[osg-users] Using OsgSim Overlay

Vaibhav Bansal vaibhav at darshan3d.com
Thu Nov 19 04:29:02 PST 2009


Yes, this is what the overlay node does for me.
But I am unable to understand, why the stretching occurs only 'at' some
specific angles.

Regards
Vaibhav Bansal

-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org
[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of J.P.
Delport
Sent: Thursday, November 19, 2009 3:47 PM
To: OpenSceneGraph Users
Subject: Re: [osg-users] Using OsgSim Overlay

Hi,

Vaibhav Bansal wrote:
> Hello jp,
> 
> Thanks for the quick reply.
> How do I check if the 'resolution' of ovelay geometry is changing.

imagine the following:
You want to overlay a 1024x1024 checkerboard onto the earth and you have 
a 512x512 overlay texture. If you view the whole earth it obviously 
would not look good - too much detail to fit into the texture. What the 
view dependent modes try to do is this: When you zoom in, you only see a 
piece of the checkerboard, so now the 512x512 texture can contain only a 
piece of the checkerboard and so you see "more detail" of the overlayed 
geometry.

I think this is the effect you are seeing when you are moving the view 
around.

jp

> 
> Regards
> Vaibhav Bansal
> 
> -----Original Message-----
> From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of J.P.
> Delport
> Sent: Thursday, November 19, 2009 2:41 PM
> To: OpenSceneGraph Users
> Subject: Re: [osg-users] Using OsgSim Overlay
> 
> Hi Vaibhav,
> 
> Vaibhav Bansal wrote:
>> Hello,
>>  
>> I have added a geometry as an overlay over another geometry.
>> The overlay texture seems to distort(stretch) under certain viewing
> angles.
>> It seems the projected texture is generating incorrect texture
> coordinates.
> 
> The texture coordinates might be OK, but the resolution of your 
> overlayed geometry might change in the generated overlayed texture. What 
> happens in OBJECT_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY? Does the 
> resolution/stretch stay the same?
> 
> jp
> 
>> The white area is the overlaySubgraph geometry, and the colored area is
> the
>> Overlay Node (base) geometry.
>> The overlay mode is VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_PROJECTION.
>>
>> Can anyone suggest where should I start troubleshooting.
>>
>> Thanks
>> Vaibhav Bansal
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>> ------------------------------------------------------------------------
>>
>>
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>>
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> 

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