f);
+            }
+            return false;
+        });
+        
+        dispatcher.dispatch<MouseScrolledEvent>([this](MouseScrolledEvent& e) 
+        {
+            float zoom_speed = 0.1f;
+            float zoom_delta = e.get_y_offset() * zoom_speed;
+            
+            double current_radius = m_camera.get_orbital_radius();
+            double new_radius = current_radius - zoom_delta * current_radius * 0.1f;
+            
+            double min_radius = 2.0f;
+            double max_radius = 200.0f;
+            new_radius        = glm::clamp(new_radius, min_radius, max_radius);
+            
+            m_camera.set_orbital_radius(new_radius);
+            m_camera.update_orbital();
+
+            return true;
+        });
+        
+        dispatcher.dispatch<KeyPressedEvent>([this](KeyPressedEvent& e) 
+        {
+            if (m_selected_object_index >= 0 && 
+                m_selected_object_index < static_cast<int>(m_scene.objs.size()))
+            {
+                switch (e.get_key_code())
+                {
+                    case GLFW_KEY_W:
+                        m_gizmo_operation = ImGuizmo::TRANSLATE;
+                        return true;
+                    case GLFW_KEY_E:
+                        m_gizmo_operation = ImGuizmo::ROTATE;
+                        return true;
+                    case GLFW_KEY_R:
+                        m_gizmo_operation = ImGuizmo::SCALE;
+                        return true;
+                }
+            }
+            return false;
+        });
+    }
+    
+    void WorldBuilderState::on_im_ui_render()
+    {
+        GLFWwindow* window = static_cast<GLFWwindow*>(Application::get().get_window().get_native_window());
+        int width, height;
+        glfwGetFramebufferSize(window, &width, &height);
+     
+        ImGuiViewport* vp = ImGui::GetMainViewport();
+        ImGuizmo::SetRect(vp->Pos.x, vp->Pos.y, vp->Size.x, vp->Size.y);
+        
+        ImGui::SetNextWindowSize(ImVec2(400, 600), ImGuiCond_FirstUseEver);
+        ImGui::SetNextWindowPos(ImVec2(10, 10), ImGuiCond_FirstUseEver);
+        
+        ImGui::Begin("World Builder", nullptr, ImGuiWindowFlags_NoCollapse);
+        
+        ImGui::PushFont(ImGui::GetIO().Fonts->Fonts[0]);
+        ImGui::TextColored(ImVec4(0.8f, 0.8f, 1.0f, 1.0f), "World Builder");
+        ImGui::PopFont();
+        ImGui::Separator();
+        
+         if (ImGui::CollapsingHeader("Scene Info", &m_show_scene_info))
+         {
+            ImGui::Text("Objects in scene: %zu", m_scene.objs.size());
+            
+            ImGui::Separator();
+            ImGui::TextColored(ImVec4(0.9f, 0.9f, 1.0f, 1.0f), "Camera Info:");
+            
+            glm::vec3 camera_pos = m_camera.get_orbital_position();
+            glm::vec3 target = m_camera.get_orbital_target();
+            
+            ImGui::Text("Position: (%.2f, %.2f, %.2f)", camera_pos.x, camera_pos.y, camera_pos.z);
+            ImGui::Text("Target: (%.2f, %.2f, %.2f)", target.x, target.y, target.z);
+            ImGui::Text("Distance: %.2f", m_camera.get_orbital_radius());
+            ImGui::Text("Azimuth: %.1f°", glm::degrees(m_camera.get_azimuth()));
+            ImGui::Text("Elevation: %.1f°", glm::degrees(m_camera.get_elevation()));
+            
+            ImGui::Separator();
+            
+            if (ImGui::Button("Reset Camera"))
+            {
+                m_camera.set_orbital_radius(15.0f);
+                m_camera.set_azimuth(0.0f);
+                m_camera.set_elevation(static_cast<float>(M_PI) / 3.0f);
+                m_camera.set_orbital_target(glm::vec3(0.0f, 0.0f, 0.0f));
+                m_camera.update_orbital();
+            }
+            
+            ImGui::SameLine();
+            if (ImGui::Button("Clear Scene"))
+                clear_scene();
+            
+            ImGui::SameLine();
+            if (ImGui::Button("Focus on Objects"))
+            {
+                if (!m_scene.objs.empty())
+                {
+                    glm::vec3 center(0.0f);
+                    for (const auto& obj : m_scene.objs)
+                        center += obj.m_centre;
+                    center /= static_cast<float>(m_scene.objs.size());
+                    m_camera.set_orbital_target(center);
+                    m_camera.update_orbital();
+                }
+            }
+        }
+        
+        ImGui::Spacing();
+        
+        if (ImGui::CollapsingHeader("Create Object", &m_show_object_creator))
+        {
+            ImGui::TextColored(ImVec4(0.9f, 0.9f, 1.0f, 1.0f), "New Sphere");
+            ImGui::Separator();
+            
+            ImGui::Text("Position:");
+            ImGui::DragFloat3("##Position", &m_new_object_position.x, 0.1f);
+            
+            ImGui::Text("Radius:");
+            ImGui::DragFloat("##Radius", &m_new_object_radius, 0.1f, 0.1f, 10.0f);
+            
+            ImGui::Text("Color:");
+            ImGui::ColorEdit3("##Color", &m_new_object_color.x);
+            
+            ImGui::Text("Specular:");
+            ImGui::SliderFloat("##Specular", &m_new_object_specular, 0.0f, 1.0f);
+            
+            ImGui::Text("Emission:");
+            ImGui::SliderFloat("##Emission", &m_new_object_emission, 0.0f, 1.0f);
+            
+            ImGui::Spacing();
+            
+            if (ImGui::Button("Add Sphere", ImVec2(ImGui::GetWindowWidth() - 20, 30)))
+                add_sphere();
+        }
+        
+        ImGui::Spacing();
+        
+        if (ImGui::CollapsingHeader("Scene Objects", &m_show_object_list))
+        {
+            if (m_scene.objs.empty())
+                ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f), "No objects in scene");
+            else
+            {
+                for (size_t i = 0; i < m_scene.objs.size(); ++i)
+                {
+                    Object& obj = m_scene.objs[i];
+                    
+                    ImGui::PushID(static_cast<int>(i));
+                    
+                    bool is_selected = (m_selected_object_index == static_cast<int>(i));
+                    if (ImGui::Selectable(("Sphere " + std::to_string(i)).c_str(), is_selected))
+                        m_selected_object_index = static_cast<int>(i);
+                    
+                    if (is_selected)
+                    {
+                        ImGui::SameLine();
+                        if (ImGui::Button("Remove"))
+                        {
+                            remove_selected_object();
+                        }
+                        
+                        ImGui::Text("Position: (%.2f, %.2f, %.2f)", 
+                                   obj.m_centre.x, obj.m_centre.y, obj.m_centre.z);
+                        ImGui::Text("Radius: %.2f", obj.m_radius);
+                        ImGui::Text("Color: (%.2f, %.2f, %.2f)", 
+                                   obj.m_material.m_color.x, obj.m_material.m_color.y, obj.m_material.m_color.z);
+                    }
+                    
+                    ImGui::PopID();
+                }
+            }
+        }
+         
+        if (ImGui::CollapsingHeader("Gizmo Controls", &m_show_gizmo_controls))
+        {
+            ImGui::TextColored(ImVec4(0.9f, 0.9f, 1.0f, 1.0f), "Gizmo Operation:");
+            
+            if (ImGui::RadioButton("Translate", m_gizmo_operation == ImGuizmo::TRANSLATE))
+                m_gizmo_operation = ImGuizmo::TRANSLATE;
+            ImGui::SameLine();
+            if (ImGui::RadioButton("Rotate", m_gizmo_operation == ImGuizmo::ROTATE))
+                m_gizmo_operation = ImGuizmo::ROTATE;
+            ImGui::SameLine();
+            if (ImGui::RadioButton("Scale", m_gizmo_operation == ImGuizmo::SCALE))
+                m_gizmo_operation = ImGuizmo::SCALE;
+            
+            ImGui::Spacing();
+            ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f), "Hotkeys:");
+            ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f), "W = Translate, E = Rotate, R = Scale");
+        }
+        
+        ImGui::Spacing();
+        ImGui::Separator();
+        ImGui::Spacing();
+        
+        float button_width = (ImGui::GetWindowWidth() - 30) / 2.0f;
+        
+        if (ImGui::Button("Save Scene", ImVec2(button_width, 30)))
+            save_scene();
+        
+        ImGui::SameLine();
+        if (ImGui::Button("Load Scene", ImVec2(button_width, 30)))
+            load_scene();
+        
+        ImGui::Spacing();
+        
+        if (ImGui::Button("Back to Config", ImVec2(ImGui::GetWindowWidth() - 20, 30)))
+            Application::get().get_state_manager().switch_to_state("Config");
+        
+        ImGui::Spacing();
+        ImGui::Separator();
+        ImGui::TextColored(ImVec4(0.5f, 0.5f, 0.5f, 1.0f), "Camera: Left mouse = rotate, Scroll = zoom");
+        ImGui::TextColored(ImVec4(0.5f, 0.5f, 0.5f, 1.0f), "Gizmo: W=Translate, E=Rotate, R=Scale");
+        
+        ImGui::End();
+        
+        if (m_selected_object_index >= 0 && 
+            m_selected_object_index < static_cast<int>(m_scene.objs.size()))
+        {
+            glm::mat4 view       = m_camera.get_view_matrix();
+            glm::mat4 projection = m_camera.get_projection_matrix();
+            
+            Object& selected_obj = m_scene.objs[m_selected_object_index];
+            
+            glm::mat4 object_transform = glm::mat4(1.0f);
+                      object_transform = glm::translate(object_transform, selected_obj.m_centre);
+                      object_transform = glm::scale(object_transform, glm::vec3(selected_obj.m_radius));
+            
+            DONUT_INFO("Object position: ({}, {}, {})", selected_obj.m_centre.x, selected_obj.m_centre.y, selected_obj.m_centre.z);
+            glm::vec3 camera_pos = m_camera.get_orbital_position();
+            DONUT_INFO("Camera position: ({}, {}, {})", camera_pos.x, camera_pos.y, camera_pos.z);
+            
+            glm::vec3 view_translation = glm::vec3(view[3][0], view[3][1], view[3][2]);
+            DONUT_INFO("View translation: ({}, {}, {})", view_translation.x, view_translation.y, view_translation.z);
+            
+            ImGuizmo::SetDrawlist(ImGui::GetForegroundDrawList());
+            if (ImGuizmo::Manipulate(glm::value_ptr(view), glm::value_ptr(projection), 
+                                   m_gizmo_operation, m_gizmo_mode, 
+                                   glm::value_ptr(object_transform), 
+                                   nullptr, nullptr))
+            {
+                glm::vec3 new_position = glm::vec3(object_transform[3][0], object_transform[3][1], object_transform[3][2]);
+                selected_obj.m_centre = new_position;
+                
+                glm::vec3 scale = glm::vec3(
+                    glm::length(glm::vec3(object_transform[0])),
+                    glm::length(glm::vec3(object_transform[1])),
+                    glm::length(glm::vec3(object_transform[2]))
+                );
+                selected_obj.m_radius = (scale.x + scale.y + scale.z) / 3.0f;
+                
+                DONUT_INFO("Matrix [3]: ({}, {}, {}, {})", object_transform[3][0], object_transform[3][1], object_transform[3][2], object_transform[3][3]);
+                DONUT_INFO("New position: ({}, {}, {})", new_position.x, new_position.y, new_position.z);
+            }
+        }
+     }
+    
+    void WorldBuilderState::add_sphere()
+    {
+        Material material(m_new_object_color, m_new_object_specular, m_new_object_emission);
+        Object   sphere(m_new_object_position, m_new_object_radius, material);
+        m_scene.objs.push_back(sphere);
+        
+        m_new_object_position = glm::vec3(0.0f, 0.0f, 0.0f);
+        m_new_object_radius   = 1.0f;
+        m_new_object_color    = glm::vec3(1.0f, 1.0f, 1.0f);
+        m_new_object_specular = 0.5f;
+        m_new_object_emission = 0.0f;
+        
+        DONUT_INFO("Added sphere to scene");
+    }
+    
+    void WorldBuilderState::remove_selected_object()
+    {
+        if (m_selected_object_index >= 0 && m_selected_object_index < static_cast<int>(m_scene.objs.size()))
+        {
+            m_scene.objs.erase(m_scene.objs.begin() + m_selected_object_index);
+            m_selected_object_index = -1;
+            DONUT_INFO("Removed object from scene");
+        }
+    }
+    
+    void WorldBuilderState::clear_scene()
+    {
+        m_scene.objs.clear();
+        m_selected_object_index = -1;
+        DONUT_INFO("Cleared scene");
+    }
+    
+    void WorldBuilderState::save_scene()
+    {
+        std::ofstream file("scene.txt");
+
+        if (file.is_open())
+        {
+            file << m_scene.objs.size() << std::endl;
+            for (const auto& obj : m_scene.objs)
+            {
+                file << obj.m_centre.x << " " << obj.m_centre.y << " " << obj.m_centre.z << " ";
+                file << obj.m_radius << " ";
+                file << obj.m_material.m_color.x << " " << obj.m_material.m_color.y << " " << obj.m_material.m_color.z << " ";
+                file << obj.m_material.m_specular << " " << obj.m_material.m_emission << std::endl;
+            }
+            file.close();
+            DONUT_INFO("Scene saved to scene.txt");
+        }
+        else
+            DONUT_ERROR("Failed to save scene");
+    }
+    
+    void WorldBuilderState::load_scene()
+    {
+        std::ifstream file("scene.txt");
+        if (file.is_open())
+        {
+            m_scene.objs.clear();
+            m_selected_object_index = -1;
+            
+            size_t object_count;
+            file >> object_count;
+            
+            for (size_t i = 0; i < object_count; ++i)
+            {
+                glm::vec3 position;
+                float radius;
+                glm::vec3 color;
+                float specular, emission;
+                
+                file >> position.x >> position.y >> position.z;
+                file >> radius;
+                file >> color.x >> color.y >> color.z;
+                file >> specular >> emission;
+                
+                Material material(color, specular, emission);
+                Object   sphere(position, radius, material);
+                m_scene.objs.push_back(sphere);
+            }
+            
+            file.close();
+            DONUT_INFO("Scene loaded from scene.txt");
+        }
+        else
+            DONUT_ERROR("Failed to load scene");
+    }
+    
+    void WorldBuilderState::render_scene()
+    {
+        GLFWwindow* window = static_cast<GLFWwindow*>(Application::get().get_window().get_native_window());
+        int width, height;
+        glfwGetFramebufferSize(window, &width, &height);
+
+        RenderCommand::set_viewport(0, 0, width, height);
+        RenderCommand::enable_depth_test();
+        
+        static Ref<VertexArray> sphere_vao = nullptr;
+        static Ref<Shader> sphere_shader   = Ref<Shader>(Shader::create("assets/shaders/sphere.glsl"));
+        
+        if (!sphere_vao)
+        {
+            std::vector<float> vertices;
+            std::vector<uint32_t> indices;
+            
+            const int segments = 32;
+            const int rings = 16;
+            
+            for (int ring = 0; ring <= rings; ++ring)
+            {
+                float phi = static_cast<float>(M_PI) * ring / rings;
+                float sin_phi = sin(phi);
+                float cos_phi = cos(phi);
+                
+                for (int segment = 0; segment <= segments; ++segment)
+                {
+                    float theta = 2.0f * static_cast<float>(M_PI) * segment / segments;
+                    float sin_theta = sin(theta);
+                    float cos_theta = cos(theta);
+                    
+                    float x = cos_theta * sin_phi;
+                    float y = cos_phi;
+                    float z = sin_theta * sin_phi;
+                    
+                    float nx = x;
+                    float ny = y;
+                    float nz = z;
+                    
+                    vertices.push_back(x);
+                    vertices.push_back(y);
+                    vertices.push_back(z);
+                    vertices.push_back(nx);
+                    vertices.push_back(ny);
+                    vertices.push_back(nz);
+                }
+            }
+            
+            for (int ring = 0; ring < rings; ++ring)
+            {
+                for (int segment = 0; segment < segments; ++segment)
+                {
+                    uint32_t first = ring * (segments + 1) + segment;
+                    uint32_t second = first + segments + 1;
+                    
+                    indices.push_back(first);
+                    indices.push_back(second);
+                    indices.push_back(first + 1);
+                    
+                    indices.push_back(second);
+                    indices.push_back(second + 1);
+                    indices.push_back(first + 1);
+                }
+            }
+            
+            auto vertex_buffer = Ref<VertexBuffer>(VertexBuffer::create(vertices.data(), static_cast<uint32_t>(vertices.size() * sizeof(float))));
+            VertexBufferLayout layout;
+            layout.push<float>(3);
+            layout.push<float>(3);
+            vertex_buffer->set_layout(layout);
+            
+            auto index_buffer = Ref<IndexBuffer>(IndexBuffer::create(indices.data(), static_cast<uint32_t>(indices.size())));
+            
+            sphere_vao = Ref<VertexArray>(VertexArray::create());
+            sphere_vao->add_vertex_buffer(vertex_buffer);
+            sphere_vao->set_index_buffer(index_buffer);
+        }
+        
+        glm::mat4 view           = m_camera.get_view_matrix();
+        glm::mat4 projection     = m_camera.get_projection_matrix();
+        glm::mat4 view_projection = projection * view;
+        
+        glm::vec3 light_pos  = m_scene.m_light_pos;
+        glm::vec3 camera_pos = m_camera.get_orbital_position();
+        
+        sphere_shader->bind();
+        sphere_shader->set_mat4("u_ViewProjection", view_projection);
+        sphere_shader->set_float3("u_LightPos", light_pos);
+        sphere_shader->set_float3("u_CameraPos", camera_pos);
+        
+        for (size_t i = 0; i < m_scene.objs.size(); ++i)
+        {
+            const auto& obj = m_scene.objs[i];
+            
+            glm::mat4 transform = glm::translate(glm::mat4(1.0f), obj.m_centre);
+                      transform = glm::scale(transform, glm::vec3(obj.m_radius));
+            
+            sphere_shader->set_mat4("u_Transform", transform);
+            
+            if (m_selected_object_index == static_cast<int>(i))
+            {
+                glm::vec3 highlight_color = obj.m_material.m_color * 1.5f;
+                highlight_color = glm::clamp(highlight_color, 0.0f, 1.0f);
+                sphere_shader->set_float3("u_Color", highlight_color);
+                sphere_shader->set_float("u_Emission", 0.2f);
+            }
+            else
+            {
+                sphere_shader->set_float3("u_Color", obj.m_material.m_color);
+                sphere_shader->set_float("u_Emission", obj.m_material.m_emission);
+            }
+            
+            sphere_shader->set_float("u_Specular", obj.m_material.m_specular);
+            
+            sphere_vao->bind();
+            RenderCommand::draw_indexed(sphere_vao);
+        }
+        
+        RenderCommand::disable_depth_test();
+    }
+};
diff --git a/src/states/world_builder_state.h b/src/states/world_builder_state.h
new file mode 100644
index 0000000..c587fbe
--- /dev/null
+++ b/src/states/world_builder_state.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include "core/camera.h"
+#include "core/state.h"
+#include "core/event.h"
+#include "core/log.h"
+
+#include "engine/scene.h"
+#include "engine/object.h"
+
+#include "rendering/renderer.h"
+#include "rendering/shader.h"
+#include "rendering/vertex_array.h"
+
+#include <imgui.h>
+#include <ImGuizmo.h>
+
+#include <vector>
+#include <memory>
+
+namespace Donut
+{
+    class WorldBuilderState
+        : public State
+    {
+    public:
+        ~WorldBuilderState() = default;
+        
+        void on_enter()                 override;
+        void on_exit()                  override;
+        void on_update(float delta_time) override;
+        void on_render()                override;
+        void on_im_ui_render()            override;
+        void on_event(Event& event)     override;
+    private:
+        void add_sphere();
+        void remove_selected_object();
+        void clear_scene();
+        void save_scene();
+        void load_scene();
+        void render_scene();
+    private:
+        Scene  m_scene;
+        Camera m_camera;
+        bool   m_initialized = false;
+        
+        glm::vec3 m_new_object_position = glm::vec3(0.0f, 0.0f, 0.0f);
+        float     m_new_object_radius   = 1.0f;
+        glm::vec3 m_new_object_color    = glm::vec3(1.0f, 1.0f, 1.0f);
+        float     m_new_object_specular = 0.5f;
+        float     m_new_object_emission = 0.0f;
+        
+        int       m_selected_object_index = -1;
+        bool      m_camera_dragging      = false;
+        glm::vec2 m_last_mouse_pos        = glm::vec2(0.0f, 0.0f);
+        
+        ImGuizmo::OPERATION m_gizmo_operation = ImGuizmo::TRANSLATE;
+        ImGuizmo::MODE      m_gizmo_mode      = ImGuizmo::LOCAL;
+        
+        bool m_show_object_list    = true;
+        bool m_show_object_creator = true;
+        bool m_show_scene_info     = true;
+        bool m_show_gizmo_controls = true;
+    };
+};