4

Consider this example

Graphics3D[{EdgeForm[None], Opacity[0.5],
 Blue,  Cuboid[{0, 0, 0}, {1, 1, 1/3}],
 Green, Cuboid[{0, 0, 1/3}, {1, 1, 2/3}],
 Red,   Cuboid[{0, 0, 2/3}, {1, 1, 1}],
 Gray, Opacity[1], Sphere[{1/2, 1/2, #/3 - 1/6}, 0.1] & /@ {1, 2, 3}},
Boxed -> False]

enter image description here

For the green box, the edges and the surfaces in the back are also quite visible. For blue and red boxes the contrast is much smaller. How to improve it such a way that the edges would be visible from the difference in colour and also make the balls inside visible?

One possible way can be using an extra layer with slightly different opacity

Graphics3D[{EdgeForm[None], Opacity[0.5],
  Blue, Cuboid[{0, 0, 0}, {1, 1, 1/3}],
  Green, Cuboid[{0, 0, 1/3}, {1, 1, 2/3}],
  Red, Cuboid[{0, 0, 2/3}, {1, 1, 1}],
 Opacity[0.6],
  Blue, Polygon[{{0, 0, 0}, {1, 0, 0}, {1, 1, 0}, {0, 1, 0}}],
  Red, Polygon[{{0, 0, 2/3}, {0, 1, 2/3}, {0, 1, 1}, {0, 0, 1}}],
 Gray, Opacity[1], Sphere[{1/2, 1/2, #/3 - 1/6}, 0.1] & /@ {1, 2, 3}},
 Boxed -> False]

enter image description here

For a lot of boxes, it does not seem to be a good option.

Sumit
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    Why not just adjust the opacity of each layer "by eye"? (Create a Manipulate to help you along.) My general principle in cases such as yours is to set the opacity high (0.9) for objects that obscure no others, and incrementally lower for other layers, and low (0.2) for objects that are not obscured by others. You might try EdgeForm[Orange] too. – David G. Stork Feb 07 '18 at 17:13
  • Thanks, @DavidG.Stork. I have to keep Opacity<=0.5, because I have to put some sticks and balls inside the boxes. I prefer the edges free from lines - it looks better. The problem is only with few specific colours. I was wondering if it can be fixed by adjusting the Lighting and shadow. – Sumit Feb 07 '18 at 17:31
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    I urge you to put the sticks into your figure here, so we know the TRUE problem you're solving. – David G. Stork Feb 07 '18 at 18:21
  • @DavidG.Stork. I modified my question. The objective is to make both the surfaces of the boxes and the object inside visible. – Sumit Feb 08 '18 at 07:51
  • (1) The Lighting -> "Neutral" option in Graphics3D can help equalize variations in shading between different colours. (2) You could use something like FaceForm[Opacity[0.3], Opacity[0.7]] to make the front faces more transparent than the back ones. –  Feb 08 '18 at 09:17

1 Answers1

2

One (tedious) way is to define a box with different Opacity for different surfaces.

opqbox[{x1_, y1_, z1_}, {x2_, y2_, z2_}, {d_, u_, l_, r_, b_, f_}] := {EdgeForm[None],
           Opacity[b], Polygon[{{x1, y1, z1}, {x2, y1, z1}, {x2, y2, z1}, {x1, y2, z1}}],
           Opacity[u], Polygon[{{x1, y1, z2}, {x2, y1, z2}, {x2, y2, z2}, {x1, y2, z2}}],
           Opacity[r], Polygon[{{x1, y1, z1}, {x2, y1, z1}, {x2, y1, z2}, {x1, y1, z2}}],
           Opacity[l], Polygon[{{x1, y2, z1}, {x2, y2, z1}, {x2, y2, z2}, {x1, y2, z2}}],
           Opacity[o], Polygon[{{x1, y1, z1}, {x1, y2, z1}, {x1, y2, z2}, {x1, y1, z2}}],
           Opacity[f], Polygon[{{x2, y1, z1}, {x2, y2, z1}, {x2, y2, z2}, {x2, y1, z2}}]}


opc={0.5,0.15,0.35,0.20,0.25,0.25};
Graphics3D[{EdgeForm[None],Opacity[0.5],
            Blue,opqbox[{0,0,0},{1,1,1/3},opc],
            Green,opqbox[{0,0,1/3},{1,1,2/3},opc],
            Red,opqbox[{0,0,2/3},{1,1,1},opc],
          Gray,Opacity[1],Sphere[{1/2,1/2,#/3-1/6},0.1]&/@{1,2,3}},
Boxed->False]

enter image description here

d, u, l, r, b, f are the Opacity for down, up, left, right, back and front face.

enter image description here

This cube is made by the method suggested by Michael E2 in this answer.

Sumit
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