Re: [Flightgear-devel] Ideas for terrain shader structure in 3.0

[Renk T. <tho...@jy...>]

> I've just pushed a change that allows a material definition in  
> materials.xml
> to include a <parameters> section, which is merged with the <parameters>
> section of the effect.  So you can now define parameters in the  
> materials.xml
> file that can be used as uniforms in the effects file, and therefore  
> shader.

Cool!

I've gone through the crop shader yesterday, and I think I have an idea that just might work:

The crop shader doesn't actually solve the tiling problem, it just shifts it to an 8 km scale instead of a 2 km scale, which is much less obvious. We could do the same thing:

* use an 8 (10,12?)-km sized mask of black and white
* if the mask is white, display one agricultural texture, if it is black a different one or the same rotated by 30 deg - that shifts tiling from 2 to 8 km
-> this needs obviously some handcrafted mask to look good for a certain base texture set

* the same procedure can be applied for the object placement masks (can it?) - then tiling is more or less solved and object placement remains consistent

* the object placement mask in turn can be passed to the shader so that possible heightmaps/hires overlays can be used dependent on what the area is supposed to represent

* the 8 km size mask can be passed in the (otherwise unused) alpha channel of either base texture or placement mask, so we don't even need a new texture

I think I can come up with the code to do this, I am less certain about my ability to get the artistry (=a good mask to blend textures) right... Stuart, can object placement be evaluated this way at all? Is this something we might want to try?

* Thorsten