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                 *** Tempest's BUILD Tutorial ***
               Lesson 3 : Making swinging doors
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Purpose:
   A tutorial on swinging doors in Duke Nukem 3D using Build.

Step 1:
   Make a door opening. Choose some cool textures.

Step 2:
   Now create a sector that is to be used as the door.
   Notice that the door sector is not connected to any other sector.

Step 3:
   Move the door sector into position. Notice that the vertices of
   the door will not connect to the vertices of the wall. Make
   sure they aren't connected by moving the vertices around.

Step 4:
   Give the door sector a Lo-tag value of 23. Now comes the crucial
   part. You will have to define a pivot point that the door will turn 
   around. Create a sector effector sprite (sprite #1) and put it in 
   a logical place. Remember that the door sector must rotate around 
   the sector effector. The SE (Sector Effector) MUST BE INSIDE THE
   DOOR SECTOR!!! Do not put the SE on a door vertex, but near it.
   Undo grid locking by pressing 'L' in 2D-mode and move the SE as
   close as possible to a door vertex without going outside the door
   sector. If you want the door to open clockwise, make the SE point
   downwards. If the door needs to open counter-clockwise, make the
   SE point upwards. Use the < and > keys to rotate the sprite.
   That's it! You now have a swinging door! Add a Music & SFX sprite
   (sprite #5) for door sounds. In this example I made the M&SFX
   sprite Lo-tag and Hi-Tag values of 165. (Change the Lo-tag value
   by pressing 'Alt-T'. Use 'Alt-H' for changing the Hi-Tag value).

NB: 
   Your door is initially placed inside some sector. You must take
   care that the door stays inside this sector, even when opened!
   You will get strange effects when your door opens onto another
   sector than the one it was originally placed in. Beware!!!

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 Cho Yan Wong (aka Tempest)
 pwong@pobox.leidenuniv.nl
 http://www.wi.leidenuniv.nl/~cwong/myindex.html 
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