1 files changed, 8 insertions, 1 deletions
diff --git a/src/mbgl/util/interpolate.hpp b/src/mbgl/util/interpolate.hpp
index ef066377da..d463ffc056 100644
--- a/src/mbgl/util/interpolate.hpp
+++ b/src/mbgl/util/interpolate.hpp
@@ -1,15 +1,19 @@
 #pragma once
 
+#include <mbgl/util/color.hpp>
+#include <mbgl/util/range.hpp>
+
 #include <array>
 #include <vector>
 #include <string>
 #include <type_traits>
 #include <utility>
-#include <mbgl/util/color.hpp>
 
 namespace mbgl {
 namespace util {
 
+float interpolationFactor(float base, Range<float> range, float z);
+
 template <class T, class Enabled = void>
 struct Interpolator;
 
@@ -78,5 +82,8 @@ template <class T>
 struct Interpolator<std::vector<T>>
     : Uninterpolated {};
 
+template <class T>
+constexpr bool Interpolatable = !std::is_base_of<Uninterpolated, Interpolator<T>>::value;
+
 } // namespace util
 } // namespace mbgl