ThreeLab/Engine/Engine.h

#ifndef ENGINE_H
#define ENGINE_H

#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include "imgui_impl_glfw.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

class Engine {
public:
    // Main window.
    static GLFWwindow* window;

    // Initializes GLFW, GLEW, and sets up the main window and offscreen framebuffer.
    static bool Init();

    // Returns the main GLFW window.
    static GLFWwindow* GetWindow();

    // Clean up resources and shutdown GLFW.
    static void Shutdown();

    // Offscreen render function that uses the provided camera parameters.
    // It renders the scene (e.g., a spinning cube with red lighting) offscreen
    // and returns its color attachment as an ImTextureID.
    static ImTextureID RenderScene(const glm::mat4 &view, const glm::mat4 &projection, const glm::vec3 &viewPos);

    // Resizes the offscreen framebuffer to the given dimensions.
    static void ResizeFramebuffer(int width, int height);

    // Retrieves the final rendered texture.
    static ImTextureID GetFinalRenderingTexture();

private:
    // Offscreen framebuffer and its attachments.
    static GLuint framebuffer;
    static GLuint colorTexture;
    static GLuint depthRenderbuffer;

    // Geometry for a simple cube.
    static GLuint cubeVAO;
    static GLuint cubeVBO;

    // Shader program used for rendering the scene.
    static GLuint shaderProgram;

    // Rotation angle for the spinning cube.
    static float rotationAngle;

    // Current offscreen framebuffer dimensions.
    static int fbWidth;
    static int fbHeight;

    // Helper function to compile and link shaders.
    static GLuint CompileShader(const char* vertexSrc, const char* fragmentSrc);

    // Sets up cube geometry and shader (called during initialization).
    static bool SetupScene();
};

#endif // ENGINE_H