The Compositor

[Necolatis]

Experimented with the ALS compositor in 2019.2.0. The Viggen in these pics have shadows and occlusion map and normal map. Note that I did not fix the afterburner flame or canopy glass.
The red cones are spot-light light bounds, I did not manage to get them to illuminate the runway.
The G91 has some geometry perpendicular to the camera on its back, thats why there is an extra shadow there.

[wlbragg]

The Viggen in these pics have shadows

Wow!
How does that work?
That is really something, what is stopping us from using this in earnest?
Would you be willing to write up a short example and how to implement this?

[Necolatis]

Well its not released yet, and I think tons of effects/shaders have to be ported first.
An example, yes, but it wont be short, lol. Took me hours to figure out some of this, should cover everything you need that is not mentioned in Icecode GL's readme:

First compile 2091.2.0 with COMPOSITOR cmake flag enabled.
Then extract and overwrite in $FGDATA with the zip file from FG Discord.
Edit Compositor/default.xml to say: <PropertyList include="ALS/als.xml"/>
Edit Compositor/ALS/als.xml and comment out the first quad.
Edit Compositor/ALS/als.xml and change the second quad's buffer to color.
Edit Compositor/ALS/als.xml and change the geometry of second quad to cover entire screen.
Edit Compositor/ALS/als.xml and change the properties in sun-shadowmap-atlas to say /sim/rendering/als/shadows/atlas-size
Edit your fuselage effect to add <scheme>als-lighting</scheme> in the ALS technique
Add this uniform to the same technique:

Code: Select all

            <uniform>
              <name>shadow_tex</name>
              <type>sampler-2d</type>
              <value type="int">10</value>
            </uniform>

Add to same technique these shaders, and edit their numbering accordingly:

Code: Select all

<vertex-shader n="0">Compositor/Shaders/shadow-util.vert</vertex-shader>
<fragment-shader n="0">Compositor/Shaders/shadow-util.frag</fragment-shader>

Edit the ALS model fragment shader you use in same technique and add this in declarations: float getShadowing();
In same technique multiply specular and diffuse color terms with getShadowing().
Edit the ALS model vertex shader you use in same technique and add this in declarations: void setupShadows(vec4 eyeSpacePos);
Add this to bottom of same shader: setupShadows(gl_ModelViewMatrix * gl_Vertex);
Move all your local aircraft fuselage effect into Compositor (including what they inherit from), so they have same path just with compositor prepended. For example $FGDATA/Compositor/JA37/Models/Effect/fuselage/myEffect.eff
That step is so you dont have to edit hundreds of model effect paths. As in 2019.2 effects inside aircraft is no longer supported.
Start Fg with:
--prop:bool:/sim/rendering/als/shadows/enabled=true
--prop:int:/sim/rendering/als/shadows/atlas-size=2048
Make sure to run with ALS and enough model shader setting to run your desired technique.

Hope I didn't forget something.
If you want occlusion-map also you will have to implement that yourself in the shader/effect code and bake a map.

[Necolatis]

Also note that the old effect "noshadow" still is respected by compositor, so use that for geometry you don't want to cast shadow.

[Icecode GL]

Very cool screenshots! It's very nice to finally see shadows in ALS on someone else's FlightGear.

The red cones are spot-light light bounds, I did not manage to get them to illuminate the runway.

Spot lights aren't supported yet for clustered shading, i.e. they are registered and parsed but aren't processed as lights. Point lights are, but I don't remember what's their current status regarding shaders.

That is really something, what is stopping us from using this in earnest?

Nothing! As Necolatis said, it's mostly tedious work to port all effects to the Compositor.

An example, yes, but it wont be short, lol. Took me hours to figure out some of this, should cover everything you need that is not mentioned in Icecode GL's readme:

I guess I left my WIP in a worse state than I imagined. Feel free to distribute your own zip with the changes if you want.

Also note that the old effect "noshadow" still is respected by compositor, so use that for geometry you don't want to cast shadow.

It is for now. I've thought of other (more flexible) ways to allow users to select which scene objects they want casting shadows. Nothing is set in stone yet, so if any aircraft devs are planning to add support for shadows/lights, please wait a bit more until this kind of stuff is decided.

[Alant]

Congratulations.

Lesser mortals (e.g. Alan) are awaiting a cook book giving us some clues as how we can use this.

Thanks

Alan

[wlbragg]

Yes, thank you for what you already posted. I think it is a good enough to get me to at least try it.