Architecture

Sigil is built on a modular architecture designed to separate the declarative UI (Compose) from the underlying data model and the rendering engine. This separation allows for flexibility across different platforms.

Module Structure

1. sigil-compose (The Frontend)

• Role: Provides the Jetpack Compose API (MateriaCanvas, Box, Sphere).
• Function: It builds and manages a tree of Nodes using Compose's Applier system. It does not perform rendering directly.
• Dependency: Depends on sigil-schema and sigil-summon.

2. sigil-schema (The Data Model)

• Role: Defines the platform-agnostic, serializable data structures for the scene graph.
• Key Classes: SigilNodeData, MeshData, LightData.
• Function: Acts as the "Contract" between the Compose layer and the Engine layer. This allows the scene to be serialized (e.g., to JSON) or transmitted over a network.

3. sigil-summon (The Engine)

• Role: The core logic responsible for interpreting the scene graph and rendering it.
• Function:
  • Summoning: Converts SigilNodeData into actual GPU resources (Meshes, Shaders).
  • Rendering: Manages the render loop (Vulkan/WebGPU/Metal).
  • Context: SigilSummonContext holds the state of the active engine.

The Render Loop

1. Composition: You write Compose code (Box, Sphere).
2. Reconciliation: Compose detects changes (e.g., color changed from Red to Blue).
3. Update: The sigil-compose nodes update their internal properties.
4. Sync: These property updates are pushed to the sigil-summon engine objects.
5. Draw: The engine renders the updated frame to the canvas.

Platform Support

• JVM (Desktop): Uses AWT/Swing Canvas with Vulkan backing.
• JS (Web): Uses HTML5 Canvas with WebGPU (or WebGL2 fallback).
• Android/iOS: (Planned) SurfaceView and Metal layers.