I have this:
f[x_, y_] := x^2/(x^2 + y^2)
Plot3D[f[x, y], {x, -3, 3}, {y, -3, 3},
PlotStyle -> Opacity[.8],
MeshFunctions -> {#3 &}, PlotPoints -> 100,
AxesLabel -> {x, y},
Ticks -> {Range[-3, 3], Range[-3, 3]},
FaceGrids -> {{{0, 0, -1}, {Range[-3, 3], Range[-3, 3]}}}]
Which gives the following image:

Now, I want to add a 2D contour plot on the xy-plane below the surface of f. Does anyone have a suggestion?
cplot3d = Graphics3D[Cases[cplot, GraphicsComplex[pts_, rest__] :> GraphicsComplex[Append[#, level] & /@ pts, rest]]]wherecplotis theContourPlotandlevelis chosen/calculated appropriately. Combine withplot3dwithShow[plot3d, cplot3d, PlotRange -> All].... – Michael E2 Dec 15 '14 at 11:36cplot3d = Plot3D[level, {x, -1.2, 1.2}, {y, -1.2, 1.2}, MeshFunctions -> {f[#1, #2] &}]. You'll need to set explicit numbers forMeshin both plots to get the contours to match (e.g.Mesh -> {Range[0,1,0.1]}). Also related: 7772. – Michael E2 Dec 15 '14 at 11:43