I'm having problems implementing the tesselation routine call inside
a mesh block, and it seems to be related to the UV-coordinates.
  Examining the UV code I noticed something strange (perhaps a bug?).

  At the beginning of Parse_Mesh() three UV-vectors are created:

  UV_VECT UV1, UV2, UV3;

  They are not initialized anywhere. The next time they are used is when
reading a triangle:

        Parse_Three_UVCoords(UV1,UV2,UV3);
        Triangles[number_of_triangles].UV1 = Mesh_Hash_UV(&number_of_uvcoords,
&max_uvcoords, &UVCoords,UV1);
        Triangles[number_of_triangles].UV2 = Mesh_Hash_UV(&number_of_uvcoords,
&max_uvcoords, &UVCoords,UV2);
        Triangles[number_of_triangles].UV3 = Mesh_Hash_UV(&number_of_uvcoords,
&max_uvcoords, &UVCoords,UV3);

  This means, as I understand it, that it reads three UV coordinates from
the input and then adds them to the current triangle.

  Examining Parse_Three_UVCoords function we see that the vectors are not
initialized if there are no UV-coordinates in that triangle:

int Parse_Three_UVCoords(UV_VECT UV1, UV_VECT UV2, UV_VECT UV3)
{
  int Return_Value;

  EXPECT
    CASE(UV_VECTORS_TOKEN)
#ifdef UnofficialBlocking
      parseUnofficialFeature(30);
#endif
      Parse_UV_Vect(UV1);  Parse_Comma();
      Parse_UV_Vect(UV2);  Parse_Comma();
      Parse_UV_Vect(UV3);

      Return_Value = 1;
      EXIT
    END_CASE

    OTHERWISE
      Return_Value = 0;
      UNGET
      EXIT
    END_CASE

  END_EXPECT

  return(Return_Value);
}

  This would mean that if there are no uv-coordinates in a triangle, the
previous value (either an unassigned value, which is most probably random,
or the value of a previous uv-definition) is used.
  Somehow I don't think this is what was intended. Specially using
unassigned values as uv-coordinates. It would also mean that the coloring
of non-uv triangles will depend on the declaration order with respect to
uv-triangles in the same mesh.

-- 
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););}    /*- Warp -*/

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>       Parse_UV_Vect(UV1);  Parse_Comma();
>       Parse_UV_Vect(UV2);  Parse_Comma();
>       Parse_UV_Vect(UV3);

	It seems that Parse_UV_Vect in express.c first assign zero
for the 5 coordinates of the vector.


*** Nicolas Calimet
*** http://pov4grasp.free.fr

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Nicolas Calimet wrote:
> 
> >       Parse_UV_Vect(UV1);  Parse_Comma();
> >       Parse_UV_Vect(UV2);  Parse_Comma();
> >       Parse_UV_Vect(UV3);
> 
>         It seems that Parse_UV_Vect in express.c first assign zero
> for the 5 coordinates of the vector.

	...But this is done only if CASE(UV_VECTORS_TOKEN) is actually
reached when parsing the mesh, so it might be true that initialisation
is missing somewhere...

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"Warp" <war### [at] tagpovrayorg> wrote...
>
>         Parse_Three_UVCoords(UV1,UV2,UV3);
>         Triangles[number_of_triangles].UV1 =
Mesh_Hash_UV(&number_of_uvcoords, &max_uvcoords, &UVCoords,UV1);
>         Triangles[number_of_triangles].UV2 =
Mesh_Hash_UV(&number_of_uvcoords, &max_uvcoords, &UVCoords,UV2);
>         Triangles[number_of_triangles].UV3 =
Mesh_Hash_UV(&number_of_uvcoords, &max_uvcoords, &UVCoords,UV3);

I think there should be an "if" in there to check the value that is returned
from Parse_Three_UVCoords (it returns zero if nothing is parsed).  Either
that or the vectors should be initialized to zero before they are parsed.

-Nathan

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