[Papervision3D] Games and Stories AND clipping

[Tim Knip]

Have some experience with BSP-trees....

Works great for scenes where there's big difference in triangle size.
Its cool for z-sorting a scene (and for things like collision detect).
Can confirm it works great in as2 and as3...

Main disadvantage of BSP-trees is that some faces need to be split,
resulting in about 1.5 times the original polycount. Advantage is that
creating the BSP-tree is an offline process.
As Jon mentioned above, moving stuff is somewhat more difficult to implement.

Now, you may know that Quake uses a BSP-tree too... Quake uses the
BSP-tree not for z-sorting (as OpenGL takes care of this) but mainly
for collision-detection.

Quake though has some other nifty optimizing tricks: the so-called
Possible Visible Set (PVS). Its a rather large data structure which
determines the possible visible faces for each other face. Say the
camera is 'on' face X, then the PVS lets you know which other faces
are possibly visible. Problem of course is how to create this set
(normally one uses some Quake level editor)...

Furthermore Quake uses 'portals' => when you're inside a room,
everything outside the room won't be visible..

Anyways: Quake / Quake2 code is good read!

Have a good year all!

Tim K