1 files changed, 104 insertions, 0 deletions
diff --git a/src/base/CubicSpline.cpp b/src/base/CubicSpline.cpp
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+++ b/src/base/CubicSpline.cpp
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+//
+//  libavg - Media Playback Engine. 
+//  Copyright (C) 2003-2014 Ulrich von Zadow
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2 of the License, or (at your option) any later version.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//  Lesser General Public License for more details.
+//
+//  You should have received a copy of the GNU Lesser General Public
+//  License along with this library; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+//  Current versions can be found at www.libavg.de
+//
+
+#include "CubicSpline.h"
+#include "Exception.h"
+#include "MathHelper.h"
+
+#include <iostream>
+
+using namespace std;
+
+namespace avg {
+
+CubicSpline::CubicSpline(const vector<float>& x, const vector<float>& y, bool bLoop)
+{
+    AVG_ASSERT(x.size() == y.size());
+    for (unsigned i=0; i<x.size(); ++i) {
+        m_Pts.push_back(glm::vec2(x[i], y[i]));
+    }
+    init();
+}
+
+CubicSpline::CubicSpline(const vector<glm::vec2>& pts, bool bLoop)
+    : m_Pts(pts)
+{
+    init();
+}
+
+CubicSpline::~CubicSpline()
+{
+}
+
+float CubicSpline::interpolate(float orig)
+{
+    int len = m_Pts.size();
+    int low = 0;
+    int high = len-1;
+    // Binary search.
+    while (high - low > 1) {
+        int avg = (high+low) / 2;
+        if (m_Pts[avg].x > orig) {
+            high = avg;
+        } else {
+            low = avg;
+        }
+    }
+    float h = m_Pts[high].x - m_Pts[low].x;
+    float a = (m_Pts[high].x-orig)/h;
+    float b = (orig-m_Pts[low].x)/h;
+    
+    float y = a*m_Pts[low].y + b*m_Pts[high].y 
+            + ((a*a*a-a)*m_Y2[low] + (b*b*b-b)*m_Y2[high])*(h*h)/6.f;
+    return y;
+}
+
+void CubicSpline::init()
+{
+    int len = m_Pts.size();
+    for (int i=1; i<len; ++i) {
+        if (m_Pts[i].x <= m_Pts[i-1].x) {
+            throw Exception(AVG_ERR_INVALID_ARGS,
+                    "CubicSplines must have increasing x coordinates.");
+        }
+    }
+    vector<float> u(len-1,0);
+    m_Y2.push_back(0.f);
+    u[0] = 0.f;
+    for (int i=1; i<len-1; ++i) {
+        float sig = (m_Pts[i].x-m_Pts[i-1].x) / (m_Pts[i+1].x-m_Pts[i-1].x);
+        float p = sig * m_Y2[i-1]+2.0f;
+        m_Y2.push_back((sig-1.0f)/p);
+        u[i] = (m_Pts[i+1].y-m_Pts[i].y) / (m_Pts[i+1].x-m_Pts[i].x) - 
+                (m_Pts[i].y - m_Pts[i-1].y) / (m_Pts[i].x-m_Pts[i-1].x);
+        u[i] = (6.f*u[i]/(m_Pts[i+1].x-m_Pts[i-1].x) - sig*u[i-1]) / p;
+    }
+    float qn = 0.f;
+    float un = 0.f;
+
+    m_Y2.push_back((un-qn*u[len-2]) / (qn*m_Y2[len-2]-1.0f));
+
+    for (int i=len-2; i>=0; i--) {
+        m_Y2[i] = m_Y2[i]*m_Y2[i+1]+u[i];
+    }
+}
+
+}