add 'heights-interpolation', 'biomes-interpolation'

src/maths/Heightmap.cpp

@@ -5,6 +5,17 @@
 #include <stdexcept>
 #include <glm/glm.hpp>
 
+std::optional<InterpolationType> InterpolationType_from(std::string_view str) {
+    if (str == "nearest") {
+        return InterpolationType::NEAREST;
+    } else if (str == "linear") {
+        return InterpolationType::LINEAR;
+    } else if (str == "cubic") {
+        return InterpolationType::CUBIC;
+    }
+    return std::nullopt;
+}
+
 static inline float sample_at(
     const float* buffer,
     uint width,