Re: [Algorithms] Leafy BSP Tree Contruction

[Adrian B. <ad...@gm...>]

I seem to remember a thread about this, try searching the archives
(you might need to search Sweng Gamedev too).

One thing important for good results is to generate the plane from the
source triangle and just reference it from all polygons split from
that triangle, that way splitting doesn't dirty your plane equation.
Try combining that with penalizing splitting planes with other
parallel triangles and higher precision math.

Also, Real Time Collision Detection contains a some good guidelines on
"fat" bsp construction (using epsilons and such).  IIRC the key
involves treating transitions from/to side A/B and On in a logically
consistent way so slivers are never created.  You can probably derive
them yourself, but it does take lots of diagrams and brain mangling
about degenerate cases.

Cheers,
Adrian

On Tue, May 19, 2009 at 12:01 PM, Manolache Adrian <pro...@ya...> wrote:
>              During the bsp tree compilation there happens sometimes that a
> polygon would be split so much until it becomes very thin with an area
> almost 0. This polygon would further be split and thus obtaining degenerate
> triangles. The problem is that the construction fails when fed this kind of
> polygons and full leaves(all polygons used as splitter) arive in back nodes.
> When clipping triangles or classifying them i used a small epsilon to
> compare to 0(absolute tolerance test). How can i go around avoiding
> degenerate triangle creation, how can these be handled? Is it the sole duty
> of the artist to avoid such cases?
>
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