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Re: Website update
| Re: Website update [message #38080] |
Thu, 19 February 2004 11:04  |
Rick Towler
Messages: 821
Registered: August 1998
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Senior Member |
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"Paul van Delst" wrote...
> Rick Towler wrote:
>>
>> About two years ago I put up a few skimpy web pages offering up my
object
>> graphics camera class and directInput DLM with a promise to add more. I
>> have *finally* found the time to update these web pages. Highlights:
>>
>> RHTgrCamera
>
> <snip>
>
>> There is a new demo available too which demonstrates view frustum
culling,
>
> "view frustum culling"?? Wha...?
>
> I feel old.
Either you feel old or I feel foolish. There are days where I think view
frustum culling in IDL (as I have implemented it) is like tricking out a '74
pinto. Lift kit for the back... Some nice chrome rims...
View frustum culling is a method of limiting the number of polygons pushed
down the rendering pipeline by testing objects for intersection with the
viewing frustum. If objects intersect they are rendered, if not they
aren't. The view frustum is the truncated pyramid that defines the space
where your object graphics objects are rendered.
For example, if you had a large very high resolution DEM and you wanted to
do a fly thru of a drainage you would construct the 3d model by creating it
out of smaller tiles, say 40x40 polygon objects. These objects could be
added as culled content to the camera. For every frame that is rendered the
camera would check which objects intersect the frustum and set these objects
HIDE properties accordingly. If your view is set such that you only ever
see a subset of the 40x40 objects you get a nice gain in performance
compared to the brute force approach.
Now all 4 people using my camera can enjoy this feature :)
-Rick
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