Manipulate[DensityPlot[((Sin[x Cos[θ]+y Sin[θ]])^2),{x,-5,5},{y,-5,5}],{θ,0,2 Pi}]

Manipulate[DensityPlot[Total[Table[((Sin[K x Cos[θ]+K y Sin[θ]])^2),{θ,0,2 Pi,2 Pi/NN}]],{x,-5,5},{y,-5,5},PlotPoints->20],{K,0.1,10},{NN,1,100}]

(* Przekrój *)
Manipulate[Plot[Total[Table[((Sin[K x Cos[θ]])^2),{θ,0,2 Pi,2 Pi/NN}]],{x,-5,5},PlotPoints->100, PlotRange-> All],{K,0.1,10},{NN,1,100,1}]