// #including this include file afte #including shapes.inc (or stdinc.inc)
// will modify the HF macros so that they write Wavefront OBJ files instead of
// MESH2 files. Note that you can't place the height_fields in your scene at
// the same time, because POV-Ray can't understand the obj format.
// Also, with this modification, the HF macros always write the data to a file,
// so you must remember to specify a file name, for example "myobject.obj".

// Version 1.0 (may contain bugs)
// by Rune S. Johansen
// August 2002

#macro HFCreate_ ()
   
   #fopen _HFMACRO_OUTPUT_FILE FileName write
   #write(_HFMACRO_OUTPUT_FILE,"# vertex vectors\n",

   #local J = 1;
   #while (J<=xRes)
      #local K = 1;
      #while (K<=zRes)
         "v ",PArr[J][K].x," ",PArr[J][K].y," ",PArr[J][K].z,"\n",
         #declare K = K+1;
      #end
      #declare J = J+1;
   #end
   
   "\n")

   #if (Smooth)
      #write(_HFMACRO_OUTPUT_FILE,"# normal vectors\n",

      // CALCULATION OF NORMAL VECTOR
      // We don't vnormalize the vectors from the current center point
      // to its neightbor points because we want a weighted average
      // where bigger areas contribute more. This also means that the
      // center point can be left out completely of the calculations:
      #local J = 1;
      #while (J<=xRes)
         #local K = 1;
         #while (K<=zRes)
            #local Normal =
            vnormalize(vcross(
               PArr[J][K+1]-PArr[J][K-1],
               PArr[J+1][K]-PArr[J-1][K]
            ));
            "vn ",Normal.x," ",Normal.y," ",Normal.z,"\n",
            #declare K = K+1;
         #end
         #declare J = J+1;
      #end
      "\n")
   #end

   #if (UVtex)
      #write(_HFMACRO_OUTPUT_FILE,"# uv vectors\n",
      #local J = 1;
      #while (J<=xRes)
         #local K = 1;
         #while (K<=zRes)
            "vt ",(J-1)/(xRes-1)," ",(K-1)/(zRes-1),"\n",
            #declare K = K+1;
         #end
         #declare J = J+1;
      #end
      "\n")
   #end
   
   #write(_HFMACRO_OUTPUT_FILE,"# face indices\n",
   #local F1 = <0,zRes,zRes+1>;
   #local F2 = <0,zRes+1,1>;
   #local J = 0;
   #while (J<xRes-1)
      #local A = J*zRes;
      #while (mod(A+1,zRes))
         "f ",(F1+A).x+1," ",(F1+A).y+1," ",(F1+A).z+1,"\n",
         "f ",(F2+A).x+1," ",(F2+A).y+1," ",(F2+A).z+1,"\n",
         #local A = A+1;
      #end
      #local J = J+1;
   #end
   #if (UVtex)
      "\n")
      #fclose _HFMACRO_OUTPUT_FILE
   #else
      "\n")
      #fclose _HFMACRO_OUTPUT_FILE
   #end

#end