Uses "TBGL"
  Global hWnd As Long, ax, ay As Single
  hWnd = TBGL_CreateWindowEx("ESC to exit; arrow keys to rotate", 1024, 768, 32, _
    %TBGL_WS_WINDOWED Or %TBGL_WS_CLOSEBOX)                      
  TBGL_ShowWindow
    
  Do While TBGL_IsWindow(hWnd) And _
      Not TBGL_GetWindowKeyOnce(hWnd, %VK_ESCAPE) 
    If  TBGL_GetWindowKeyState(hWnd, %VK_DOWN)  Then ax+= 1.44 ' 10sec/rev
    If  TBGL_GetWindowKeyState(hWnd, %VK_UP)    Then ax-= 1.44 
    If  TBGL_GetWindowKeyState(hWnd, %VK_RIGHT) Then ay+= 1.44 
    If  TBGL_GetWindowKeyState(hWnd, %VK_LEFT)  Then ay-= 1.44 
    TBGL_ClearFrame
    TBGL_Camera 1,1,4, 0,0,0
    TBGL_RotateXYZ ax, ay, 0    
    TBGL_Color 255,255,255
    TBGL_Line 0,0,0, 1,0,0 ' axes
    TBGL_Line 0,0,0, 0,1,0
    TBGL_Line 0,0,0, 0,0,1
    TBGL_Color 255,0,0  
    zrect     .1,.1,.1, .1,.2,.2 ' in yz plane                           
    TBGL_Rect .1,.1,.1, .1,.2,.2                            
    TBGL_Color 0,255,0
    zrect     .3,.3,.3, .4,.3,.4 ' in zx plane                           
    TBGL_Rect .3,.3,.3, .4,.3,.4 ' where is this rectangle?                            
    TBGL_Color 0,0,255  
    zrect     .5,.5,.5, .6,.6,.5 ' in xy plane                           
    TBGL_Rect .5,.5,.5, .6,.6,.5
    TBGL_DrawFrame            
    Sleep 40
  Loop 
  
' this sub draws outline only
Sub zRect(x1 As Single, y1 As Single, z1 As Single, _  
          x2 As Single, y2 As Single, z2 As Single)
  If x1=x2 Then ' in yz plane
    TBGL_BeginPoly %GL_LINE_LOOP
      TBGL_Vertex x1,y1,z1
      TBGL_Vertex x1,y2,z1
      TBGL_Vertex x1,y2,z2
      TBGL_Vertex x1,y1,z2
    TBGL_EndPoly  
  ElseIf y1=y2 Then ' in zx plane
    TBGL_BeginPoly %GL_LINE_LOOP
      TBGL_Vertex x1,y1,z1
      TBGL_Vertex x1,y1,z2
      TBGL_Vertex x2,y1,z2
      TBGL_Vertex x2,y1,z1
    TBGL_EndPoly  
  ElseIf z1=z2 Then ' in xy plane
    TBGL_BeginPoly %GL_LINE_LOOP
      TBGL_Vertex x1,y1,z1
      TBGL_Vertex x2,y1,z1
      TBGL_Vertex x2,y2,z1
      TBGL_Vertex x1,y2,z1
    TBGL_EndPoly  
  Else  
    TBGL_Line x1,y1,z1, x2,y2,z2
  End If
End Sub