D:/VL/BuildSystem/VL_DISTRO/Visualization_Library_SDK/src/vlGraphics/BezierSurface.cpp

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/*  Copyright (c) 2005-2010, Michele Bosi                                             */
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#include <vlGraphics/BezierSurface.hpp>

using namespace vl;

//-----------------------------------------------------------------------------
void BezierPatch::resize(int x, int y)
{
  if ( ((x-1)/3)*3+1 != x  || ((y-1)/3)*3+1 != y )
  {
    vl::Log::error("BezierPatch::resize(): illegal patch dimensions.\n");
    mControlPoints.clear();
    // in debug mode stop here
    VL_CHECK( ((x-1)/3)*3+1 == x )
    VL_CHECK( ((y-1)/3)*3+1 == y )
    return;
  }

  mX = x;
  mY = y;
  mControlPoints.resize(mX*mY);
}
//-----------------------------------------------------------------------------
void BezierSurface::updateBezierSurface(bool gen_tex_coords)
{
  int patch_count = 0;
  for(unsigned ipatch=0; ipatch<patches().size(); ++ipatch)
    patch_count += ((patches()[ipatch]->x()-1)/3)*((patches()[ipatch]->y()-1)/3);

  ref<ArrayFloat3> vert_array = dynamic_cast<ArrayFloat3*>(vertexArray());
  if (!vert_array)
  {
    vert_array = new ArrayFloat3;
    setVertexArray(vert_array.get());
  }
  vert_array->resize(detail()*detail()*patch_count);

  ref<ArrayFloat2> texc_array = dynamic_cast<ArrayFloat2*>(texCoordArray(0));
  if ( gen_tex_coords )
  {
    if (!texc_array)
    {
      texc_array = new ArrayFloat2;
      setTexCoordArray(0,texc_array.get());
    }
    texc_array->resize(detail()*detail()*patch_count);
  }

  ref<DrawElementsUInt> de = drawCalls()->size() == 1 ? dynamic_cast<DrawElementsUInt*>(drawCalls()->at(0)) : NULL;
  if (!de)
  {
    drawCalls()->clear();
    de = new DrawElementsUInt(PT_QUADS);
    drawCalls()->push_back(de.get());
  }
  de->indices()->resize((detail()-1)*(detail()-1)*4*patch_count);

  int ivert = 0;
  int iquad = 0;
  for(unsigned ipatch=0, patch_num=0; ipatch<patches().size(); ++ipatch)
  {
    const BezierPatch* p = patches()[ipatch].get();
    for(int ix=0; ix<p->x()-3; ix+=3)
    for(int iy=0; iy<p->y()-3; iy+=3)
    {
      for(unsigned y=0; y<detail(); ++y)
      {
        // A   B   C   D
        // ^   ^   ^   ^
        // +---+---+---+
        // |   |   |   |
        // +---+---+---+
        // |   |   |   |
        // +---+---+---+
        // |   |   |   |
        // +---+---+---+
        Real v  = (Real)y/(detail()-1);
        Real ty = 1.0f - v;
        Real ty1 = 1.0f - ty;
        Real k0 = ty*ty*ty;
        Real k1 = 3*ty*ty*ty1;
        Real k2 = 3*ty*ty1*ty1;
        Real k3 = ty1*ty1*ty1;
        vec3 A = p->at(ix+0,iy+0)*k0 + p->at(ix+0,iy+1)*k1 + p->at(ix+0,iy+2)*k2 + p->at(ix+0,iy+3)*k3;
        vec3 B = p->at(ix+1,iy+0)*k0 + p->at(ix+1,iy+1)*k1 + p->at(ix+1,iy+2)*k2 + p->at(ix+1,iy+3)*k3;
        vec3 C = p->at(ix+2,iy+0)*k0 + p->at(ix+2,iy+1)*k1 + p->at(ix+2,iy+2)*k2 + p->at(ix+2,iy+3)*k3;
        vec3 D = p->at(ix+3,iy+0)*k0 + p->at(ix+3,iy+1)*k1 + p->at(ix+3,iy+2)*k2 + p->at(ix+3,iy+3)*k3;
        for(unsigned x=0; x<detail(); ++x, ++ivert)
        {
          Real u  = (Real)x/(detail()-1);
          Real tx = 1.0f - u;
          Real tx1 = 1.0f - tx;
          vert_array->at(ivert) = (fvec3)(A*tx*tx*tx + B*3*tx*tx*tx1 + C*3*tx*tx1*tx1 + D*tx1*tx1*tx1);
          if(gen_tex_coords)
          {
            texc_array->at(ivert).x() = (float)u;
            texc_array->at(ivert).y() = (float)v;
          }
        }
      }

      int istart = detail()*detail()*patch_num;
      for(unsigned y=0; y<detail()-1; ++y)
      {
        for(unsigned x=0; x<detail()-1; ++x)
        {
          de->indices()->at(iquad++) = istart + y    *detail() + x;
          de->indices()->at(iquad++) = istart + y    *detail() + x+1;
          de->indices()->at(iquad++) = istart + (y+1)*detail() + x+1;
          de->indices()->at(iquad++) = istart + (y+1)*detail() + x;
        }
      }
      ++patch_num;
    }
  }
}
//-----------------------------------------------------------------------------