PrimObj[origin_ , LatticeVecA_ ,  
        LatticeVecB_ ]  :=  {
Graphics[{RGBColor[1, 
              0,  .5], 
            Disk[origin, 0.3]}], 
Graphics[{RGBColor[ .5, 
              0, 1], Disk[origin  +  LatticeVecA, 
              0.3]}], 
Graphics[{RGBColor[1,  .5, 0], 
            Disk[origin  +  LatticeVecB, 
              0.3]}], 
Graphics[{RGBColor[ .5, 1, 0], 
            Disk[origin +  LatticeVecA +  LatticeVecB, 
              0.3]}]
}

Show[PrimObj[{-1/2, -1/2}, {0, 1}, {2, 1}], Axes -> True, 
      AspectRatio -> Automatic]