dawarich/app/javascript/maps_maplibre/layers/heatmap_layer.js

import { BaseLayer } from './base_layer'

/**
 * Heatmap layer showing point density
 * Uses MapLibre's native heatmap for performance
 */
export class HeatmapLayer extends BaseLayer {
  constructor(map, options = {}) {
    super(map, { id: 'heatmap', ...options })
    this.opacity = options.opacity || 0.6
  }

  getSourceConfig() {
    return {
      type: 'geojson',
      data: this.data || {
        type: 'FeatureCollection',
        features: []
      }
    }
  }

  getLayerConfigs() {
    return [
      {
        id: this.id,
        type: 'heatmap',
        source: this.sourceId,
        paint: {
          // Fixed weight
          'heatmap-weight': 1,

          // low intensity to view major clusters
          'heatmap-intensity': [
            'interpolate',
            ['linear'],
            ['zoom'],
            0, 0.01,
            10, 0.1,
            15, 0.3
          ],

          // Color ramp
          'heatmap-color': [
            'interpolate',
            ['linear'],
            ['heatmap-density'],
            0, 'rgba(0,0,0,0)',
            0.4, 'rgba(0,0,0,0)',
            0.65, 'rgba(33,102,172,0.4)',
            0.7, 'rgb(103,169,207)',
            0.8, 'rgb(209,229,240)',
            0.9, 'rgb(253,219,199)',
            0.95, 'rgb(239,138,98)',
            1, 'rgb(178,24,43)'
          ],

          // Radius in pixels, exponential growth
          'heatmap-radius': [
            'interpolate',
            ['exponential', 2],
            ['zoom'],
            10, 5,
            15, 10,
            20, 160
          ],

          // Visible when zoomed in, fades when zoomed out
          'heatmap-opacity': [
            'interpolate',
            ['linear'],
            ['zoom'],
            0, 0.3,
            10, this.opacity,
            15, this.opacity
          ]
        }
      }
    ]
  }
}