蓝色可以表示冬季，绿色表示春季，黄色表示夏季，红色表示秋季。

 

再上几张图：

从正顶向下看：

 

从侧下向上看

 

进到胎里面看：

 

 

附：

环面构造的图形学算法。其实，就是根据环面的参数方程算出每点的(x,y,z)。

 

u = 6.28
For u = 0 To 6.28 Step du
  For v = 0 To 6.28 Step dv
      xx = (100# + r * Cos(u)) * Cos(v)
      yy = (100# + r * Cos(u)) * Sin(v)
      zz = 100# + r * Sin(u)
      x1 = xx * Cos(cy) + zz * Sin(cy) + 200
      y1 = xx * Sin(cy) * Sin(cx) + yy * Cos(cx) _
           - zz * Cos(cy) * Sin(cx) + 200
      z1 = -xx * Sin(cy) * Cos(cx) + yy * Sin(cx) _
           + zz * Cos(cy) * Cos(cx)
     
      xx = (100# + r * Cos(u)) * Cos(v + dv)
      yy = (100# + r * Cos(u)) * Sin(v + dv)
      zz = 100# + r * Sin(u)
      x2 = xx * Cos(cy) + zz * Sin(cy) + 200
      y2 = xx * Sin(cy) * Sin(cx) + yy * Cos(cx) - _
           zz * Cos(cy) * Sin(cx) + 200
      z2 = -xx * Sin(cy) * Cos(cx) + yy * Sin(cx) + _
           zz * Cos(cy) * Cos(cx)
 
      xx = (100# + r * Cos(u + du)) * Cos(v + dv)
      yy = (100# + r * Cos(u + du)) * Sin(v + dv)
      zz = 100# + r * Sin(u + du)
      x3 = xx * Cos(cy) + zz * Sin(cy) + 200
      y3 = xx * Sin(cy) * Sin(cx) + yy * Cos(cx) - _
           zz * Cos(cy) * Sin(cx) + 200
      z3 = -xx * Sin(cy) * Cos(cx) + yy * Sin(cx) + _
           zz * Cos(cy) * Cos(cx)
 
      xx = (100# + r * Cos(u + du)) * Cos(v)
      yy = (100# + r * Cos(u + du)) * Sin(v)
      zz = 100# + r * Sin(u + du)
      x4 = xx * Cos(cy) + zz * Sin(cy) + 200
      y4 = xx * Sin(cy) * Sin(cx) + yy * Cos(cx) - _
           zz * Cos(cy) * Sin(cx) + 200
      z4 = -xx * Sin(cy) * Cos(cx) + yy * Sin(cx) + _
           zz * Cos(cy) * Cos(cx)
         xx1 = x2 - x1: xx2 = x3 - x1        
         yy1 = y2 - y1: yy2 = y3 - y1
         zz1 = z2 - z1: zz2 = z3 - z1 
         x = yy1 * zz2 - yy2 * zz1
         y = zz1 * xx2 - zz2 * xx1
         z = xx1 * yy2 - xx2 * yy1
        If (z > 0) Then
           xd(0) = x1: yd(0) = y1
           xd(1) = x2: yd(1) = y2
           xd(2) = x3: yd(2) = y3
           xd(3) = x4: yd(3) = y4
           dd = -(x * x1 + y * y1 + z * z1)
           Call tc(4, 100)   //不要管这句，这句是调用光照渲染算法的。
        End If
      Next
   Next
End Sub