From ff9d900791810d4c9339a9c782da19316068263c Mon Sep 17 00:00:00 2001
From: Guillaume Bittoun <guillaume.bittoun@gmail.com>
Date: Wed, 5 Nov 2014 21:37:46 +0000
Subject: [PATCH] simplex_interpolator: adding interpolator skeleton

---
 src/lol/math/simplex_interpolator.h | 76 +++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 src/lol/math/simplex_interpolator.h

diff --git a/src/lol/math/simplex_interpolator.h b/src/lol/math/simplex_interpolator.h
new file mode 100644
index 00000000..9de4a358
--- /dev/null
+++ b/src/lol/math/simplex_interpolator.h
@@ -0,0 +1,76 @@
+//
+// Lol Engine
+//
+// Copyright: (c) 2010-2014 Sam Hocevar <sam@hocevar.net>
+//            (c) 2013-2014 Benjamin "Touky" Huet <huet.benjamin@gmail.com>
+//            (c) 2013-2014 Guillaume Bittoun <guillaume.bittoun@gmail.com>
+//   This program is free software; you can redistribute it and/or
+//   modify it under the terms of the Do What The Fuck You Want To
+//   Public License, Version 2, as published by Sam Hocevar. See
+//   http://www.wtfpl.net/ for more details.
+//
+
+#pragma once
+
+template<int N /* Dimension of the space */, typename T = float /* floating type used for interpolation */>
+class simplex_interpolator
+{
+public:
+
+    simplex_interpolator()
+    {
+        this->InitBase();
+    }
+
+    inline arraynd<N, T> & GetSamples()
+    {
+        return this->samples;
+    }
+
+    // Single interpolation
+    inline T interp(vec_t<T, N> position)
+    {
+        vec_t<T, N> simplex_position = this->ToSimplexRef(position);
+
+        // TODO
+
+        return 0;
+    }
+
+protected:
+
+    inline void InitBase()
+    {
+        base.SetSize(vec_t<int, 2>(N, N));
+        base_inverse.SetSize(vec_t<int, 2>(N, N));
+
+        for (int i = 0 ; i < N ; ++i)
+        {
+            for (int j = i ; j < N ; ++j)
+            {
+                base[i][j] = sqrt((i+2)/(2*i + 2)) / (j > i ? i + 2 : 1);
+                base_inverse[i][j] = sqrt((2*j + 2)/(j+2)) * (j > i ? (1 / (float)j) : 1);
+            }
+        }
+    }
+
+    inline vec_t<T, N> ToSimplexRef(vec_t<T, N> const & position)
+    {
+        vec_t<T, N> result;
+
+        for (int i = 0 ; i < N ; ++i)
+        {
+            for (int j = i ; j < N ; ++j)
+            {
+                result[i] += base_inverse[i][j] * position[j];
+            }
+        }
+
+        return result;
+    }
+
+    arraynd<2, T> base;
+    arraynd<2, T> base_inverse;
+
+    arraynd<N, T> samples;
+};