// @(#)root/gl:$Id: TGLSphere.cxx 21453 2007-12-18 15:18:30Z matevz $
// Author:  Timur Pocheptsov  03/08/2004
// NOTE: This code moved from obsoleted TGLSceneObject.h / .cxx - see these
// attic files for previous CVS history

/*************************************************************************
 * Copyright (C) 1995-2006, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
#include "TGLSphere.h"
#include "TGLRnrCtx.h"
#include "TGLQuadric.h"
#include "TGLIncludes.h"

#include "TBuffer3D.h"
#include "TBuffer3DTypes.h"

// For debug tracing
#include "TClass.h"
#include "TError.h"

//______________________________________________________________________________
//
// Implements a native ROOT-GL sphere that can be rendered at
// different levels of detail.

ClassImp(TGLSphere)

//______________________________________________________________________________
TGLSphere::TGLSphere(const TBuffer3DSphere &buffer) :
   TGLLogicalShape(buffer)
{
   // Default ctor
   fRadius = buffer.fRadiusOuter;

   // TODO:
   // Support hollow & cut spheres
   // buffer.fRadiusInner;
   // buffer.fThetaMin;
   // buffer.fThetaMax;
   // buffer.fPhiMin;
   // buffer.fPhiMax;
}

//______________________________________________________________________________
UInt_t TGLSphere::DLOffset(Short_t lod) const
{
   // Return display-list offset for given LOD.
   // Calculation based on what is done in virtual QuantizeShapeLOD below.

   UInt_t  off = 0;
   if      (lod >= 100) off = 0;
   else if (lod <  10)  off = lod / 2;
   else                 off = lod / 10 + 4;
   return off;
}

//______________________________________________________________________________
Short_t TGLSphere::QuantizeShapeLOD(Short_t shapeLOD, Short_t combiLOD) const
{
   // Factor in scene/viewer LOD and quantize.

   Int_t lod = ((Int_t)shapeLOD * (Int_t)combiLOD) / 100;

   if (lod >= 100)
   {
      lod = 100;
   }
   else if (lod > 10)
   {  // Round LOD above 10 to nearest 10
      Double_t quant = 0.1 * ((static_cast<Double_t>(lod)) + 0.5);
      lod            = 10  *   static_cast<Int_t>(quant);
   }
   else
   {  // Round LOD below 10 to nearest 2
      Double_t quant = 0.5 * ((static_cast<Double_t>(lod)) + 0.5);
      lod            = 2   *   static_cast<Int_t>(quant);
   }
   return static_cast<Short_t>(lod);
}

//______________________________________________________________________________
void TGLSphere::DirectDraw(TGLRnrCtx & rnrCtx) const
{
   // Debug tracing
   if (gDebug > 4) {
      Info("TGLSphere::DirectDraw", "this %d (class %s) LOD %d", this, IsA()->GetName(), rnrCtx.ShapeLOD());
   }

   // 4 stack/slice min for gluSphere to work
   UInt_t divisions = rnrCtx.ShapeLOD();
   if (divisions < 4) {
      divisions = 4;
   }
   gluSphere(rnrCtx.GetGluQuadric(), fRadius, divisions, divisions);
}