parse line width function and call tile destructor from main thread

2 files changed, 49 insertions, 3 deletions

diff --git a/src/style/properties.cpp b/src/style/properties.cpp
index 0ea3fbfeef..499f0c7276 100644
--- a/src/style/properties.cpp
+++ b/src/style/properties.cpp
@@ -2,6 +2,7 @@
 
 
 #include <cassert>
+#include <cmath>
 
 using namespace llmr;
 
@@ -22,4 +23,48 @@ float functions::constant(float z, const std::vector<float>& values) {
 bool functions::constant(float z, const std::vector<bool>& values) {
     assert(values.size() == 1);
     return values.front();
-}
\ No newline at end of file
+}
+
+
+float functions::stops(float z, const std::vector<float>& stops) {
+    // We need an even number of stop values.
+    if (stops.size() % 2 != 0) return 0;
+
+    // Accounts for us rendering tiles at 512x512, so our zoom levels are shifted by 1.
+    z += 1;
+
+    bool smaller = false;
+    float smaller_z, smaller_val;
+    bool larger = false;
+    float larger_z, larger_val;
+
+    for (uint32_t i = 0; i < stops.size(); i += 2) {
+        float stop_z = stops[i];
+        float stop_val = stops[i + 1];
+        if (stop_z <= z && (!smaller || smaller_z < stop_z)) { smaller = true; smaller_z = stop_z; smaller_val = stop_val; }
+        if (stop_z >= z && (!larger || larger_z > stop_z)) { larger = true; larger_z = stop_z; larger_val = stop_val; }
+    }
+
+    if (smaller && larger) {
+        // Exponential interpolation between the values
+        if (larger_z == smaller_z) return smaller_val;
+        float val = smaller_val * pow(larger_val / smaller_val, (z - smaller_z) / (larger_z - smaller_z));
+        return val;
+    } else if (larger || smaller) {
+        // Do not draw a line.
+        return -std::numeric_limits<float>::infinity();
+
+        // Exponential extrapolation of the smaller or larger value
+        //var edge = larger || smaller;
+        //return Math.pow(2, z) * (edge.val / Math.pow(2, edge.z));
+    } else {
+        // No stop defined.
+        return 1;
+    }
+}
+
+bool functions::stops(float z, const std::vector<bool>& values) {
+    // TODO
+    return false;
+}
+
diff --git a/src/style/style.cpp b/src/style/style.cpp
index 9d476aba0a..3b95fb8792 100644
--- a/src/style/style.cpp
+++ b/src/style/style.cpp
@@ -173,6 +173,7 @@ template <typename T> FunctionProperty<T> Style::parseProperty(pbf data) {
             switch((Property)data.varint()) {
                 case Property::Null: property.function = &functions::null; break;
                 case Property::Constant: property.function = &functions::constant; break;
+                case Property::Stops: property.function = &functions::stops; break;
                 default: property.function = &functions::null; break;
             }
         } else if (data.tag == 2) { // value
@@ -222,11 +223,11 @@ void Style::cascade(float z) {
             const std::string& layer_name = line_pair.first;
             const llmr::LineClass& layer = line_pair.second;
 
-            // TODO: This should be restricted to fill styles that have actual
+            // TODO: This should be restricted to line styles that have actual
             // values so as to not override with default values.
             llmr::LineProperties& stroke = computed.lines[layer_name];
             stroke.hidden = layer.hidden(z);
-            stroke.width = 2; //layer.width(z);
+            stroke.width = layer.width(z);
             stroke.offset = layer.offset(z);
             stroke.color = layer.color;
             stroke.opacity = layer.opacity(z);