Also interpolate taxi and interactive objects

src/items/InteractiveObject.h

@@ -4,6 +4,7 @@
 #include <Eigen/Core>
 #include "render/Renderer.h"
 #include "InteractiveObjectState.h"
+#include <chrono>
 
 namespace FRG {
 
@@ -30,6 +31,8 @@ namespace FRG {
 
 		void draw(Renderer& renderer) const;
 		void drawDarklands(Renderer& renderer) const;
+		void drawShadowDepth(Renderer& renderer) const;
+		void capturePresentationState();
 		const std::string& entityId() const { return id; }
 
 	private:
@@ -38,6 +41,21 @@ namespace FRG {
 		friend class LocationEditor;
 		friend class ScriptEngine;
 		InteractiveObjectState& state; // non-owning binding to LocationGameState
+
+		struct PresentationSample {
+			Eigen::Vector3f position = Eigen::Vector3f::Zero();
+			float rotationY = 0.f;
+			float scale = 1.f;
+			float alpha = 1.f;
+			bool isActive = true;
+		};
+
+		PresentationSample previousPresentationSample_;
+		PresentationSample currentPresentationSample_;
+		std::chrono::steady_clock::time_point lastPresentationUpdate_;
+		bool hasPresentationSample_ = false;
+
+		PresentationSample interpolatedPresentationState() const;
 	};
 
 } // namespace FRG