Leaflet#43 Patch to fix intensity/altitude issue (auto max)

This patch works by automatically setting the max as it changes on each zoom level as points get combined/separated.

You no longer need to manually set options.max

When calculating the max value it considers all points (even if they are off the screen). This way you always get the same results at a particular zoom level.

Thanks to @spacemansteve for pointing me in the right direction
ca1f430

src/HeatLayer.js

@@ -104,9 +104,6 @@ L.HeatLayer = (L.Layer ? L.Layer : L.Class).extend({
  if (this.options.gradient) {
  this._heat.gradient(this.options.gradient);
  }
- if (this.options.max) {
- this._heat.max(this.options.max);
- }
  },
 
  _reset: function () {
@@ -135,52 +132,54 @@ L.HeatLayer = (L.Layer ? L.Layer : L.Class).extend({
  bounds = new L.Bounds(
  L.point([-r, -r]),
  size.add([r, r])),
-
- max = this.options.max === undefined ? 1 : this.options.max,
- maxZoom = this.options.maxZoom === undefined ? this._map.getMaxZoom() : this.options.maxZoom,
- v = 1 / Math.pow(2, Math.max(0, Math.min(maxZoom - this._map.getZoom(), 12))),
  cellSize = r / 2,
  grid = [],
  panePos = this._map._getMapPanePos(),
  offsetX = panePos.x % cellSize,
  offsetY = panePos.y % cellSize,
- i, len, p, cell, x, y, j, len2, k;
+ i, len, p, cell, x, y, j, len2;
+
+ this._max = 1;
 
  // console.time('process');
  for (i = 0, len = this._latlngs.length; i < len; i++) {
  p = this._map.latLngToContainerPoint(this._latlngs[i]);
- if (bounds.contains(p)) {
- x = Math.floor((p.x - offsetX) / cellSize) + 2;
- y = Math.floor((p.y - offsetY) / cellSize) + 2;
-
- var alt =
- this._latlngs[i].alt !== undefined ? this._latlngs[i].alt :
- this._latlngs[i][2] !== undefined ? +this._latlngs[i][2] : 1;
- k = alt * v;
-
- grid[y] = grid[y] || [];
- cell = grid[y][x];
-
- if (!cell) {
- grid[y][x] = [p.x, p.y, k];
+ x = Math.floor((p.x - offsetX) / cellSize) + 2;
+ y = Math.floor((p.y - offsetY) / cellSize) + 2;
+
+ var alt =
+ this._latlngs[i].alt !== undefined ? this._latlngs[i].alt :
+ this._latlngs[i][2] !== undefined ? +this._latlngs[i][2] : 1;
+
+ grid[y] = grid[y] || [];
+ cell = grid[y][x];
+
+ if (!cell) {
+ cell = grid[y][x] = [p.x, p.y, alt];
+ cell.p = p;
+ } else {
+ cell[0] = (cell[0] * cell[2] + p.x * alt) / (cell[2] + alt); // x
+ cell[1] = (cell[1] * cell[2] + p.y * alt) / (cell[2] + alt); // y
+ cell[2] += alt; // cumulated intensity value
+ }
 
- } else {
- cell[0] = (cell[0] * cell[2] + p.x * k) / (cell[2] + k); // x
- cell[1] = (cell[1] * cell[2] + p.y * k) / (cell[2] + k); // y
- cell[2] += k; // cumulated intensity value
- }
+ // Set the max for the current zoom level
+ if (cell[2] > this._max) {
+ this._max = cell[2];
  }
  }
 
+ this._heat.max(this._max);
+
  for (i = 0, len = grid.length; i < len; i++) {
  if (grid[i]) {
  for (j = 0, len2 = grid[i].length; j < len2; j++) {
  cell = grid[i][j];
- if (cell) {
+ if (cell && bounds.contains(cell.p)) {
  data.push([
  Math.round(cell[0]),
  Math.round(cell[1]),
- Math.min(cell[2], max)
+ Math.min(cell[2], this._max)
  ]);
  }
  }