The Compositor

[Algernon]

I've just started playing with the compositor and it's fun so far. I also need to figure out an appropriate way of preventing light spilling out through the aircraft's geometry - the first application I'm attempting is cockpit floods. With Rembrandt, you could keep the light volume within the bounds of a mesh to do this (in this example, the cockpit tub was used to form a separate mesh of its internal space to act as a Rembrandt volume object), but that's not going to work here.

Also, are Compositor's lights able to - or planned to be able to - be dimmed dynamically with a property?

[icecode]

With Rembrandt, you could keep the light volume within the bounds of a mesh to do this

I'm not sure what you mean exactly, but with the Compositor there is a range-m property that changes the radius of the sphere volume in the case of pointlights and the range in the case of spotlights. I think that should be enough to keep cockpit lights in check.

Also, are Compositor's lights able to - or planned to be able to - be dimmed dynamically with a property?

Yes, it's planned. Although I'm still trying to figure out how to do this in the most flexible/easiest way possible. Unfortunately it's not too high on the priority list at the moment - clustered shading wasn't even applied to every effect yet, so it'll only work on models with model-default. I'll be dealing with that first.

[Algernon]

That's cool Just working very far ahead in my planning, but I too have other things considerably higher on the priority list.

[jsb]

Hi,
regarding http://wiki.flightgear.org/Compositor#N ... developers
sorry, if this question was already answered, but where do I have to put the light definition in an aircraft?

I work on the CRJ700 which has rembrand lights. A closer look at the .ac and XML files (included in the model) show
1) a 3D sphere or cone with a light animation (very similar to the light definition described in the wiki article mentioned above)
2) a plane holding a texture ("lightbulb" you look at) and billboard animation.

I found I have to keep the plane with the texture otherwise I cannot see the "lightbulb" anymore. The sphere I had to remove because it became solid black when I converted the light <animation> to a <light>

So, is the model XML the right place for <light>? Maybe you can point me to a working example?
Thanks

[icecode]

Yeah, you should place <light> in the model XML. However, unlike in Rembrandt, you don't need a light volume in the model itself (a sphere or cone). The <light> itself is the only thing needed.

[jsb]

Ok, I will try this. But I should keep the "2D" textured plane (billboard) to have a "lightbulb" to look at?

Edit 1:
I can see the debug cones and spheres now but I do not see any light on the ground (nav light, taxi, strobe...)
Q: is it possible to use use properties in the light e.g. to set r,g,b on the fly or change direction of a spot light?

[icecode]

But I should keep the "2D" textured plane (billboard) to have a "lightbulb" to look at?

Yeah, you should keep the billboard. The <light> only provides lighting to surfaces.

I can see the debug cones and spheres now but I do not see any light on the ground (nav light, taxi, strobe...)

This hasn't been implemented yet, it's only working on models with model-default for testing purposes.

[jsb]

Naive question: what has to be done to implement it? How much work will it be and what knowledge would be required?

[icecode]

It's mostly copy-paste work and deciding on a good strategy so people have enough freedom to choose if they want clustered shading or not. Don't worry about it, I'll probably be pushing some changes regarding this in the following weeks, I've just been quite busy for the past month or so.

[jsb]

Would it be possible to do a quick hack to have a "ground element" (e.g. runway, apron) reflect the light so I can adjust the landing light spots?
I also noted, that the stobe lights light the interior (cockpit) so obviously the skin of the aircraft does not block light - not sure what I did wrong or if this is supposed to work.
I worked around this with a select animation that uses view-internal flag to hide the light

[icecode]

Would it be possible to do a quick hack to have a "ground element" (e.g. runway, apron) reflect the light so I can adjust the landing light spots?

Unfortunately it's not trivial to add support for clustered shading in other Effects. If you are familiar with Effects and Shaders you can try having a look at model-default and see how it's implemented there.

I also noted, that the stobe lights light the interior (cockpit) so obviously the skin of the aircraft does not block light - not sure what I did wrong or if this is supposed to work.

Yeah, that's normal. "Fixing" it would require shadow mapping support for any light (not only the Sun), which is prohibitely expensive for now.

I worked around this with a select animation that uses view-internal flag to hide the light

That's a good workaround. I'll also try adding a parameter to effects that let the developer choose if they want the surface to be affected by lights or not.

[jsb]

That's a good workaround. I'll also try adding a parameter to effects that let the developer choose if they want the surface to be affected by lights or not.

Unfortunately I have minimal knowledge about effects and shaders. Thinking about the cockpit it would be nice to have lights there too e.g. at night. Maybe it is possible to have parameters that allow to group lights (e.g. exterior, cabin, cockpit, ...) and have the groupnumber assigned to surfaces/materials so a stobe light would light only fuselage and a cockpit light would only light panel elements?

[abassign]

Hi, I have a problem with the compositor (the version of FGFS is 2020.3.0). In both the 2020.3.0 and the 2020.2 versions, I noticed that the transparent surfaces have an anomalous behavior as a function of the angle of incidence of the light. This problem is also evident for the canopy.
As you can see from the images, the beacon (the intermittent light placed on the upper back of the fuselage), is created by a dark red colored hemispherical surface, this surface becomes transparent in 80% of the possible view directions. This anomaly is also present for the transparent part of the canopy. Obviously the surfaces have been configured with the effect:
<Inherits-from> Effects / model-transparent </ inherits-from>
Anyone have an idea how to fix it?

Regards, Adriano

[icecode]

I'm sorry but I don't understand what the problem seems to be. Is the issue reproducible on a publicly available aircraft so I can test for myself?

[wkitty42]

my understanding is the red light dome lens becomes transparent when it should not... the first picture shows the red lens properly... the second one shows the red lens is transparent and you can see the light's internals.. the red lens should be a red lens all the time...