Clear[v, x, w, z]
v[x_] := 0.5 - HeavisidePi[x]
w[x_] := HeavisideTheta[-1/2 - x]
z[x_] := HeavisideTheta[-1/2 +  x]
Manipulate[Plot[{v[x], w[x], z[x]}, {x, -r, r}, PlotRange -> {-1, 2}], {r, 1.5, 3}]