# Cat Engine Components
This document provides a comprehensive inventory of all built-in components in cat-engine.
## Transforms & Scene Graph
- **TransformComponent**
- Stores local TRS (translation, rotation, scale) and recomputes `matrix_world` for the scene graph.
- **TransformParentComponent**
- Allows overriding or managing parent-child transform relationships.
- **TransformPipelineComponent**
- Advanced transform derivation system supporting `Fork`, `Merge`, `SampleAncestor`, and `Drop`.
- **TransformPipelineMapComponent**
- Mapping functions for rotation, scale, and translation within a pipeline.
- **TransformTemporalFilterComponent**
- Smoothing filters for position and rotation (e.g., `QuatTemporalFilter`, `Vector3TemporalFilter`).
## Rendering
- **RenderableComponent**
- Links a mesh and material for 3D/2D rendering.
- **MeshComponent**
- Stores CPU-side geometry data before GPU upload.
- **ColorComponent**
- Per-instance RGBA tint multiplier.
- **OpacityComponent**
- Per-instance opacity. Determines if an object uses opaque or transparent render passes.
- **UVComponent**
- Supplies UV coordinates and tiling/offset data for shaders.
- **TextureComponent**
- Loads and caches textures by URI.
- **GLTFComponent**
- Loads glTF 2.0 models and spawns appropriate child hierarchies.
- **SkinnedMeshComponent**
- Enables skeletal animation by linking meshes to bones.
- **BackgroundComponent** / **BackgroundColorComponent**
- specialized rendering for environment backgrounds or solid clear colors.
- **BloomComponent** / **BlurPassComponent**
- Post-processing effects for glow and blurring.
- **EmissiveComponent**
- Configures emissive/glow properties for materials.
- **TransparentCutoutComponent**
- Enables alpha-testing (cutout) for transparent textures like foliage.
- **StencilClipComponent**
- Provides stencil-based masking for UI or portals.
## Lighting
- **PointLightComponent**
- Omnidirectional light source with range and intensity.
- **DirectionalLightComponent**
- Infinite parallel light source (e.g., sun).
- **AmbientLightComponent**
- Base global illumination color.
- **LightQuantizationComponent**
- Controls toon-shading steps for cel-shaded visuals.
## Input & Control
- **InputComponent**
- Primary sink for keyboard and mouse events.
- **InputTransformModeComponent**
- Maps input events to movement/rotation (e.g., FPS controls, WASD).
- **PointerComponent**
- Represents a mouse cursor or virtual pointer in 3D space.
- **TextInputComponent**
- Handles text entry, cursor position, and selection in text fields.
- **GestureCoordTypeComponent**
- Defines how drag interactions map to coordinates (WorldPlane, ScreenSpace, etc.).
## Camera
- **Camera2DComponent**
- Orthographic camera for 2D UI and games.
- **Camera3DComponent**
- Perspective camera for 3D environments.
- **CameraXRComponent**
- Stereoscopic camera used in VR/AR contexts.
## XR (Extended Reality)
- **OpenXRComponent**
- Integrates the OpenXR lifecycle into the engine.
- **InputXRComponent** / **ControllerXRComponent**
- Manages VR controller poses, buttons, and haptics.
## Physics & Collision
- **CollisionComponent**
- Marks a transform as a physical body (STATIC, KINEMATIC, RIGGED).
- **CollisionShapeComponent**
- Defines the primitive or mesh-based shape used for collision detection.
- **KineticResponseComponent**
- Automatically resolves overlaps by pushing the body out of collisions.
- **GravityComponent**
- Defines a local gravity field that affects children in its subtree.
- **BoundsComponent** / **LayoutBoundsComponent**
- Tracks axis-aligned bounding boxes for rendering or layout logic.
- **FitBoundsComponent**
- Dynamically scales or positions a subtree to fit within specified bounds.
## UI & Layout
- **LayoutComponent**
- Implements a flexbox-like layout system for nesting and alignment.
- **StyleComponent**
- Stores CSS-like visual properties (margins, padding, display, justify).
- **TextComponent**
- Renders dynamic text strings with support for fonts and alignment.
- **HtmlElementComponent**
- Maps semantic HTML tags (e.g., `div`, `span`) to engine behaviors.
- **ScrollingComponent**
- Enables scrollable regions with clipping and inertia.
- **OverlayComponent**
- Forces a subtree to render on top of the main scene.
## Audio
- **AudioClipComponent**
- References and plays audio files.
- **AudioOutputComponent** / **AudioMixComponent**
- Nodes in the audio graph for output and sub-mixing.
- **AudioOscillatorComponent**
- Generates synthesized waveforms (Sine, Square, Saw).
- **MusicContextComponent** / **MusicNoteComponent**
- High-level musical orchestration (tempo, scales, note triggers).
- **AudioFilterComponents**
- Real-time filters: `LowPass`, `HighPass`, `BandPass`, `Gain`, `Limiter`.
## Signals & Logic
- **ActionComponent**
- Encapsulates discrete executable actions or script triggers.
- **RouterComponent** / **SignalObserverRouterComponent**
- Manages event propagation and scoped signal handling.
- **DataComponent**
- General-purpose key-value storage (numbers, strings, booleans).
- **ClockComponent**
- Provides a centralized time source for animations and periodic events.
- **SerializeComponent**
- Flags whether a component subtree should be saved/loaded.
- **ComponentRef**
- A utility component that holds a reference to another `ComponentId`.
## Animation
- **AnimationComponent**
- Animates properties over time using curves or keyframes.
- **KeyframeComponent**
- Stores a sequence of timed values for complex animations.
- **IKChainComponent**
- Implements Inverse Kinematics for procedural limb posing.
## Editor & Tools
- **EditorComponent**
- General marker for components used exclusively by the editor.
- **GizmoComponent**
- Visual handles for translating, rotating, and scaling objects.
- **SelectionComponent** / **SelectableComponent**
- Manages the visual and logical state of selected objects.
- **GridComponent**
- Renders a reference grid in the 3D viewport.
## Scripts (Planned)
- **MeowMeowComponent**
- A planned component to encapsulate state and logic defined entirely within `.mms` scripts.
