Re: [Plib-devel] Nested LOD selectors almost works...

[Steve B. <sjb...@ai...>]

"Vallevand, Mark K" wrote:
> 
> Nested LOD selectors almost works.
> 
> In my program, I recursively partition a tile into sub-tiles at
> at higher level of detail.  If a tile can be partitioned, I create
> a LOD selector with 2 kids - one for the lower level of detail
> tile and a second one that is a branch containing the higher
> level of detail sub-tiles.  Every thing works together really
> nice.  The tree seems to be correct, all the leaf nodes at all
> levels of details are correct, and their bounding spheres
> have the correct center and radius.  Lots of brute force
> debugging and print statements makes me believe things
> are correct.
> 
> But, the same debugging and print statements show me
> that the range calculated in the cull of each LOD selector
> is the same for each selector.  As I move the camera
> around the terrain, the range changes and I get different
> culling, but it is funny because the range calculated seems
> to be wrong.

Hmmm - the LOD range is measured to the local origin of the
model...so could it be that your terrain tiles all share
a common origin?

> So, my questions...
> How is the range calculated when culling to the viewing fustrum?

I don't calculate the range.  I transform the bounding sphere
center using the current modelview matrix and compare it to the
plane equations of the six clipping planes that make up the
view frustum.

-- 
Steve Baker                  http://web2.airmail.net/sjbaker1
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