# Thick border on some ParametricPlot3D objects

Object x should be composed of thick lines, object su should have no or a thin border.

With BoundaryStyle, I am not able to differentiate between x and su. I haven't had much luck with PlotStyle -> {Thick, } or PlotStyle -> {EdgeForm[Thick], } either.

x1 := {u, 0, 0}
x2 := {u, 1, 1}
x3 := {0, w, w}
x4 := {1, w, w}
x := {x1, x2, x3, x4}
su := {u, (1 - u) w^2 + u w^2, (1 - u) w + u w}
ParametricPlot3D[{x, su}, {u, 0, 1}, {w, 0, 1}]


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Since your x's are just lines, why not just render them as separate primitives (i.e. with Line[]) and then combine them with your surface using Show[]? –  Ｊ. Ｍ. Apr 14 '13 at 13:31
To be precise, did you want something like this? –  Ｊ. Ｍ. Apr 14 '13 at 13:37
@J.M. Yes, exactly like this. However, x1-x4 do not necessarily have to be straight lines, they can also be functions that meet in the corners. –  Frank Apr 14 '13 at 13:39
In that case, you'll have to invoke ParametricPlot3D[] twice; once for your surface, and once for your curves, and then combine all that with Show[]. –  Ｊ. Ｍ. Apr 14 '13 at 13:41
The "lines" or edges of 3D plots are not controlled by PlotStyle (as one might think from 2D experience), but by BoundaryStyle. Since this is applied to all objects in the plot, I suggest plotting them one at a time and combining with Show:
ParametricPlot3D[#, {u, 0, 1}, {w, 0, 1}, BoundaryStyle -> #2, Mesh -> None] & @@@

It somehow seems perverse to me that BoundaryStyle affects curves, seeing that they don't really have a boundary... :) –  Ｊ. Ｍ. Apr 14 '13 at 13:57