MPE_Draw_logic
Sets logical operation for laying down new pixels 
Synopsis
#include "mpe.h" 
int MPE_Draw_logic( graph, function )
MPE_XGraph graph;
int function;
Input Parameters
- graph 
- MPE graphics handle
- function 
- integer specifying one of the following:
'MPE_LOGIC_COPY' - no logic, just copy the pixel
'MPE_LOGIC_XOR'  - xor the new pixel with the existing one
and many more... see 'mpe_graphics.h'
Notes For Fortran Interface 
The Fortran interface to this routine is different from its C
counterpart and it has an additional argument, ierr, at the end
of the argument list, i.e. the returned function value (the error
code) in C interface is returned as the additional argument in
Fortran interface.  The Fortran interface is invoked with the
CALL statement.
All MPI and MPE objects, MPI_Comm, MPE_XGraph and MPE_Color, are
of type INTEGER in Fortran.
Location:../src/graphics/src/mpe_graphics.c