Added AGENTS.md documenting project structure, building, and running instructions.

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+# Project Overview
+
+Sixth 3D Demos is a collection of demo applications showcasing the Sixth 3D rendering engine. It features interactive 3D visualizations including Conway's Game of Life, galaxy simulations, and various geometric demos.
+
+## Build and Test Commands
+
+### Build the project
+```bash
+mvn clean package
+```
+
+### Compile only (without packaging)
+```bash
+mvn clean compile
+```
+
+### Run the application
+```bash
+java -jar target/sixth-3d-demos.jar
+```
+
+### Generate API documentation
+```bash
+mvn javadoc:javadoc
+```
+
+### Run a specific demo directly
+```bash
+# Run the launcher
+java -cp target/sixth-3d-demos.jar eu.svjatoslav.sixth.e3d.examples.launcher.Main
+
+# Run Game of Life demo
+java -cp target/sixth-3d-demos.jar eu.svjatoslav.sixth.e3d.examples.life_demo.Main
+
+# Run Point Cloud Galaxy demo
+java -cp target/sixth-3d-demos.jar eu.svjatoslav.sixth.e3d.examples.galaxy_demo.PointCloudDemo
+```
+
+### Testing
+This project currently has no automated tests. Testing is done manually by running the demo applications.
+
+## Code Organization
+
+```
+src/main/java/eu/svjatoslav/sixth/e3d/examples/
+├── launcher/           - Application launcher and GUI
+│   ├── Main.java       - Main entry point
+│   └── ApplicationListPanel.java
+├── life_demo/          - Conway's Game of Life 3D demo
+│   ├── Main.java
+│   ├── Cell.java
+│   ├── Matrix.java
+│   └── Star.java
+├── galaxy_demo/        - Galaxy simulation demo
+│   ├── Galaxy.java
+│   └── PointCloudDemo.java
+├── RandomPolygonsDemo.java
+├── OctreeDemo.java
+├── GraphDemo.java
+├── TextEditorDemo.java
+├── TextEditorDemo2.java
+├── RainingNumbersDemo.java
+└── package-info.java
+```
+
+## Code Style Guidelines
+
+### Java Version
+- Java 8 (source and target compatibility)
+
+### Indentation and Formatting
+- Use 4 spaces for indentation (no tabs)
+
+## External Dependencies
+
+| Dependency | Version | Description |
+|------------|---------|-------------|
+| sixth-3d | 1.3-SNAPSHOT | 3D rendering engine |
+| svjatoslavcommons | 1.8 | Utility library |
+
+Both are available from the svjatoslav.eu Maven repository.
+
+## Common Patterns in This Codebase
+
+### Creating a Demo Application
+1. Create a class with a `main` method
+2. Create a `ViewFrame` to display the 3D scene
+3. Get the `ShapeCollection` from the view panel
+4. Add shapes to the collection
+5. Optionally set up user input handling
+
+### Extending AbstractCompositeShape
+Use this pattern for creating composite 3D objects:
+```java
+public class MyShape extends AbstractCompositeShape {
+    public MyShape(Transform transform) {
+        super(transform);
+        // Add child shapes using addShape()
+    }
+}
+```
+
+### Handling User Input
+Implement `MouseInteractionController` for mouse events, or extend input tracker classes for keyboard input.
+