don't treat negative values as placement failure

include/llmr/text/types.hpp

@@ -99,7 +99,12 @@ struct PlacementProperty {
     explicit PlacementProperty(float zoom, const PlacementRange &rotationRange)
         : zoom(zoom), rotationRange(rotationRange) {}
 
-    float zoom = -1.0f;
+    inline operator bool() const {
+        return !isnan(zoom) && zoom != std::numeric_limits<float>::infinity() &&
+               rotationRange[0] != rotationRange[1];
+    }
+
+    float zoom = std::numeric_limits<float>::infinity();
     PlacementRange rotationRange = {{0.0f, 0.0f}};
 };
 

src/text/placement.cpp

@@ -305,10 +305,9 @@ void Placement::addFeature(TextBucket& bucket,
         PlacementProperty place =
             collision.place(glyphs, anchor, anchor.scale, maxPlacementScale,
                             padding, horizontal);
-
-        if (place.zoom >= 0.0f) {
+        if (place) {
             bucket.addGlyphs(glyphs, place.zoom, place.rotationRange,
-                               zoom - zOffset);
+                             zoom - zOffset);
         }
     }
 }