Object Picking (#82)

* Add picking shader program for object selection

* Integrate picking shader into render pipeline manager

* Add picking draw logic to entities, groups and scene

* Implement mouse picking and framebuffer setup in SceneWindow

* Add drawRaw method to Model for picking rendering

* Display selected entity ID in UI

* Expose window handle and add support for ImGui integration

* (maybe) fix lint warning

* (maybe p.2) fix lint warning

* (maybe p.3) fix lint error

* (maybe p.4) fix lint error

* format fix

* Simplify object picking

* Add object picking to third person camera

* Fix override error lint

* Fix useStlAlgorithm error lint

* Fix bug when camera is not third person

* Add entity name support to picking

* Add entity name to menu

* Cleanup object picking

* Add name generation to Solar System

* Regenerate Solar System

Sphere was updated as well

---------

Co-authored-by: voidbert <humbertogilgomes@protonmail.com>

Author: saraazevedolopes

include/engine/render/Framebuffer.hpp

@@ -0,0 +1,36 @@
+/// Copyright 2025 Ana Oliveira, Humberto Gomes, Mariana Rocha, Sara Lopes
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#include <array>
+#include <cstdint>
+#include <glad/glad.h>
+
+namespace engine::render {
+
+class Framebuffer {
+private:
+    GLuint fbo, colorTexture, depthRenderBuffer;
+    int width, height;
+
+public:
+    Framebuffer(int _width, int _height);
+    Framebuffer(const Framebuffer &framebuffer) = delete;
+    Framebuffer(Framebuffer &&framebuffer) = delete;
+    ~Framebuffer();
+
+    void use();
+    std::array<uint8_t, 3> sample(int x, int y);
+};
+
+}

include/engine/scene/Entity.hpp

@@ -36,6 +36,7 @@ class Entity {
     render::BoundingSphere boundingSphere;
     std::shared_ptr<render::Texture> texture;
     Material material;
+    std::string name;
 
 public:
     Entity(const tinyxml2::XMLElement *modelElement,
@@ -48,6 +49,12 @@ class Entity {
     void updateBoundingSphere(const glm::mat4 &worldTransform);
     const render::BoundingSphere &getBoundingSphere() const;
     const render::NormalsPreview &getNormalsPreview() const;
+    const std::string &getName() const;
+
+    void drawSolidColor(render::RenderPipelineManager &pipelineManager,
+                        const glm::mat4 &fullMatrix,
+                        const glm::vec4 &color,
+                        bool fillPolygons) const;
 
     void draw(render::RenderPipelineManager &pipelineManager,
               const glm::mat4 &fullMatrix,

include/engine/scene/Group.hpp

@@ -16,6 +16,7 @@
 
 #include <filesystem>
 #include <glm/mat4x4.hpp>
+#include <glm/vec4.hpp>
 #include <memory>
 #include <string>
 #include <tinyxml2.h>
@@ -62,6 +63,12 @@ class Group {
                         const glm::mat4 &worldtransform,
                         bool fillPolygons) const;
 
+    int drawForPicking(render::RenderPipelineManager &pipelineManager,
+                       const camera::Camera &camera,
+                       const glm::mat4 &worldTransform,
+                       std::unordered_map<int, std::string> &idToName,
+                       int currentId) const;
+
 private:
     const render::BoundingSphere &getBoundingSphere() const;
     void updateBoundingSphere(const glm::mat4 &worldTransform);

include/engine/scene/Scene.hpp

@@ -16,6 +16,7 @@
 
 #include <memory>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 #include "engine/render/Axis.hpp"
@@ -58,6 +59,9 @@ class Scene {
              bool showBoundingSpheres,
              bool showAnimationLines,
              bool showNormals) const;
+
+    void drawForPicking(render::RenderPipelineManager &pipelineManager,
+                        std::unordered_map<int, std::string> &idToName) const;
 };
 
 }

include/engine/scene/camera/Camera.hpp

@@ -18,6 +18,7 @@
 #include <glm/mat4x4.hpp>
 #include <glm/vec2.hpp>
 #include <glm/vec3.hpp>
+#include <unordered_map>
 
 #include "engine/render/BoundingSphere.hpp"
 #include "engine/render/RenderPipelineManager.hpp"
@@ -60,6 +61,9 @@ class Camera {
                                      bool showNormals) const;
     virtual int drawShadedParts(render::RenderPipelineManager &pipelineManager,
                                 bool fillPolygons) const;
+    virtual int drawForPicking(render::RenderPipelineManager &pipelineManager,
+                               std::unordered_map<int, std::string> &idToName,
+                               int currentId) const;
 
     bool isInFrustum(const render::BoundingSphere &sphere) const;
 

include/engine/scene/camera/ThirdPersonCamera.hpp

@@ -17,6 +17,7 @@
 #include <glm/vec2.hpp>
 #include <glm/vec3.hpp>
 #include <memory>
+#include <unordered_map>
 
 #include "engine/scene/camera/OrbitalCamera.hpp"
 #include "engine/scene/Group.hpp"
@@ -49,6 +50,9 @@ class ThirdPersonCamera : public OrbitalCamera {
                                      bool showNormals) const override;
     virtual int drawShadedParts(render::RenderPipelineManager &pipelineManager,
                                 bool fillPolygons) const override;
+    virtual int drawForPicking(render::RenderPipelineManager &pipelineManager,
+                               std::unordered_map<int, std::string> &idToName,
+                               int currentId) const override;
 
 protected:
     virtual void updateWithMotion() override;

include/engine/window/SceneWindow.hpp

@@ -29,6 +29,7 @@ class SceneWindow : public Window {
     scene::camera::CameraController cameraController;
 
     UI ui;
+    std::string selectedEntity;
     bool showUI;
 
 public:
@@ -41,6 +42,7 @@ class SceneWindow : public Window {
     void onRender() override;
     void onResize(int _width, int _height) override;
     void onKeyEvent(int key, int action) override;
+    void onMouseButtonEvent(int button, int action) override;
 };
 
 }

include/engine/window/UI.hpp

@@ -29,11 +29,11 @@ class UI {
         showNormals;
 
 public:
-    UI(Window &window, scene::camera::Camera &_camera, int _entityCount);
+    UI(const Window &window, scene::camera::Camera &_camera, int _entityCount);
     ~UI();
 
     bool isCapturingKeyboard() const;
-    void draw(int renderedEntities);
+    void draw(int renderedEntities, const std::string &selectedEntity);
 
     bool shouldFillPolygons() const;
     bool shouldCullBackFaces() const;

include/engine/window/Window.hpp

@@ -35,13 +35,14 @@ class Window {
 
     int getWidth() const;
     int getHeight() const;
-    GLFWwindow *getHandle();
+    GLFWwindow *getHandle() const;
 
 protected:
     virtual void onUpdate(float time, float timeElapsed) = 0;
     virtual void onRender() = 0;
     virtual void onResize(int _width, int _height) = 0;
     virtual void onKeyEvent(int key, int action) = 0;
+    virtual void onMouseButtonEvent(int button, int action) = 0;
 };
 
 }