From 63dccc011aedaa97c5f8d18bb9039079f0104d79 Mon Sep 17 00:00:00 2001
From: cignoni <paolo.cignoni@isti.cnr.it>
Date: Tue, 22 May 2007 21:21:27 +0000
Subject: [PATCH] Moved here from shadevis

---
 vcg/math/gen_normal.h | 165 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)
 create mode 100644 vcg/math/gen_normal.h

diff --git a/vcg/math/gen_normal.h b/vcg/math/gen_normal.h
new file mode 100644
index 00000000..caa08d58
--- /dev/null
+++ b/vcg/math/gen_normal.h
@@ -0,0 +1,165 @@
+/****************************************************************************
+* VCGLib                                                            o o     *
+* Visual and Computer Graphics Library                            o     o   *
+*                                                                _   O  _   *
+* Copyright(C) 2004                                                \/)\/    *
+* Visual Computing Lab                                            /\/|      *
+* ISTI - Italian National Research Council                           |      *
+*                                                                    \      *
+* All rights reserved.                                                      *
+*                                                                           *
+* This program is free software; you can redistribute it and/or modify      *   
+* it under the terms of the GNU General Public License as published by      *
+* the Free Software Foundation; either version 2 of the License, or         *
+* (at your option) any later version.                                       *
+*                                                                           *
+* This program 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 General Public License (http://www.gnu.org/licenses/gpl.txt)          *
+* for more details.                                                         *
+*                                                                           *
+****************************************************************************/
+/****************************************************************************
+  History
+
+$Log: gen_normal.h,v $
+****************************************************************************/
+
+#ifndef __VCG_GEN_NORMAL
+#define __VCG_GEN_NORMAL
+
+namespace vcg {
+
+template <class ScalarType>
+class GenNormal 
+{
+public:
+typedef Point3<ScalarType> Point3x;
+
+static void  Random(int vn, std::vector<Point3<ScalarType > > &NN)
+{
+  NN.clear();
+  while(NN.size()<vn)
+  {
+    Point3x pp(((float)rand())/RAND_MAX,
+	       ((float)rand())/RAND_MAX,
+	       ((float)rand())/RAND_MAX);
+    pp=pp*2.0-Point3x(1,1,1);
+    if(pp.SquaredNorm()<1)
+    {
+      Normalize(pp);
+      NN.push_back(pp);
+    }
+  }
+}
+static void UniformCone(int vn, std::vector<Point3<ScalarType > > &NN, ScalarType AngleRad, Point3x dir=Point3x(0,1,0))
+{
+  std::vector<Point3<ScalarType > > NNT;
+  NN.clear();
+  // per prima cosa si calcola il volume della spherical cap di angolo AngleRad
+  ScalarType Height= 1.0 - cos(AngleRad); // height is measured from top...
+  // Surface is the one of the tangent cylinder
+  ScalarType CapArea = 2.0*M_PI*Height;
+  ScalarType Ratio = CapArea / (4.0*M_PI );
+
+  printf("----------AngleRad %f Angledeg %f ratio %f vn %i vn2 %i \n",AngleRad,math::ToDeg(AngleRad),Ratio,vn,int(vn/Ratio));
+  Uniform(vn/Ratio,NNT);
+  printf("asked %i got %i (expecting %i instead of %i)\n", int(vn/Ratio), NNT.size(), int(NNT.size()*Ratio), vn);
+  typename std::vector<Point3<ScalarType> >::iterator vi;
+  
+  ScalarType DotProd = cos(AngleRad);
+  for(vi=NNT.begin();vi!=NNT.end();++vi)
+  {
+    if(dir*(*vi) >= DotProd) NN.push_back(*vi);
+  }
+ }
+
+
+static void Uniform(int vn, std::vector<Point3<ScalarType > > &NN)
+{
+  OctaLevel pp;
+
+  int ll=10;
+  while(pow(4.0f,ll)+2>vn) ll--;
+
+  pp.Init(ll);
+  sort(pp.v.begin(),pp.v.end());
+  int newsize = unique(pp.v.begin(),pp.v.end())-pp.v.begin();
+  pp.v.resize(newsize);
+
+  NN=pp.v;
+  Perturb(NN);
+ }
+
+static void Perturb(std::vector<Point3<ScalarType > > &NN)
+{
+  float width=0.2f/sqrt(float(NN.size()));
+
+  typename std::vector<Point3<ScalarType> >::iterator vi;
+  for(vi=NN.begin(); vi!=NN.end();++vi) 
+  {
+    Point3x pp(((float)rand())/RAND_MAX,
+	       ((float)rand())/RAND_MAX,
+	       ((float)rand())/RAND_MAX);
+    pp=pp*2.0-Point3x(1,1,1);
+    pp*=width;
+    (*vi)+=pp;
+    (*vi).Normalize();
+  }
+
+}
+
+private :
+class OctaLevel
+  {
+  public:
+    std::vector<Point3x> v;
+    int level;
+    int sz;
+
+    Point3f &Val(int i, int j) {
+      assert(i>=0 && i<sz);
+      assert(j>=0 && j<sz);
+      return v[i+j*sz];
+    }
+
+    void Init(int lev)
+    {
+      sz=pow(2.0f,lev+1)+1;
+      v.resize(sz*sz);
+      if(lev==0)
+      {
+        Val(0,0)=Point3x( 0, 0,-1); Val(0,1)=Point3x( 0, 1, 0);  Val(0,2)=Point3x( 0, 0,-1);
+        
+        Val(1,0)=Point3x(-1, 0, 0); Val(1,1)=Point3x( 0, 0, 1);   Val(1,2)=Point3x( 1, 0, 0);
+
+        Val(2,0)=Point3x( 0, 0,-1); Val(2,1)=Point3x( 0,-1, 0);   Val(2,2)=Point3x( 0, 0,-1);
+      }
+      else
+      {
+        OctaLevel tmp;
+        tmp.Init(lev-1);
+        int i,j;
+        for(i=0;i<sz;++i)
+          for(j=0;j<sz;++j)
+          {
+            if((i%2)==0 && (j%2)==0) 
+              Val(i,j)=tmp.Val(i/2,j/2);
+            if((i%2)!=0 && (j%2)==0) 
+                Val(i,j)=(tmp.Val(i/2+0,j/2)+tmp.Val(i/2+1,j/2))/2.0;
+            if((i%2)==0 && (j%2)!=0) 
+                Val(i,j)=(tmp.Val(i/2,j/2+0)+tmp.Val(i/2,j/2+1))/2.0;
+            if((i%2)!=0 && (j%2)!=0) 
+                Val(i,j)=(tmp.Val(i/2+0,j/2+0)+tmp.Val(i/2+0,j/2+1)+tmp.Val(i/2+1,j/2+0)+tmp.Val(i/2+1,j/2+1))/4.0;
+          }
+	typename std::vector<Point3<ScalarType> >::iterator vi;
+        for(vi=v.begin(); vi!=v.end();++vi) 
+            (*vi).Normalize();
+  
+      }
+    }
+  };
+};
+}
+#endif