[Question]
  [
Write a program that reads a \$n\times n \times n\$ array of binary values which represent an \$n\times n \times n\$ cube, that consists of \$n^3\$ smaller cubes. Each value says whether there is a voxel (small cube) present in the given position or not. The program must output the given array as an ASCII graphic (that means output through console or writing to a file).
### Examples
Let us consider the following \$2\times 2\times 2\$ arrays:
```
[
 [[0,0],
  [1,0]]
 [[1,1],
  [1,0]],
]
[
 [[0,0],
  [0,0]]
 [[1,1],
  [1,1]],
]
```
In this case the output should look like this (it does not look as good here as it does in code editors/consoles with less vertical space):
```
  +----+
 /    /|-+----+
+----+ |     /|
|    | +----+ |
|    | |    | +
+    + |    |/
|    | +----+
|    |/
+----+
    +----+----+
   /         /|
  +         + |
 /         /  +
+----+----+  /
|         | +
|         |/
+----+----+
```
An example for a \$12\times 12\times 12\$ input string can be found [here (pastebin).](http://pastebin.com/GBwSyuvp) A new example for a \$7\times 7\times 7\$ input string can be found [here.](http://pastebin.com/XZncYSTR)
### Specifications of the ASCII
Each corner of a voxel is represented by a `+` as long as there is any edge leading to it. The `+` are also drawn when there is a straight edge that is more than one unit long. There are three types of edges: The horizontal left to right `----`, the horizontal back to front `/` and the vertical
```
|
|
```
Each of those has to end in a `+` (as long visible). The edges will not be drawn when they subdivide one planar plane into two or more pieces (unlike the `+` in relation to the edges as stated above). Structures that are hidden behind others must not be drawn.
The 'drawing' is basically a parallel projection so only top, right and front sides are visible - always from the same angle.
### Details
The code must be working for inputs of size \$n=1,2,\ldots,12\$. Trailing spaces and unnecessary newlines before/after are allowed (so you *could* write a code that always basically outputs the \$12\times 12\times 12\$ grid even when the actual size of the drawing is only \$3\times 3\times 3\$ or so).
Input formatting and method is up to you, you can use csv, JSON or any other stuff, but it has to consist of \$1\$ and \$0\$ for the state of each voxel. The order must be as in the examples:
* 1st dimension: layer by layer from the uppermost to the lowermost
* 2nd dimension: row by row back (furthest away) to front (nearest)
* 3rd dimension: voxels in each row left to right
Whether you use console or reading files as input and output is up to you. **Please** tell us about your code / how you approached it.
### Judging
This is codegolf so the fewest number of bytes wins. This includes ONLY the part that actually does the work - when counting bytes you can consider the input already as parsed and saved in a variable and you have to have the output string saved to a variable, ready to be printed. The parsing and the output itself does not count.
(And I will upvote submissions with creative examples=)
This was inspired by [Rob's Puzzle page](http://www.robspuzzlepage.com/interlocking.htm).
  
[Answer]
# Lua (1442 bytes)
**Bonus animations! :)**  
*If you have any cool voxel art in the same format as the examples, link it in the comments and I'll make an animation out of it*  
7x7x7  
![Bonus animation](https://i.stack.imgur.com/yi8Vl.gif)  
12x12x12  
![Bonus 2](https://i.stack.imgur.com/AS5tm.gif)  
This is my first code golf, so its quite messy and I plan on improving it or porting it to a different language.  
Here is what i have, right now at just under 2.5kB barely-golfed (just removed indentation whitespace at this point, I will continue more later)
Here is the now ~1.4kB golfed and minified version (note the "a" table on the first line is the placeholder for the voxel matrix):
```
local a={}
local b,c=table,string;local d,e,f,g,h,i=b.concat,#a,c.gsub,c.gmatch,ipairs,b.insert;local function j(k,l,m)return a[k]and a[k][l]and a[k][l][m]==1 end;local n={}for o=1,e*5+1 do n[o]={}for p=1,e*7+1 do n[o][p]=" "end end;local q=[[
__6hhhh7
_g    ij
1aaaa2 j
b    d 5
b    de_
3cccc4__
]]local function r(k,l,m)local s=q;if j(k,l,m)then local t,u,v,w,x,y,z,A=j(k-1,l,m),j(k+1,l,m),j(k,l,m-1),j(k,l,m+1),j(k,l-1,m),j(k+1,l+1,m),j(k+1,l,m+1)," "if t then s=f(s,"[ai]"," ")end;if u and not y then A=A.."c"end;if u and not z then A=A.."e"end;if v then A=A.."bg"end;if w then A=A.."di"end;if x then if not j(k,l-1,m+1)then A=A.."j"end;A=A.."h"end;if t then if w and j(k-1,l,m+1)then A=A.."2"end;if v and j(k-1,l,m-1)then A=A.."1"end end;if u then if w and j(k+1,l,m+1)then A=A.."4"end;if v and j(k+1,l,m-1)then A=A.."3"end end;if x then if w and j(k,l-1,m+1)then A=A.."7"end;if v and j(k,l-1,m-1)then A=A.."6"end;if u and j(k+1,l-1,m)then A=A.."5"end end;s=f(f(f(f(f(s,"["..A.."]"," "),"[ach]","-"),"[bdj]","|"),"[gie]","/"),"[1234567]","+")else s=nil end;return s end;local B,C;local D=e*2-1;local E=1;for k=e,1,-1 do for l=1,e do for m=1,e do B=(l-1)*-2+(m-1)*5+D;C=(l-1)*2+(k-1)*3+E;local s=r(k,l,m)if s then local F={}for G in s:gmatch("[^\n]+")do local H={}for I in G:gmatch(".")do i(H,I)end;i(F,H)end;for J,K in h(F)do for L,I in h(K)do if I~="_"then n[C+J-1][B+L-1]=I end end end end end end end;for o,a in h(n)do print(d(a))end
```
**Edit**: Here is the original (over 3kB) ungolfed version, including my edits for making the animation (if you are running it yourself and want the animation, change the `false` near the bottom of the code to `true`.
```
local v = {}
local depth = #v;
function voxel(y,z,x)
  return (v[y] and v[y][z] and v[y][z][x]==1)
end
local canvas = {}
print("Constructing canvas of depth",depth)
for i=1,depth*5+1 do
  canvas[i] = {}
  for j=1,depth*7+1 do
    canvas[i][j] = " "
  end
end
local voxelProto = [[
__6hhhh7
_g    ij
1aaaa2 j
b    d 5
b    de_
3cccc4__
]]
function renderVoxel(y,z,x)
  local vox = voxelProto
  if (voxel(y,z,x)) then
    local up = voxel(y-1,z,x)
    local down = voxel(y+1,z,x)
    local left = voxel(y,z,x-1)
    local right = voxel(y,z,x+1)
    local back = voxel(y,z-1,x)
    local downFront = voxel(y+1,z+1,x)
    local downRight = voxel(y+1,z,x+1)
    if (up) then
      vox = vox:gsub("[ai]"," ")
    end
    if (down and not downFront) then
      vox = vox:gsub("[c]"," ")
    end
    if (down and not downRight) then
      vox = vox:gsub("[e]"," ")
    end
    if (left) then
      vox = vox:gsub("[bg]"," ")
    end
    if (right) then
      vox = vox:gsub("[di]"," ")
    end
    if (back and not voxel(y,z-1,x+1)) then
      vox = vox:gsub("[j]"," ")
    end
    if (back or up) then
      vox = vox:gsub("[h]"," ")
    end
    if (up and right and voxel(y-1,z,x+1)) then
      vox = vox:gsub("[2]"," ")
    end
    if (up and left and voxel(y-1,z,x-1)) then
      vox = vox:gsub("[1]"," ")
    end
    if (down and right and voxel(y+1,z,x+1)) then
      vox = vox:gsub("[4]"," ")
    end
    if (down and left and voxel(y+1,z,x-1)) then
      vox = vox:gsub("[3]"," ")
    end
    if (back and right and voxel(y,z-1,x+1)) then
      vox = vox:gsub("[7]"," ")
    end
    if (back and left and voxel(y,z-1,x-1)) then
      vox = vox:gsub("[6]"," ")
    end
    if (back and down and voxel(y+1,z-1,x)) then
      vox = vox:gsub("[5]"," ")
    end
    vox = vox:gsub("[ach]","-")
    vox = vox:gsub("[bdj]","|")
    vox = vox:gsub("[gie]","/")
    vox = vox:gsub("[1234567]","+")
  else
    vox = nil
  end
  return vox
end
local xpos,ypos
local minx = depth*2-1
local miny = 1;
local pic = {}
function drawCanvas()
  for k,v in pairs(canvas) do
    pic[k] = table.concat(v)
  end
  return table.concat(pic,"\n")
end
local timeline = {}
print("Compositing voxels")
for y=depth,1,-1 do
  for z=1,depth do
    for x = 1,depth do
      xpos = (z-1)*-2 + (x-1)*5 + minx
      ypos = (z-1)*2 + (y-1)*3 + miny
      local vox = renderVoxel(y,z,x)
      if (vox) then
        local vt = {}
        for line in vox:gmatch("[^\n]+") do
          local vtl = {}
          for c in line:gmatch(".") do
            table.insert(vtl,c)
          end
         table.insert(vt,vtl)
        end
        for ly,chars in ipairs(vt) do
          for lx,c in ipairs(chars) do
            if (c ~= "_") then
              canvas[ypos+ly-1][xpos+lx-1] = c
            end
          end
        end
        table.insert(timeline,drawCanvas())
      end
    end
  end
end
if (false) then -- change to true if you want to see the animation!
  for i=1,#timeline do
    local t = os.clock() + 0.05
    io.write(timeline[i],'\n\n')
    io.flush()
    while (t > os.clock()) do end
  end
end         
print(timeline[#timeline])
```
Here is a sample of code that will populate the voxel matrix from a string for a 3x3x3 voxel matrix. (It will take any string in a similar format, but make sure it is a cube or things will probably break.)  
To use this, insert this chunk right after the first line `local v = {}`
```
local vs = [[
100
000
000
110
100
000
111
110
101
]]
for layer in vs:gmatch("[^a]+") do
 local a = {}
 for row in layer:gmatch("[^\n]+") do
 local b = {}
 for _vox in row:gmatch("[01]") do
 table.insert(b,(_vox=="1") and 1 or 0)
 end
 table.insert(a,b)
 end
 table.insert(v,a)
end
```
Here is the output from [the given 12x12x12 voxel](http://pastebin.com/GBwSyuvp) pattern: (and yes it does look better on a normal console/text viewing apparatus, there is a bit too much vertical spacing here)
```
                                                                          +----+----+
                                                                         /         /|
                                                                        +----+----+ |
                                                                        |         | +
                                                            +----+      |         |/
                                                           /    /|      +    +----+
                                                          +----+ |      |    | +----+
                                                          |    | +      |    |/    /|
                                                          |    | |      +    +----+ |
                                                          +    + |      |         | +
              +----+----+                         +----+--|    | +      |         |/
             /         /|                        /        |    | |      +    +----+
            +----+----+ |                       +----+----+    + |      |    | +----+
            |         | +                       |              | +      |    |/    /|
            |         |/       +----+----+----+ |              | |      +    +----+ |
            +    +----+       /              /| +    +----+    + |      |         | +
            |    | +         +----+----+----+ | |    | +--|    | +      |         |/
            |    | |         |              | + |    |/   |    | |      +----+----+
            +    + |         |              | | +    +----+    + |            
            |    | +         +    +----+    + | |              | +            
            |    | |         |    | +--|    | + |              |/             
            +    + |         |    |/   |    | | +----+----+----+              
            |    | +----+    +    +----+    + |                               
            |    |/    /|    |              | +                               
            +    +----+ |    |              |/                                
            |         | +    +----+----+----+                                 
            |         |/                                                      
            +----+----+                                       +----+----+     
                                                             /         /|     
                                                  +----+    +----+----+ |     
                                                 /    /|    |         | +     
                                                +----+ |    |         |/      
                                                |    | +    +    +----+       
      +----+----+----+  +----+----+----+----+---|    | |---+|    | +----+-+----+----+
     /              /| /                        +    + |    |    |/    /|          /|
    +----+----+----+ |+                         |    | +    +    +----+ |         + |
    |              | +                          |    | |    |         | +        /  +
    |              | |      +----+----+----+    +    + |    |         |/        +  /
    +    +----+    + |     /              /|    |    | +    +    +----+        /  +
    |    | +--|    | +    +----+----+----+ |    |    | |    |    | +          +  /
    |    |/   |    | |    |              | +    +    + |    |    | |         /  +
    +    +----+    + |    |              | |    |    | +    +    + |        +  /
    |              | +    +    +----+    + |    |    | |    |    | +       /  +
    |              | |    |    | +--|    | +    +    + |    |    |/       +  /
    +----+----+    + |    |    |/   |    | |    |    | +    +----+       /  + 
      +----+--|    | +    +    +----+    + |    |    |/                 +  /  
     /        |    | |    |              | +    +----+                 /  +   
    +----+----+    + |    |              |/                           +  /    
    |              | +    +----+----+----+                           /  +     
    |              |/                                               +  /      
    +----+----+----+                                               /  +       
      +                                                           +  /        
     /                                                           /  +         
    +                                                           +  /          
   /                                                           /  +           
  +                                                           +  /            
 /                                                           /  +             
+----+----+----+----+----+----+----+----+----+----+----+----+  /              
|                                                           | +               
|                                                           |/                
+----+----+----+----+----+----+----+----+----+----+----+----+   
```
Here is the output from [the 7x7x7 example here](http://pastebin.com/XZncYSTR)
```
              +----+----+----+    +----+----+----+
             /              /|   /              /|
            +    +----+    + |  +    +----+    + |
           /    /|   /    /  + /    /|   /    /  +
          +    + |  +    +  / +    + |  +    +  / 
         /    /  +-/    /  + /    /  +-/    /  +  
        +----+  /-+----+  /-+----+  /-+----+  /--+
        |    | +  |    | +  |    | +  |    | +  /|
      +----+ | |+----+ | |+----+ | |+----+ | | + |
     /    /| + /    /| + /    /| + /    /| + |/  +
    +    + | |+    + | |+    + | |+    + | | +   |
   /    /  + /    /  + /    /  + /    /  + |   + |
  +    +----+    +   |+    +----+    +   | +  /| +
 /              /  + /              /  + | | + | |
+----+----+----+  /|+----+----+----+  /| + |/--+ |
|              | + ||              | + | |-+  /  +
|              |/--+|              |/--+ |   +  / 
+----+----+----+  / +----+----+----+  /  +  /  +  
  +    +  / +    +----+    +  /-+    +  /--+  /--+
 /    /  + /              /  + /    /  +   | +  /|
+----+  / +----+----+----+  /-+----+  /--+ |/  + |
|    | +  |              | +  |    | +  /|-+  /  +
|    | |-+|              |/  +|    | | + |   +  / 
+    + |  +----+----+----+  /|+    + |/  +  /  +  
|    | +----+----+ | |+    + ||    | +  /--+  /   
|    |/         /| + /    /  +|    |   +   | +    
+    +----+----+ | |+----+  /-+    +  /--+ |/     
|              | + ||    | +  |    | +  /|-+      
|              | | +|    | | +|    |/  + |        
+----+----+    + | |+    + |/|+----+  /  +        
  +    +--|    | + ||    | + |  +    +  /         
 /        |    | |-+|    |   +-/    /  +          
+----+----+    + |  +    +  / +----+  /           
|              | +  |    | +  |    | +            
|              |/   |    |/   |    |/             
+----+----+----+    +----+    +----+              
```
[Answer]
# Python ( 444 361 354 bytes)
*Edit:* I found another bug that would omit a corner cross in very special cases. A straight forward fix added 50 bytes to the code so I tried to golf it down a bit further. Now the bug is fixed and it's even 83 bytes shorter. It's becoming very hacky. I also wanted to get rid of the fivefold for loop but could not yet find a solution. Any ideas?
*Edit 2:* With a very long import I can save another 7 characters.
Neither very short nor very elegant, but then again it is a complex problem:
```
#input:
u=[[[1,1,1],[1,0,1],[1,1,1]],
   [[1,0,1],[0,0,0],[1,0,1]],
   [[1,1,1],[1,0,1],[1,1,1]]]
#actual code that counts:
r=range
n=len(u)
g=r(n)
a=([' ']*9*n+['\n'])*6*n
t='/|-+\n '
d=dict(zip(t+'%!=*',2*t))
for y,z,x,i,j in __import__('itertools').product(g,g,g[::-1],r(6),r(8)):
 if abs(i+j-6)<5*u[x][y][z]:a[(9*n+1)*(i+3*x+2*y)+j+5*z-2*y+2*n]+='./    %|+====* ||    ! *|    !/.*----+'[8*i+j-8]
o=''.join((d[x[-1]],' ')[x[-2:]in('%/','!|','=-')or x[-4:]=='*++*']for x in a)
#output:
print o
```
It first draws all the individual voxels with all lines on top of each other. Then it outputs only the topmost characters and gets rid of those lines and crosses on planar planes that should not be drawn according to the specs.
I guess it's possible to golf this down quite some more, but 444 is such a nice number. :)
Example 3x3x3 and 7x7x7 output (with some newlines removed):
```
        +----+----+----+   
       /              /|   
      +    +----+    + |   
     /    /|   /    /  +   
    +    +----+    +   |   
   /              /  + |   
  +----+----+----+  /| +   
  |              | + | |   
  |              | |-+ |   
  +    +----+    + |/  +   
  |    | +--|    | +  /    
  |    |/   |    |   +     
  +    +----+    +  /      
  |              | +       
  |              |/        
  +----+----+----+         
                +----+----+----+    +----+----+----+           
               /              /|   /              /|           
              +    +----+    + |  +    +----+    + |           
             /    /|   /    /  + /    /|   /    /  +           
            +    + |  +    +  / +    + |  +    +  /            
           /    /  +-/    /  + /    /  +-/    /  +             
          +----+  /-+----+  /-+----+  /-+----+  /--+           
          |    | +  |    | +  |    | +  |    | +  /|           
        +----+ | |+----+ | |+----+ | |+----+ | | + |           
       /    /| + /    /| + /    /| + /    /| + |/  +           
      +    + | |+    + | |+    + | |+    + | | +   |           
     /    /  + /    /  + /    /  + /    /  + |   + |           
    +    +----+    +   |+    +----+    +   | +  /| +           
   /              /  + /              /  + | | + | |           
  +----+----+----+  /|+----+----+----+  /| + |/--+ |           
  |              | + ||              | + | |-+  /  +           
  |              |/--+|              |/--+ |   +  /            
  +----+----+----+  / +----+----+----+  /  +  /  +             
    +    +  / +    +--- +    +  /-+    +  /--+  /--+           
   /    /  + /              /  + /    /  +   | +  /|           
  +----+  / +----+----+----+  /-+----+  /--+ |/  + |           
  |    | +  |              | +  |    | +  /|-+  /  +           
  |    | |-+|              |/  +|    | | + |   +  /            
  +    + |  +----+----+----+  /|+    + |/  +  /  +             
  |    | +----+----+ | |+    + ||    | +  /--+  /              
  |    |/         /| + /    /  +|    |   +   | +               
  +    +----+----+ | |+----+  /-+    +  /--+ |/                
  |              | + ||    | +  |    | +  /|-+                 
  |              | | +|    | | +|    |/  + |                   
  +----+----+    + | |+    + |/|+----+  /  +                   
    +    +--|    | + ||    | + |  +    +  /                    
   /        |    | |-+|    |   +-/    /  +                     
  +----+----+    + |  +    +  / +----+  /                      
  |              | +  |    | +  |    | +                       
  |              |/   |    |/   |    |/                        
  +----+----+----+    +----+    +----+                         
```
]