# RegionFunction parametric or piecewise definition

Hi I want to plot a contourplot of a given surface over an specific region only. I have used the RegionFunction option for it. Now the problem is that the regions I need to plot are defined by parametric curves and or piecewise functions depending on the case. Which I don't know how to implement in combination with RegionFunction. Here a mere example of what I've done

Show[ContourPlot[V[x, y] + GG[x, y], {x, 0, 2}, {y, 0, 2},
MaxRecursion -> 2,
RegionFunction -> Function[{x, y, z}, x - 1 < 0.36397 y],
GridLines -> Automatic],
ParametricPlot[{(s - 0.28 Sin[2 Pi*s/Sqrt[4*2]])/
Sqrt, (s + 0.28 Sin[2 Pi*s/Sqrt[4*2]])/Sqrt}, {s, 0,
2 Sqrt}]
] And what I really want to achieve is something like this gimp manipulated plot. where the plot region is defined by everything above my parametric curve

• can you provide V and GG? – kglr Jul 30 '18 at 23:48
• maybe using ParametricPlot[{(s - 0.28 Sin[2 Pi*s/Sqrt[4*2]])/Sqrt, v (s + 0.28 Sin[2 Pi*s/Sqrt[4*2]])/Sqrt}, {s, 0, 2 Sqrt}, {v, 0, 1}, PlotStyle -> Opacity[1, White], Mesh -> None]? – kglr Jul 30 '18 at 23:56
• the exact V and GG are really long to include in the question, both can be any z=f(x,y) function let us say Sin[2Pi(x-y)]. The idea is to cut the surface along the parametric curve in blue. So although your comment works to imitate the desire result in ContourPlot[] may not be generalized to let's say Plot3D[] – Jared Lo Jul 31 '18 at 1:29