# Understanding FaceGrids

I'm having difficulties with FaceGrids. This should be pretty basic, but the documentation isn't helpfull with its fancy and mostly useless examples (again!)

I just want to add 2 lines on the middle of each of the 6 faces of the bounding box.

Here's a MWE showing 6 lines on two faces :

ParametricPlot3D[{t Cos[6 t], Sin[4 t], t}, {t, 0, 2 Pi},
PlotRange -> {{-1, 1}, {-1, 1}, {-1, 1}},
Boxed -> True,
BoxStyle -> Directive[GrayLevel[0.8]],
FaceGrids -> {{0, 0, 1}, {0, 0, -1}}, (* How to make sense of this ? *)
FaceGridsStyle -> Directive[LightGray, Dashed],
AxesOrigin -> {0, 0, 0},
Ticks -> True,
Lighting -> "Neutral",
SphericalRegion -> True,
Method -> {"RotationControl" -> "Globe"},
ImageSize -> {700, 700}
]


Six face lines is too much. I need only two lines, on the middle of each of the 6 faces of the cube.

I think I got it. Is there a simpler way of doing this ?

FaceGrids -> {
{{1, 0, 0}, {{0}, {0}}},
{{-1, 0, 0}, {{0}, {0}}},
{{0, 1, 0}, {{0}, {0}}},
{{0, -1, 0}, {{0}, {0}}},
{{0, 0, 1}, {{0}, {0}}},
{{0, 0, -1}, {{0}, {0}}}
}


Unless there's a simpler way of doing this (?), here's a nice alternative to the reference box :

ParametricPlot3D[{t Cos[6 t], Sin[4 t], t}, {t, 0, 2 Pi},
PlotRange -> {{-1, 1}, {-1, 1}, {-1, 1}}, Boxed -> True,
BoxStyle -> Directive[GrayLevel[1]],
FaceGrids -> {
{{1, 0, 0}, {{0}, {0}}},
{{-1, 0, 0}, {{0}, {0}}},
{{0, 1, 0}, {{0}, {0}}},
{{0, -1, 0}, {{0}, {0}}},
{{0, 0, 1}, {{0}, {0}}},
{{0, 0, -1}, {{0}, {0}}}
},
FaceGridsStyle -> Directive[Gray, Dotted],
AxesOrigin -> {0, 0, 0},
Ticks -> True,
SphericalRegion -> True,
Method -> {"RotationControl" -> "Globe"},
ImageSize -> {700, 700}
]


Preview :

• maybe, slightly shorter, fc = {#, {{0}, {0}}} & /@ Join[#, -#] &@IdentityMatrix[3]? – kglr Mar 27 '16 at 15:03
• This is hard to understand (to me). It's too kryptic ! – Cham Mar 27 '16 at 15:07