[osg-users] Using OsgSim Overlay

J.P. Delport jpdelport at csir.co.za
Thu Nov 19 07:12:34 PST 2009


Hi,

Vaibhav Bansal wrote:
> 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.

Are the transitions smooth or are you seeing jumps?

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 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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