Hi Terry,
On 1/8/07, Terry Welsh <[EMAIL PROTECTED]> wrote:
> Hi Chris,
> These PagedLOD holes were the main reason I have given up on writing a
> simple Metaflight loader (I emailed the list about that this morning).
> You're right; subclassing PagedLOD was very difficult. I was trying
> to use a NodeVisitor to seek out PagedLODs with unloaded data, and
> it's just too much of a headache.
>
> For now it looks like I'll have to give up on a simple MetaFlight
> loader and complicate the code by adding my own paging utility (maybe
> based on NodeVisitor::DatabaseRequestHandler, or maybe not. I haven't
> decided yet). If you have any other thoughts on the subject I'd be
> glad to hear them.
It's sad to hear you giving up. Unfortunately I'm swamped with work,
and don't have any knowledge about the specific requirements of
MetaFlight to be able to help.
MetaFlight is pretty simple geometrically (much simpler than txp from
what I understand). My fundamental problem is that LOD and PagedLOD
want to switch which children are traversed as soon as the eye
distance changes. I need to delay these switches until the proper
geometry is loaded, and there is no functionality built into OSG for
doing this.
It certainly is possible to get things loading without holes with the
appropriate contruction of the scene graph - this is just what osgdem
does. The txp plugin also work just fine, but txp adds a number of
extra steps on top of standard paging to ensure the correct LOD's on
tile boundaries are selected w.r.t what data is paged in. Perhaps the
txp plugin might offer some insight.
I've looked at the txp loader a bit, but it's a very complicated and
undocumented loader. Unfortunately, I don't have enough time to
figure out all its extra steps and if they apply to my problem at the
moment.
- Terry
Robert.
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