Xmin = -3
Xmax = -0.5
Ymin = -3
Ymax = -0.5

A = [0,0,0]
B = [1,0,0]
C = [1,1,0]
D = [0,1,0]

E = [0,0,1]
F = [1,0,1]
G = [1,1,1]
H = [0,1,1]

a = 0
eps = 0.005

setInterval(function (){ inter() },50)

function inter(){
  effaceEcran()
  couleur = noir
  segment(A,B,[3,3])
  segment(B,C)
  segment(C,D)
  segment(D,A,[3,3])
  segment(A,E,[3,3])
  segment(B,F)
  segment(C,G)
  segment(D,H)
  segment(E,F)
  segment(F,G)
  segment(G,H)
  segment(H,E)

if(3*a<1 && 3*a > 0){
    point([3*a,0,0])
    point([0,3*a,0])
    point([0,0,3*a])
    peinture = vert
    transparence = 0.3
    poly([[3*a,0,0],[0,3*a,0],[0,0,3*a]])
  }
  if(3*a-1<1 && 3*a-1 > 0){
    point([1,3*a-1,0])
    point([3*a-1,1,0])
    point([3*a-1,0,1])
    point([0,3*a-1,1])
    point([1,0,3*a-1])
    point([0,1,3*a-1])
    peinture = vert
    transparence = 0.3
    poly([[1,0,3*a-1],[1,3*a-1,0],[3*a-1,1,0],[0,1,3*a-1],[0,3*a-1,1],[3*a-1,0,1]])
  }
  if(3*a-2<1 && 3*a-2 > 0){
    point([3*a-2,1,1])
    point([1,3*a-2,1])
    point([1,1,3*a-2])
    peinture = vert
    transparence = 0.3
    poly([[3*a-2,1,1],[1,3*a-2,1],[1,1,3*a-2]])
  }
  
  if( a > 1.2 ){ eps = -0.01; }
  if( a < -0.2 ){ eps = 0.01; }
  a = a + eps
}