Calculate clip IDs with a huffman prefix tree

This changes the clip IDs from sequential to a huffman prefix tree, meaning that
parent tiles share the same prefix with child tiles (but are shorter). This allows
us to use the same checkerboard pattern to draw all tiles.

TODO:
- make sure we're not overflowing the 8 bit limit of the stencil buffer
- draw all checkerboard fields at the same time, with one draw call
- fix raster drawing (fading, clipping)

refs #132

src/map/map.cpp

@@ -5,6 +5,9 @@
 #include <llmr/style/sprite.hpp>
 #include <llmr/util/transition.hpp>
 #include <llmr/util/time.hpp>
+#include <llmr/util/math.hpp>
+#include <llmr/util/clip_ids.hpp>
+#include <llmr/util/string.hpp>
 
 #include <algorithm>
 #include <memory>
@@ -138,7 +141,6 @@ void Map::setup() {
     sources.emplace("mapbox streets",
                     std::unique_ptr<Source>(new Source(*this,
                            painter,
-                           texturepool,
                            "http://a.gl-api-us-east-1.tilestream.net/v3/mapbox.mapbox-streets-v4/%d/%d/%d.gl.pbf",
                            Source::Type::vector,
                            {{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 }},
@@ -150,7 +152,6 @@ void Map::setup() {
     sources.emplace("satellite",
                     std::unique_ptr<Source>(new Source(*this,
                            painter,
-                           texturepool,
                            "https://a.tiles.mapbox.com/v3/justin.hh0gkdfm/%d/%d/%d%s.png256",
                            Source::Type::raster,
                            {{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 }},
@@ -331,7 +332,11 @@ void Map::toggleRaster() {
 
         if (satellite_source.enabled) {
             satellite_source.enabled = false;
-            style.appliedClasses.erase(style.appliedClasses.find("satellite"));
+
+            auto style_class = style.appliedClasses.find("satellite");
+            if (style_class != style.appliedClasses.end()) {
+                style.appliedClasses.erase(style_class);
+            }
         } else {
             satellite_source.enabled = true;
             style.appliedClasses.insert("satellite");
@@ -350,6 +355,28 @@ void Map::updateTiles() {
     }
 }
 
+
+
+void Map::updateClippingIDs() {
+    std::forward_list<Tile::ID> ids;
+
+    for (auto &pair : sources) {
+        const std::unique_ptr<Source> &source = pair.second;
+        if (source->enabled) {
+            ids.splice_after(ids.before_begin(), source->getIDs());
+        }
+    }
+
+    const std::map<Tile::ID, ClipID> clipIDs = computeClipIDs(ids);
+
+    for (auto &pair : sources) {
+        const std::unique_ptr<Source> &source = pair.second;
+        if (source->enabled) {
+            source->updateClipIDs(clipIDs);
+        }
+    }
+}
+
 void Map::prepare() {
     view.make_active();
 
@@ -366,14 +393,14 @@ void Map::prepare() {
         style.sprite->load(kSpriteURL);
     }
 
-    if (style.sprite && style.sprite->raster->isLoaded() && !style.sprite->raster->textured) {
-        style.sprite->raster->setTexturepool(&texturepool);
-    }
-
     updateTiles();
+
+    updateClippingIDs();
 }
 
 void Map::render() {
+    std::vector<std::string> debug;
+
     painter.clear();
 
     painter.resize();
@@ -386,26 +413,30 @@ void Map::render() {
 
     painter.prepareClippingMask();
 
-    bool is_baselayer = true;
-
+    size_t source_id = 0;
     for (auto &pair : sources) {
         Source &source = *pair.second;
-        source.prepare_render(state, is_baselayer);
-        is_baselayer = source.enabled ? false : (true && is_baselayer);
+        size_t count = source.prepareRender(state);
+        debug.emplace_back(util::sprintf<100>("source %d: %d\n", source_id, count));
+        source_id++;
     }
 
     painter.finishClippingMask();
 
+
     // Then, render each source's tiles. TODO: handle more than one
     // vector source.
 
     for (auto &pair : sources) {
         Source &source = *pair.second;
-        source.render(animationTime);
+        painter.setCurrentSourceName(pair.first);
+        source.render();
     }
 
     painter.renderMatte();
 
+    painter.renderDebugText(debug);
+
     // Schedule another rerender when we definitely need a next frame.
     if (transform.needsTransition()) {
         update();