On Sat, 20 May 2000 00:12:07 -0700, "Dave Blandston"
<gra### [at] earthlinknet> wrote:

>I made a scene of a stone wall. The stones were created as individual
>objects (a couple hundred of 'em), and the scene rendered properly in about
>30 minutes at 1024x768 resolution. I decided to make a single "BrickWall"
>object (using a macro) that was a union of all the individual stones, and
>suddenly it took almost NINE HOURS to render the same scene, although it
>looked the same! Did I do something wrong? Is there a solution to this
>problem? I would like to keep the union so that I can easily manipulate
>multiple stone walls in my scene.

Dave,

I didn't have much time to test your code but here's the little I have
found so far:

1. Antialiasing slows it down immensely
2. Manuallly bounding each NewBrick object in a unit box gives a
10-20% speedup

POV reports 2 frame level objects and these are the two walls. I
haven't ventured deep in your code (though, I must admit, it is among
the top five I've seen, style-wise) but I found that a wall is a CSG
intersection of a box and the union of the mortar and bricks. This
makes it one object in terms of bounding so even with the vista buffer
on POV has to test 30% of the images on the screen against all stones,
which are CGSs of superellipsoids and height fields. I am pretty sure
that if, instead of intersecting above box with the union of the
bricks, you make a union of the intersections of this box with every
single brick, it will speed up the render considerably, because every
brick will then be bounded individually and rays will only be tested
against it when necessary.

There might be other optimisations to make, like using clipped_by
instead of intersection etc. but if what I propose works as I hope it
would, you'll have more time to experiment with extra speedup tweaks.

Hope it works...


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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