I'm still trying to convert a quad into a triangle. I got this code (it's being worked on, hence it looks so ugly):
[code=pascal]
{ .: DrawQuad :. }
procedure DrawQuad(X, Y, Wid, Hgt, Lev, Tu, Tu2, Tv, Tv2: Single);
var
V: array[0..3] of TBrainVector;
begin
Tv := 1 - Tv;
Tv2 := 1 - Tv2;

TexCoords.Add(TexCoord(Tu, Tv));
TexCoords.Add(TexCoord(Tu2, Tv));
TexCoords.Add(TexCoord(Tu2, Tv2));
TexCoords.Add(TexCoord(Tu, Tv2));
V[0] := Vec3(X, Y, -Lev);
V[1] := Vec3(X + Wid, Y, -Lev);
V[2] := Vec3(X + Wid, Y - Hgt, -Lev);
V[3] := Vec3(X, Y - Hgt, -Lev);

Vertices.Add(V[0]);
Vertices.Add(V[1]);
Vertices.Add(V[2]);

Vertices.Add(V[2]);
Vertices.Add(V[3]);
Vertices.Add(V[0]);
end;
[/code]
The quad is drawn correctly, but there's something wrong with its texture coordinates. Can you point me out, what's wrong?