Layer System

/**
 * Abstract base class for all deck.gl layers
 * Provides attribute management, lifecycle methods, and rendering infrastructure
 */
abstract class Layer<PropsT = {}> {
  /** Initialize layer with properties */
  constructor(props: LayerProps<PropsT>);
  
  /** Abstract method to initialize layer state - must be implemented by subclasses */
  abstract initializeState(context: LayerContext): void;
  
  /** Update layer state when props or data changes */
  updateState(params: UpdateParameters<Layer>): void;
  
  /** Clean up layer resources */
  finalizeState(context: LayerContext): void;
  
  /** Render the layer to WebGL context */
  draw(opts: DrawLayerParameters): void;
  
  /** Handle picking interactions and return picking info */
  getPickingInfo(params: GetPickingInfoParams): PickingInfo;
  
  /** Transform world coordinates to screen space */
  project(xyz: [number, number, number]): [number, number, number];
  
  /** Transform screen coordinates to world space */
  unproject(xy: [number, number]): [number, number, number];
  
  /** Update layer state (partial update) */
  setState(partialState: any): void;
  
  /** Mark layer as needing redraw */
  setNeedsRedraw(): void;
  
  /** Get number of data instances */
  getNumInstances(): number;
  
  /** Get attribute manager for this layer */
  getAttributeManager(): AttributeManager;
  
  /** Check if layer state needs update */
  needsUpdate(): boolean;
  
  /** Check if layer needs redraw */
  needsRedraw(opts?: {clearRedrawFlags?: boolean}): boolean;
  
  /** Get shader uniforms for this layer */
  getShaders(): any;
  
  /** Get loading options for data fetching */
  getLoadOptions(): any;
  
  /** Layer unique identifier */
  readonly id: string;
  
  /** Current layer properties */
  readonly props: LayerProps<PropsT>;
  
  /** Layer rendering context */
  readonly context: LayerContext;
  
  /** Internal layer state */
  readonly state: any;
  
  /** Whether this is a composite layer */
  readonly isComposite: boolean;
  
  /** Whether this layer renders directly to GPU */
  readonly isDrawable: boolean;
}

interface LayerProps<PropsT = {}> {
  /** Unique layer identifier */
  id: string;
  
  /** Layer data - array or data source */
  data?: LayerData;
  
  /** Whether layer is visible */
  visible?: boolean;
  
  /** Layer opacity (0-1) */
  opacity?: number;
  
  /** Whether layer objects can be picked */
  pickable?: boolean;
  
  /** Coordinate system for layer data */
  coordinateSystem?: CoordinateSystem;
  
  /** Origin for coordinate system */
  coordinateOrigin?: [number, number, number];
  
  /** Model matrix for transforming layer */
  modelMatrix?: number[];
  
  /** Position accessor function or constant */
  getPosition?: Accessor<PropsT, Position>;
  
  /** Layer extensions to apply */
  extensions?: LayerExtension[];
  
  /** Hover event handler */
  onHover?: (info: PickingInfo, event: MjolnirEvent) => boolean | void;
  
  /** Click event handler */
  onClick?: (info: PickingInfo, event: MjolnirEvent) => boolean | void;
  
  /** Data loading callback */
  onDataLoad?: (data: any) => void;
  
  /** Error handling callback */
  onError?: (error: Error) => void;
  
  /** Data transform function */
  dataTransform?: (data: any) => any;
  
  /** Data comparison function for change detection */
  dataComparator?: (newData: any, oldData: any) => boolean;
  
  /** Custom data fetching function */
  fetch?: (url: string, opts: any) => Promise<any>;
  
  /** Loaders for data parsing */
  loaders?: any[];
  
  /** Load options for data fetching */
  loadOptions?: any;
  
  /** Auto-highlighting configuration */
  autoHighlight?: boolean;
  
  /** Highlighted object index */
  highlightedObjectIndex?: number;
  
  /** Highlight color */
  highlightColor?: Color;
  
  /** Update triggers for attribute invalidation */
  updateTriggers?: {[key: string]: any};
  
  /** Animation parameters */
  transitions?: {[key: string]: any};
  
  /** Material properties for 3D rendering */
  material?: Material;
  
  /** Rendering operation type */
  operation?: string;
}

interface UpdateParameters<LayerT extends Layer = Layer> {
  /** Layer being updated */
  layer: LayerT;
  
  /** Previous props */
  oldProps: LayerT['props'];
  
  /** Current props */
  props: LayerT['props'];
  
  /** Context for rendering */
  context: LayerContext;
  
  /** Flags indicating what changed */
  changeFlags: ChangeFlags;
  
  /** Previous layer state */
  oldState: any;
  
  /** Current layer state */
  state: any;
}

interface ChangeFlags {
  /** Data changed */
  dataChanged: boolean;
  
  /** Props changed */
  propsChanged: boolean;
  
  /** View or projection changed */
  viewportChanged: boolean;
  
  /** Update triggers changed */
  updateTriggersChanged: boolean;
  
  /** Extensions changed */
  extensionsChanged: boolean;
  
  /** Anything changed */
  somethingChanged: boolean;
}

import { Layer, COORDINATE_SYSTEM } from "@deck.gl/core";

// Define a custom layer
class MyCustomLayer extends Layer {
  static layerName = 'MyCustomLayer';
  
  initializeState(context) {
    // Initialize WebGL resources
    const {device} = context;
    
    this.state = {
      model: this._createModel(device)
    };
    
    // Set up attribute manager
    const attributeManager = this.getAttributeManager();
    attributeManager.addInstanced({
      instancePositions: {
        size: 3,
        accessor: 'getPosition'
      },
      instanceColors: {
        size: 4,
        type: 'uint8',
        normalized: true,
        accessor: 'getColor',
        defaultValue: [255, 0, 0, 255]
      }
    });
  }
  
  updateState({props, oldProps, changeFlags}) {
    // Handle prop changes
    if (changeFlags.dataChanged) {
      this.state.numInstances = props.data?.length || 0;
    }
  }
  
  draw({uniforms}) {
    const {model} = this.state;
    model.draw(this.context.renderPass, {
      uniforms: {
        ...uniforms,
        opacity: this.props.opacity
      }
    });
  }
  
  getPickingInfo({info, mode}) {
    // Customize picking info
    if (info.object) {
      info.customData = this.props.data[info.index];
    }
    return info;
  }
  
  _createModel(device) {
    // Create WebGL model
    // Implementation details...
  }
}

// Use the custom layer
const layer = new MyCustomLayer({
  id: 'my-layer',
  data: myDataArray,
  getPosition: d => d.coordinates,
  getColor: d => d.color || [255, 0, 0, 255],
  pickable: true,
  coordinateSystem: COORDINATE_SYSTEM.LNGLAT
});

/**
 * Abstract base class for composite layers
 * Enables layer composition by rendering sublayers instead of direct GPU rendering
 */
abstract class CompositeLayer<PropsT = {}> extends Layer<PropsT> {
  /** Abstract method to define sublayers - must be implemented by subclasses  */
  abstract renderLayers(): Layer[] | Layer;
  
  /** Get currently rendered sublayers */
  getSubLayers(): Layer[];
  
  /** Filter sublayers during rendering */
  filterSubLayer(context: FilterContext): boolean;
  
  /** Generate properties for sublayers */
  getSubLayerProps(props: any): any;
  
  /** Get sublayer constructor class */
  getSubLayerClass(id: string, DefaultClass: any): any;
  
  /** Whether this is a composite layer (always true) */
  readonly isComposite: true;
  
  /** Whether this layer renders directly (always false) */
  readonly isDrawable: false;
}

interface FilterContext {
  /** Current layer being filtered */
  layer: Layer;
  
  /** Viewport being rendered */
  viewport: Viewport;
  
  /** Render pass type */
  renderPass: string;
  
  /** Whether layer is selected for rendering */
  isPicking: boolean;
}

import { CompositeLayer, ScatterplotLayer, LineLayer } from "@deck.gl/core";

// Define a composite layer
class MultiDataLayer extends CompositeLayer {
  static layerName = 'MultiDataLayer';
  
  renderLayers() {
    const {data, pointRadius, lineWidth} = this.props;
    
    return [
      // Render points
      new ScatterplotLayer(
        this.getSubLayerProps({
          id: 'points',
          data: data.points,
          getPosition: d => d.coordinates,
          getRadius: pointRadius,
          getFillColor: [255, 0, 0]
        })
      ),
      
      // Render lines
      new LineLayer(
        this.getSubLayerProps({
          id: 'lines', 
          data: data.lines,
          getSourcePosition: d => d.start,
          getTargetPosition: d => d.end,
          getWidth: lineWidth,
          getColor: [0, 255, 0]
        })
      )
    ];
  }
}

// Use the composite layer
const compositeLayer = new MultiDataLayer({
  id: 'multi-data',
  data: {
    points: pointsData,
    lines: linesData
  },
  pointRadius: 100,
  lineWidth: 5
});

/**
 * Abstract base class for layer extensions
 * Provides composable functionality that can be applied to any layer
 */
abstract class LayerExtension {
  constructor(opts?: any);
  
  /** Add/modify shader code */
  getShaders(extension: this): any;
  
  /** Initialize extension state */
  initializeState(context: LayerContext, extension: this): void;
  
  /** Update extension state */
  updateState(params: UpdateParameters<Layer>, extension: this): void;
  
  /** Modify drawing behavior */
  draw(params: any, extension: this): void;
  
  /** Extension identifier */
  static extensionName: string;
}

// Using extensions with layers
const layerWithExtensions = new ScatterplotLayer({
  id: 'points-with-extensions',
  data: myData,
  getPosition: d => d.coordinates,
  getRadius: 100,
  extensions: [
    new DataFilterExtension({filterSize: 2}),
    new BrushingExtension()
  ]
});

// Data types
type LayerData<T = any> = T[] | LayerDataSource<T>;

interface LayerDataSource<T> {
  length: number;
  [key: number]: T;
}

// Accessor types
type Accessor<ObjectT, ValueT> = ValueT | AccessorFunction<ObjectT, ValueT>;

type AccessorFunction<ObjectT, ValueT> = 
  (object: ObjectT, context: AccessorContext<ObjectT>) => ValueT;

interface AccessorContext<ObjectT> {
  /** Index of current object */
  index: number;
  
  /** Complete data array */
  data: LayerData<ObjectT>;
  
  /** Target array being populated */
  target: any[];
}

// Common value types
type Position = [number, number] | [number, number, number];
type Color = [number, number, number] | [number, number, number, number];

// Material properties
interface Material {
  /** Ambient reflection factor */
  ambient?: number;
  
  /** Diffuse reflection factor */
  diffuse?: number;
  
  /** Shininess for specular reflection */
  shininess?: number;
  
  /** Specular reflection color */
  specularColor?: [number, number, number];
}

interface LayerState {
  /** Layer initialization complete */
  initialized: boolean;
  
  /** Attribute manager instance */
  attributeManager: AttributeManager;
  
  /** WebGL models for rendering */
  models?: any[];
  
  /** Number of data instances */
  numInstances?: number;
  
  /** Custom layer state */
  [key: string]: any;
}

interface DrawLayerParameters {
  /** Shader uniforms */
  uniforms: any;
  
  /** Render pass parameters */
  parameters?: any;
  
  /** Module settings */
  moduleSettings?: any;
  
  /** Context for rendering */
  context: LayerContext;
}

// Advanced layer with state management
class AdvancedLayer extends Layer {
  initializeState(context) {
    this.setState({
      models: [],
      uniformBuffer: null,
      instanceCount: 0
    });
    
    // Initialize attribute manager
    const attributeManager = this.getAttributeManager();
    attributeManager.addInstanced({
      positions: {size: 3, accessor: 'getPosition'},
      colors: {size: 4, accessor: 'getColor'},
      sizes: {size: 1, accessor: 'getSize'}
    });
  }
  
  updateState({props, oldProps, changeFlags}) {
    super.updateState({props, oldProps, changeFlags});
    
    if (changeFlags.dataChanged) {
      this.setState({
        instanceCount: props.data?.length || 0
      });
    }
    
    if (changeFlags.propsChanged) {
      this.getAttributeManager().invalidateAll();
    }
  }
  
  draw({uniforms}) {
    const {models} = this.state;
    const layerUniforms = {
      ...uniforms,
      instanceCount: this.state.instanceCount
    };
    
    for (const model of models) {
      model.draw(this.context.renderPass, {
        uniforms: layerUniforms
      });
    }
  }
}