How is does the bounding work? (Message 1 to 3 of 3)
From: Ari-Matti Leppanen
Subject: How is does the bounding work?
Date: 11 Apr 2002 16:46:47
Message: <3cb5f637$1@news.povray.org>
If you make a simple and pointless merge like
merge{
box { -1, 1 }
sphere { y, 1 }
bounded_by { cylinder { -y, 2*y, sqrt(2)} }
}
and trace it:
-------------------------------------------------
Box 957 504 52.66
Cone/Cylinder 957 957 100.00
CSG Merge 957 684 71.47
Sphere 957 448 46.81
Bounding Object 957 957 100.00
Bounding Box 78450 1914 2.44
-------------------------------------------------
the stats show intersection tests against a bounding object and a bounding
box. Why the bbox when the shape is already bounded manually?
Ari-Matti
From: Slime
Subject: Re: How is does the bounding work?
Date: 11 Apr 2002 17:59:16
Message: <3cb60734$1@news.povray.org>
> the stats show intersection tests against a bounding object and a bounding> box. Why the bbox when the shape is already bounded manually?
I'm willing to bet that the ray first tests to see if it hits the bounding
box of the bounding object. If it does, then it tests to see if it hits the
bounding object. If it does, then it tests to see if it hits the object
itself.
This probably speeds it up a bit, since you could technically specify an
isosurface or other slow-to-render object as the bounding object if you
wanted, and testing the bounding box of *that* object may speed up the
render.
Just a guess.
- Slime
[ http://www.slimeland.com/ ]
[ http://www.slimeland.com/images/ ]
From: Ari-Matti Leppanen
Subject: Re: How does the bounding work?
Date: 12 Apr 2002 02:31:43
Message: <3cb67f4f@news.povray.org>
"Ari-Matti Leppanen" <ari### [at] ThisShouldBeRemovedtutfi> wrote
in message news:3cb5f637$1@news.povray.org...
> the stats show intersection tests against a bounding object and a bounding> box. Why the bbox when the shape is already bounded manually?
Answering to myself: In the sorce of 3.1g it looks like the root node of the
bounding tree is bounded by a box big enough to contain all objects in the
tree, so that could be the reason.
tut