how can i get the lift and drag coefficient by reading the non dimensional plot3d files in techplot(cfd analyzer?

I don't know waht you mean that " the non dimensional plot3d files"!! I know that in plot3d file there are only the conserved variables(rho,rho*u,rho*v,rho*w,rho*e) We can specify a equation to get the Pressure or CP use these virable! but the grid informations are in aother plot3d file,i don't know how to intigrate Pressure or cp to get the lift coefficient!! about drag coefficient,we still need to know the fricton stress ,maybe you are in a wrong way just through plot3d file to get these coefficients!