Re: [Flightgear-devel] FG vs. FSX demo

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

Hi Vivian,

> That's really good to hear  - but if we are falling behind in some  
> respect
> then we will make an effort to improve. I am reminded that the flag and  
> wake shaders are inoperative when Atmospheric Light Scattering is activated.  
> With  the departure of Emilian, I see no prospect of this being fixed unless
> someone else steps up to the plate.

Well, we couldn't possibly leave the flag just hanging around, could we? :-)

http://www.gitorious.org/fg/fgdata/commit/be7ee7e06cf4237d60cf8ae5849cf098308b7cd8

(The flag shader is a simple variant of the default model shader, so just 5 minutes of Copy/Paste the flag-specific code into the default model fragment shader did the trick - that must have been my new record for shader conversion. Also, in ubershader-lightfield.frag we now have all the code blocks of the atmosphere effects nicely separated and lined up in a fragment-only environment, so when you need to write a shader which isn't performance critical, then I recommend just copy-paste of the four blocks, supplying them with properties, and you should be almost there...)

As a suggestion to improve the Vinson, I would ask for some dirt/rust/stains on the Flightdeck - the homogeneous grey appearance is the thing that sticks out most to my eye.



> I recently saw a short video of FSX with moving cars and trucks  
> populating
> the roads. We can do that up to a point, and trains as well, and I  
> forgot to
> mention that we can also texture tracks and roads properly:

> We can only have a few - around 50 if we are to keep framerate within
> bounds. If we ever get the Kent scenery fixed up well enough for release
> I'll include this around Manston/EGMH.


You seem to have managed the trick to align the uvmapping of the street texture with the direction of driving. If so, I think we could have an almost arbitrary number of (low resolution) cars for cheap by shader magic:

* use an overlay texture which is transparent except where the cars are supposed to be
* use the heightmap technique of the urban shader to give them some substance
* overlay them on the lane and move one coordinate along the driving direction over time
(* add light effect in dark and so on)

Since this could all be in the fragment shader, and only a vanishing amount of screen pixels would usually be occupied by linear features such as roads at any given time, you could generate tens of thousands of cars that way without hitting the performance badly.

Of course they'd suffer from the same artefacts as the urban effect from close-up, but the sheer number may completely make up for that.

Cheers,

* Thorsten