[Docs] (README): Introduce this project.

README.md

@@ -1,12 +1,77 @@
 # MobileGL
 
-> [!NOTE]
-> **Important Note**: The project is undergoing a complete redesign and rewrite. The previous implementations have been removed or replaced.
+MobileGL is a *free (libre)* and *open-source* project that implements a desktop **OpenGL** API. The goal is to provide a complete OpenGL implementation with a state management layer and multiple backends.
+
+> **Status:** In development. Parts of the codebase are incomplete. Current short-term target: **OpenGL 3.3 Core Profile**.
+
+## Project positioning
+
+MobileGL is a ground-up implementation of a desktop OpenGL library. It aims to provide:
+
+* Full OpenGL state management.
+* A front-end that exposes OpenGL functions.
+* Pluggable backends so the same front-end and state machine can run on different graphics backends.
+
+This project is intended as an implementation/translation layer; it is not a driver nor a GPU firmware replacement currently.
+
+## Key components
+
+The repository is organized into a small number of top-level modules:
+
+1. **MG_State** — the OpenGL state machine and related state-management code.
+2. **MG_Impl** — the front-end OpenGL function implementations that mainly use `MG_State` and `MG_Backend`.
+3. **MG_Backend** — backend implementations that perform actual rendering. Example backend: `Direct (OpenGL ES)` backend.
+4. **MG_Util** and other utility modules.
 
 ## Third-party components
 
-**SPIRV-Cross** by **KhronosGroup** - [Apache License 2.0](https://github.com/KhronosGroup/SPIRV-Cross/blob/master/LICENSE): [github](https://github.com/KhronosGroup/SPIRV-Cross)
+MobileGL reuses several established open-source projects:
 
-**glslang** by **KhronosGroup** - [Various Licenses](https://github.com/KhronosGroup/glslang/blob/main/LICENSE.txt): [github](https://github.com/KhronosGroup/glslang)
+* **SPIRV-Cross** by **KhronosGroup** - [Apache License 2.0](https://github.com/KhronosGroup/SPIRV-Cross/blob/master/LICENSE): [github](https://github.com/KhronosGroup/SPIRV-Cross)
+* **glslang** by **KhronosGroup** - [Various Licenses](https://github.com/KhronosGroup/glslang/blob/main/LICENSE.txt): [github](https://github.com/KhronosGroup/glslang)
+* **DiligentCore** by **Diligent Graphics** - [Apache License 2.0](https://github.com/DiligentGraphics/DiligentCore/blob/master/License.txt): [github](https://github.com/DiligentGraphics/DiligentCore)
 
-**DiligentCore** by **Diligent Graphics** - [Apache License 2.0](https://github.com/DiligentGraphics/DiligentCore/blob/master/License.txt): [github](https://github.com/DiligentGraphics/DiligentCore)
+Refer to each component's repository for exact license texts. Any bundled third-party code in this repository is included under the upstream project's license.
+
+## Compatibility & target
+
+* **Short-term target:** Implement `OpenGL 3.3 (Core Profile)`.
+* **Current development focus:** MG_State and MG_Impl for `OpenGL 3.3 (Core Profile)`, and a `Direct (OpenGL ES)` backend implementation. These components are incomplete.
+
+## Build Instructions
+
+We currently provide **no releases** and **no precompiled binaries**.  
+If you want to try the project right now, you’ll need to build it yourself:
+
+1. Clone the repository:
+
+   ```sh
+   git clone https://github.com/your/project.git
+   ```
+
+2. Initialize and update all submodules recursively:
+
+   ```sh
+   git submodule update --init --recursive
+   ```
+
+3. Follow glslang’s own documentation for its required initiation.
+
+4. Configure and build the project with CMake:
+
+   ```sh
+   cmake -B build
+   cmake --build build
+   ```
+   
+   Alternatively, you can use platform-specific build commands as needed.
+
+## Notice
+
+* MobileGL is **not** production-ready currently.
+* Many features required by a full OpenGL 3.3 implementation are still missing or incomplete.
+* Performance optimizatins are now almost missing.
+
+## License
+
+This project is distributed under **GNU LGPL v2.1**. See the `LICENSE` file in the repository for the full text.