1 files changed, 60 insertions, 0 deletions
diff --git a/facetracknoir/lerp.hpp b/facetracknoir/lerp.hpp
new file mode 100644
index 00000000..0123832a
--- /dev/null
+++ b/facetracknoir/lerp.hpp
@@ -0,0 +1,60 @@
+#pragma once
+
+#include "facetracknoir/timer.hpp"
+#include <algorithm>
+#include <cmath>
+
+class lerp {
+private:
+    static const constexpr double eps = 1e-2;
+    double last[2][6], cam[6], dt;
+    Timer t;
+public:
+    lerp() :
+        last { {0,0,0,0,0,0}, {0,0,0,0,0,0} }, cam {0,0,0,0,0,0}, dt(1)
+    {
+    }
+    bool idempotentp(const double* input)
+    {
+        for (int i = 0; i < 6; i++)
+        {
+            double diff = fabs(cam[i] - input[i]);
+            if (diff > eps)
+                return false;
+        }
+        return true;
+    }
+
+    void write(const double* cam_, const double* input, double* output)
+    {
+        const double q = t.elapsed();
+        const double d = q/dt;
+
+        bool idem = idempotentp(cam_);
+
+        if (!idem)
+        {
+            dt = q;
+            t.start();
+        }
+
+        const double c = std::max(std::min(1.0, d), 0.0);
+
+        if (!idem)
+            for (int i = 0; i < 6; i++)
+            {
+                last[1][i] = last[0][i];
+                last[0][i] = input[i];
+                cam[i] = cam_[i];
+            }
+
+        for (int i = 0; i < 6; i++)
+            output[i] = last[1][i] + (last[0][i] - last[1][i]) * c;
+    }
+
+    void get_state(double* state)
+    {
+        for (int i = 0; i < 6; i++)
+            state[i] = last[0][i];
+    }
+};