ALS mode shadow glitch

[wlbragg]

This may be a know problem but it is the first time I noticed it.
Superbuild-next git pull from a couple weeks ago.

[Johan G]

Strange.

I assume that you are not using Rembrandt, but that the shadow is an animated model object and/or a texture. I do not see how ALS could change the animation like that. I guess you could pause and toggle ALS and see what happens.

[Philosopher]

Yeah, it's just related to the simple shadow textures/animations that have been used after the migration from PLIB to OSG, so it's not new at all. AFAIK little can be done about it, and if there was something, it would require changing almost every aircraft...

[wlbragg]

I didn't mean to tie it to the ALS system other than the fact that it is not Rembrant shadows.

[wlbragg]

OK, I obviously don't understand lots of the technical details about how FG renders its elements to the screen. With that said, I dug a little deeper and noticed that I got that shadow when the AI was an actual working airplane model vs an AI model. I had changed it to an AI model after I realized the plane had no spinning prop.and when I checked it again there was no shadow. So that explains a few things to me anyway.
I take it the shadows cast on the ground are handled by the planes xml both in ALS and Rembrant modes?
I assume one could add the shadow effect to an AI model if they so desired?
What exactly is causing the shadow to be viewed at a different altitude based on the viewers altitude?

[Thorsten]

I take it the shadows cast on the ground are handled by the planes xml both in ALS and Rembrant modes?

They're actually really different.

ALS does not draw any 'real' shadow of an airplane (or any other scene element) - every shadow you see in ALS is an illusion of some sort. Rembrandt has a genuine camera pass in which objects are rendered from the perspective of the light source, creating a so-called shadow map, which is then used in a second pass rendered from the position of the eye to determine what is in shadow and what is not - Rembrandt does pretty much what nature does, it follows rays of light to determine shadows (except many objects are exempt from the shadow camera pass so they don't cast shadows in Rembrandt - clouds and trees for instance). Which is to say, all shadows in Rembrandt are guaranteed to be on the ground and properly projected.

The 'shadow' of some airplanes in ALS is a fake, it's a second model attached to the airplane and animated in such a way as to mimic a shadow - technically for ALS it is treated and rendered as part of the airplane, ALS has no way of knowing that it's supposed to be a shadow or where it should be, it would not disappear in overcast skies and... well... it can detach from the ground if the animation isn't done properly.

This is an airplane-model side problem.