Re: [Flightgear-devel] Query about groundradar Instrument module

[Ron J. <wi...@je...>]

On Thursday 29 September 2011 14:32:54 Robbo wrote:
> Hi,
>
> I am trying to familiarise myself with Flightgear's source code so that I
> may try and contribute.  I am currently looking at the 'groundradar'
> instrument module and there is something within that is causing me some
> confusion.
>
> Essentially, there is a 'texture' declared as follows:
> static const char* default_texture_name =
> "Aircraft/Instruments/Textures/od_groundradar.rgb";
>
> This is then used by the following method:
> void GroundRadar::createTexture(const char* texture_name)
>
> in the following way:
> FGTextureManager::addTexture(texture_name, getTexture());
>
> Now all is good at this point until I go and look for this file, which i
> expected to find in data/Aircraft/Instruments/Textures/, however, this file
> does not appear there, nor does it appear anywhere else on my filesystem
> either.
>
> I thought, well maybe the code is not actually using this texture, since
> its a 'default_texture', however, when i change the name to point to
> something else which also does not exist, then, the once black background
> becomes white!
>
> So I am assuming that this file MUST be somewhere, but I have no idea where
> it is, can anyone assist me with this?
>
> Thanks
>
> Robbo

Definitely  not my area, but...

The hint for me was the call 'createTexture()' opposed to load or get 
Texture(). I believe we are doing a render-to-texture thing. If you grep for 
Aircraft/Instruments/Textures/od_groundradar.rgb in fgdata/Aircraft you get 
many hits like:
ATC/radar-screen.xml:                                
<path>Aircraft/Instruments/Textures/od_groundradar.rgb</path>

So, if I understand things correctly, the models are asking for a texture by 
name, which is created by GroundRadar::createTexture() instead of being 
loaded from disk.

Ron