🔮 abstracting tile handling, preparing usage of spatial indexing

main.js

@@ -12,10 +12,12 @@ require('coffee-script/register');
 
 const fs = require('fs');
 const Termap = require(__dirname+'/src/Termap');
+const Tile = require(__dirname+'/src/Tile')
 
 termap = new Termap();
 
 // TODO: abstracing this class, create loader class
 data = fs.readFileSync(__dirname+"/tiles/regensburg.pbf.gz");
-termap.renderer.features = termap.renderer._getFeatures(termap.renderer._parseTile(data));
+tile = new Tile(data);
+termap.renderer.features = tile.layers
 termap._draw();

src/Renderer.coffee

@@ -5,9 +5,6 @@
   The Console Vector Tile renderer - bäm!
 ###
 x256 = require 'x256'
-Protobuf = require 'pbf'
-VectorTile = require('vector-tile').VectorTile
-zlib = require 'zlib'
 triangulator = new (require('pnltri')).Triangulator()
 
 Canvas = require './Canvas'
@@ -66,29 +63,6 @@ module.exports = class Renderer
   setSize: (@width, @height) ->
     @canvas = new Canvas @width, @height
 
-  _parseTile: (buffer) ->
-    # extract, decode and parse a given tile buffer
-    new VectorTile new Protobuf zlib.gunzipSync buffer
-
-  _getFeatures: (tile) ->
-    features = {}
-    for name,layer of tile.layers
-      continue unless @config.layers[name]
-
-      features[name] = for i in [0...layer.length]
-        feature = layer.feature i
-        type = [undefined, "Point", "LineString", "Polygon"][feature.type]
-
-        properties = feature.properties
-        properties.$type = type
-
-        id: feature.id
-        type: type
-        properties: properties
-        points: feature.loadGeometry()
-
-    features
-
   draw: (@view, @zoom) ->
     return if @isDrawing
     @isDrawing = true
@@ -118,51 +92,34 @@ module.exports = class Renderer
     process.stdout.write output
 
   _drawLayers: ->
-    drawn = []
     for layer in @config.drawOrder
+      continue unless @features?[layer]
+
       @notify "rendering #{layer}..."
       scale = Math.pow 2, @zoom
-      continue unless @features?[layer]
 
       if @config.layers[layer].minZoom and @zoom > @config.layers[layer].minZoom
         continue
 
-      @canvas.strokeStyle = @canvas.fillStyle = @config.layers[layer].color
+      for feature in @features[layer].tree.search(minX: 0, minY: 0, maxX: 4096, maxY: 4096)
-
+        @_drawFeature layer, feature.data, scale
-      for feature in @features[layer]
-        if @_drawFeature layer, feature, scale
-          drawn.push feature
-
-    drawn
 
   _drawFeature: (layer, feature, scale) ->
     # TODO: this is ugly :) need to be fixed @style
     #return false if feature.properties.class is "ferry"
     feature.type = "LineString" if layer is "building" or layer is "road"
 
-    toDraw = []
+    # TODO: zoom level
-    for idx, points of feature.points
-      visible = false
-
-      projectedPoints = for point in points
-        projectedPoint =
-          x: point.x/scale
-          y: point.y/scale
-
-        visible = true if not visible and @_isOnScreen projectedPoint
-        projectedPoint
-
-      if idx is 0 and not visible
-        return false
-
-      continue unless visible
-      toDraw.push projectedPoints
-
     unless style = @styler.getStyleFor layer, feature, 14
       return false
 
     color = style.paint['line-color'] or style.paint['fill-color'] or style.paint['text-color']
 
+    toDraw = for points in feature.points
+      for point in points
+        x: point.x/scale
+        y: point.y/scale
+
     # TODO: zoom calculation todo for perfect styling
     if color instanceof Object
       color = color.stops[0][1]

src/Styler.coffee

@@ -39,10 +39,7 @@ module.exports = class Styler
     false
 
   _compileFilter: (filter) ->
-    if not filter or not filter.length
+    switch filter?[0]
-      return -> true
-
-    switch filter[0]
       when "all"
         filters = (@_compileFilter subFilter for subFilter in filter[1..])
         (feature) ->
@@ -64,3 +61,6 @@ module.exports = class Styler
         (feature) ->
           return false for value in filter[2..] when feature.properties[filter[1]] is value
           true
+
+      else
+        -> true

src/Tile.coffee

@@ -0,0 +1,67 @@
+###
+  termap - Terminal Map Viewer
+  by Michael Strassburger <codepoet@cpan.org>
+
+  Handling of and access to single VectorTiles
+###
+
+VectorTile = require('vector-tile').VectorTile
+Protobuf = require 'pbf'
+zlib = require 'zlib'
+Rbush = require('rbush')
+
+module.exports = class Tile
+  tree: null
+  layers: {}
+
+  constructor: (buffer, @styler = null) ->
+    @tree = new Rbush()
+    @tile = @_loadTile buffer
+
+    @_loadFeatures()
+
+  _loadTile: (buffer) ->
+    buffer = zlib.gunzipSync buffer if @_isGzipped buffer
+    new VectorTile new Protobuf buffer
+
+  _isGzipped: (buffer) ->
+    buffer.slice(0,2).indexOf(Buffer.from([0x1f, 0x8b])) is 0
+
+  _loadFeatures: ->
+    for name, layer of @tile.layers
+      tree = new Rbush()
+      features = for i in [0...layer.length]
+        # TODO: caching of similar attributes to avoid looking up the style each time
+        continue if @styler and not @styler.getStyleFor layer, feature
+
+        feature = layer.feature i
+
+        type = feature.properties.$type =
+          [undefined, "Point", "LineString", "Polygon"][feature.type]
+
+        data =
+          points: feature.loadGeometry()
+          properties: feature.properties
+          id: feature.id
+          type: type
+
+        @_addToTree tree, data
+        data
+
+      @layers[name] = tree: tree, features: features
+
+  _addToTree: (tree, data) ->
+    [minX, maxX, minY, maxY] = [Infinity, -Infinity, Infinity, -Infinity]
+    for outer in data.points
+      for p in outer
+        minX = p.x if p.x < minX
+        maxX = p.x if p.x > maxX
+        minY = p.y if p.y < minY
+        maxY = p.y if p.y > maxY
+
+    tree.insert
+      minX: minX
+      maxX: maxX
+      minY: minY
+      maxY: maxY
+      data: data