Knowledge Base - Sky Window
A sky window is, as the name implies, a window that the player can see the sky texture, when looking out the window. Used in combination with the skybox, a sky window can give a level a feeling of realism. The skybox sample wad illustrates the use of a sky window.
The sky window is easy to make once the you understand the procedure. Figure 2 shows a typical layout.
Sector A is the windowsill, the visible portion of the window. This sector determines how large the window will be. As in creating any opening in a sector be sure to unpeg both the upper and lower textures of the linedef that faces into the room.
Sector B is the transition portion of the window. The floor and ceiling heights are the same as sector A, however the ceiling texture here is F_SKY. The floor texture is the same texture used in sector A. This sector is needed so that the window has the proper depth.
Sector C is the actual sky sector. The floor and ceiling have the same height, the floor height of sectors A and B. Both floor and ceiling texture here are F_SKY. By making the floor and ceiling a sky with the same height you create a seamless vista of sky through out the sector.
The end result is a natural looking window that looks out into the sky of the level. By combining the sky window with a skybox, you can elaborate vistas that can enhance the appearance of your level.