[Feat] (...): Add FramebufferState while implementing these gl functions.

MG/MG_GL/State/Framebuffer/FramebufferState.h

@@ -0,0 +1,48 @@
+//
+// Created by BZLZHH on 2025/5/3.
+//
+
+#ifndef MOBILEGL_FRAMEBUFFERSTATE_H
+#define MOBILEGL_FRAMEBUFFERSTATE_H
+#define MOBILEGL_GLSTATE_H
+
+#include "../../../Includes.h"
+
+struct FramebufferAttachment {
+    GLenum type = GL_NONE;
+    GLuint handle = 0;
+    GLint mipLevel = 0;
+    GLint zoffset = 0;
+};
+
+struct FramebufferObject {
+    bool generated = false;
+    std::unordered_map<GLenum, FramebufferAttachment> attachments;
+    GLenum status = GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT;
+    GLsizei width = 0;
+    GLsizei height = 0;
+};
+
+class FramebufferState {
+public:
+    // Return: the validity of the operation
+    GLenum Create(GLuint* framebuffer);
+    GLenum CreateN(GLsizei n, GLuint* framebuffers);
+    GLenum Delete(GLuint framebuffer);
+    GLenum Bind(GLenum target, GLuint framebuffer);
+    GLenum glAttachTexture2D(GLenum target, GLenum attachment,
+                             GLenum textarget, GLuint texture, GLint level);
+    GLenum glValidateCompleteness(GLenum target);
+    FramebufferObject* GetCurrentFBO(GLenum target);
+    
+private:
+    std::unordered_map<GLuint, FramebufferObject> framebuffers_;
+    std::unordered_map<GLenum, GLuint> currentBindings_; // READ/DRAW/FRAMEBUFFER
+    std::set<GLuint> freeIds_;
+    GLuint lastId_ = 0;
+    bool ValidateHandle(GLuint framebuffer);
+    static void UpdateCompleteness(FramebufferObject& fbo);
+    static bool ValidateAttachmentCombination(const FramebufferObject& fbo);
+};
+
+#endif //MOBILEGL_FRAMEBUFFERSTATE_H