# Removing some of the box in a Plot3D

In the image below, I have indicated parts of the box feature, which I would like gone. Is it possible to remove some of the box in a Plot3D, and if so, how? My code for generating the image is shown below, and I would like to know how to change it to have the desired effect.

 expr = ((1 - p1) p1 (-128 ((1 - p1) p1)^(3/2) (-1 + p2)^2 p2^2 + (384 (-1 + p1)^3 p1^3)/Sqrt[1/(p2 - p2^2)] + 128 Sqrt[(1 - p1) p1] (-1 + p2)^3 p2^3 (-3 + 2 Sqrt[((-1 + p2) p2)/((-1 + p1) p1)]) + 128 Sqrt[1/(p1 - p1^2)] (3 (-1 + p1) p1 (-1 + p2)^3 p2^3 - (-1 + p2)^4 p2^4 + (2 ((1 - p2) p2)^(7/2))/Sqrt[1/(p1 - p1^2)] + ((-1 + p2)^4 p2^4)/(((-1 + p2) p2)/((-1 + p1) p1))^(3/2) + 3 (-1 + p1)^4 p1^4 Sqrt[((-1 + p2) p2)/((-1 + p1) p1)] - 6 (-1 + p1)^4 p1^4 (((-1 + p2) p2)/((-1 + p1) p1))^(3/2)) + 4 (1 - p1) p1 (-128 ((1 - p2) p2)^(5/2) - 96/(1/(p2 - p2^2))^(5/2)) + 256 (-1 + p1)^2 p1^2 (((1 - p2) p2)^(3/2) + 3/(1/(p2 - p2^2))^(3/2))))/(64 (p1 - p2)^2 ((1 - p2) p2)^(3/2) (-1 + p1 + p2)^2) // Simplify;

Plot3D[If[p1 == p2, -(-1 + p1) p1, expr], {p1, 0.5, 0.999}, {p2, 0.5, 0.999}, Exclusions -> None, PlotLegends -> Automatic, AxesLabel -> {Subscript[p, 1], Subscript[p, 2]}, PlotPoints -> 100, ColorFunction -> (If[#3 < 0, Lighter[RGBColor[0.368417, 0.506779, 0.709798], 0.00], White] &), ColorFunctionScaling -> False, ViewPoint -> {1.8797, -2.3832, 1.4956}, ImageSize -> {400, Automatic}] • See this link – Hubble07 Jan 12 at 9:13
• Please post minimal working examples with your questions. Your question is about the Frame / Box and to get an answer does not require the use of a complicated function and multiple options to the Plot3D – Bob Hanlon Jan 12 at 18:46

Using Scaled coordinates and AxisEdge, we can easily position all the necessary elements:

Graphics3D[
{
Line[
Scaled /@ {
{0, 0, 0},
{0, 1, 0},
{1, 1, 0}
}
]
},
Axes -> True,
AxesStyle -> Black,
AxesEdge -> {{-1, -1}, {1, -1}, {-1, -1}},
Boxed -> False
] Using AxesEdge -> …, we force the axes to be drawn on the proper sides of the plot. The missing two lines on the bottom are drawn using Line, with coordinates specified using Scaled.

I've omitted the plot itself to make it easier to see the relevant parts. You can simply combine this with the plot using Show:

Show[
Plot3D[
If[p1 == p2, -(-1 + p1) p1, expr],
{p1, 0.5, 0.999},
{p2, 0.5, 0.999},
Exclusions -> None,
PlotLegends -> Automatic,
AxesLabel -> {Style[Subscript[p, 1], Black, 18], Style[Subscript[p, 2], Black, 18], Style["expr", Black, 18]},
PlotPoints -> 100,
ColorFunction -> (If[#3 < 0, Lighter[RGBColor[0.368417, 0.506779, 0.709798], 0.00], White] &),
ColorFunctionScaling -> False,
ImageSize -> {400, Automatic},
Axes -> True,
AxesStyle -> Black,
AxesEdge -> {{-1, -1}, {1, -1}, {-1, -1}},
Boxed -> False
],
Graphics3D[
{
Line[
Scaled /@ {
{0, 0, 0},
{0, 1, 0},
{1, 1, 0}
}
]
}
]
] This solution is based on trial and error

Show[Plot3D[
If[p1 == p2, -(-1 + p1) p1, expr], {p1, 0.5, 0.999}, {p2, 0.5,
0.999}, Exclusions -> None, PlotLegends -> Automatic,
AxesLabel -> {Style[Subscript[p, 1], Black, 18],
Style[Subscript[p, 2], Black, 18], Style["expr", Black, 18]},
PlotPoints -> 100,
ColorFunction -> (If[#3 < 0,
Lighter[RGBColor[0.368417, 0.506779, 0.709798], 0.00],
White] &), ColorFunctionScaling -> False,
ViewPoint -> {1.8797, -2.3832, 1.4956},
ImageSize -> {400, Automatic}, Boxed -> False,
AxesStyle -> Directive[Black, Thick, 12]],
Graphics3D[{Thick, Black,
Line[{{0.49, 0.49, -0.13}, {0.49, 1.008, -0.13}, {1.008,
1.008, -0.13}}], ViewPoint -> {1.8797, -2.3832, 1.4956}}]] 