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ADE-GP Models?

GHD

GHD

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There are three GP polygons in the GP.bgl. They are stored as two models, one with one polygon and one with two. The unusaul thing is that the model containing two polygons have them both at zero elevation, whereas in the ADE file they are sitting on two different flattens with a 100ft height difference.

If it had compiled both poygons with the same height into one model, I could understand.

Don, can you explain this?

The ADE file is attached to:

http://www.fsdeveloper.com/forum/showthread.php?p=638851#post638851
 
Are you sure they are sitting at two different elevations? One might be floating in the air.
 
As I mentioned a couple of times in other threads, there is no elevation information in a GP poly .bgl. That a poly happens to sit over a flatten at a certain elevation is immaterial. It is up to FS to determine what is ground elevation in the locale of a GP ground poly and that's where it will be displayed.

Maybe Arno can shed further light on the subject.

DOn
 
Wot Don says :) The real issue here is how FS9 and FSX graphics engine decide on the altitude to place the poly.
 
I don't think so.

As it is, if multiple plygons are in a model, they will be displayed at the height under their common reference point.

I think my previous file was in error by having two models. My test file has all of the poly-objects as one model, presumable with the reference point at the ARP.

This means that it is not possible to have poly-lines/polygons other than at the height of the airport:

 
This is all beyond me - I am going back to programming ADE. I need to leave this to those who know what they are talking about.....
 
This means that it is not possible to have poly-lines/polygons other than at the height of the airport
Click to expand...
George, FS9/X decides at what height a ground poly is displayed.

I doubt it is the height of the ARP. The GP .bgl is a separate file and there is no reference in it to the airport. Indeed, ground poly can be placed anywhere, not just at airports. More likely, it is the elevation of a flatten.

Perhaps Arno or Jim or one of the other Guru's can shed some further light on the topic.

Bottom line, (without intending to minimize the effort involved or its utility) ADE_GP is an implementation of FS8 ground polys in ADE - to save users from the trial and error of placing ground polys with GMax. However ground polys created with Gmax in the same "environment" work, that's how they will (should) work with ADE_GP. If you find that's not the case, I can do something about it. But, I can't make them do anything more.

Given that FSX has no inherent ground poly capability, we're fortunate to have what we've got.

Don
 
gadgets said:
George, FS9/X decides at what height a ground poly is displayed.

I doubt it is the height of the ARP. The GP .bgl is a separate file and there is no reference in it to the airport. Indeed, ground poly can be placed anywhere, not just at airports. More likely, it is the elevation of a flatten.
Click to expand...

If it is considered as a model, it will be placed with its reference point at ground height.

If I understand correctly, the GP model has its reference point at the ARP.
 
If I understand correctly, the GP model has its reference point at the ARP.
Click to expand...
Yes, I think that's correct.

And, I also think I see where you are going with this - multi reference points. We certainly don't want one .bgl file per gp object, so that means there would have to be a mechanism to collect objects about a given reference point. That means ADE. Or, perhaps manual selection.

I don't know how Jon feels about that, but for ADE_GP, while I'm happy to address it, I would strongly suggest its a feature for "Version 2" - as I'm sure there will be other enhancements requested. For my part, I'd like to get the basics working and released first.

Don
 
If I understand correctly, the GP model has its reference point at the ARP
Click to expand...

How George?

If it is a model then it is placed like a library object. To place a library object you either have to set an explicit altitude AMSL or you set IsAGL. IsAGL with a setting of 0 (the default) will place the object at the Ground Altitude that is determined by its reference point.

There is no altitude information in the Bgl file that is created. Therefore FS can know nothing about that altitude. So I might surmise that the poly will be placed using 'IsAGL' with 0. On this basis the poly would get placed at the altitude found beneath it.
All models to my understanding have a reference point. For models create in GMax etc the reference point is determined by the designer - They are not always in the middle of the objects footprint. So wherever the reference point of a poly or line happens to be when placed the ground level at that point is taken to be the altitude the poly gets placed at.

Now as I understand it the GP Layer matters and each layer number must have some minor vertical (altitude) factor over and above the lowest (which I surmise is at ground level)

I know absolutely nothing about this and these are FS8 objects that are clearly not the same sort of model as FS9 or FSX ones. What I do understand is that only objects that are associated with an airport can inherit the ARP value. Since these include aprons, taxiways and so on I would agree that any poly placed on one of these ought to take the ARP as its vertical placement reference.

Anything off those parts of the airport that are locked to the ARP are not so constrained. Thus they will take on the altitude of whatever the ground is under them. Since we generally place a flatten under the airport so that everything in the airport space is flat (well not in FSX of course) then it is reasonable to assume that the polys will take the ARP reference altitide - but only because the flatten is set to match.

Off the airport background is anyones guess.

So I agree that most of the GP objects that y'all are trying to place should be at ARP altitude but not because of anything inherent in the model or Bgl file.

Finally of course the FSX round earth model may well affect the altitude the GP Objects get.
 
Don

I agree only for the reasons in my post above. I also cannot see why this should get so much more complex that placing these things created from GMax. If my ramblings are anything like correct then we already have a way to set altitude for these GP Objects - flattens.

Also I would ask which ARP these polys are going to take if they are placed equidistant between three or four airports.

If MCX can convert the objects from the Bgl files you are creating into FS9 or FSX models then of course we could place them at any altitude we like. However that kind of defeats the point of using ADE to place them and you would be as well off to use GMax

Oh and you can have only one reference point per airport so I am not sure where multiple ARPs would come from unless you build overlay airports
 
Jon, I hope this doesn't "muddy the waters".

While the ADE .bgl file does not contain any explict elevation information or an explicit refrence to the ARP, all GP objects in the file are referenced to a single point. It doesn't matter to FS what this point is. It could be to a tree or a remote scenery object. In the case of ADE_GP, its the ARP.

In an FS8-GP .asm.file, every vertex is specified as an offset from that reference point and, as George has pointed out, it is the elevation of the reference point, not the ground elevation at the vertex that governs at what elevation the vertex is displayed. Consequently, because all GP objects are in the same file, they are all displayed at a single elevation.

So, the logical extension is to allow for multiple GP .asm files and collect GP objects for compilation based on the elevation at which they are to be displayed. Then, instead of passing the location of the ARP as the reference point, pass a lat/lon where the ground elevation is at the desired altitude.

Of course, this begs the question "What will be the selection mechanism?". There are several obvious alternatives. But, right now, I'd rather not worry about them. Instead, I'd like to finish this beta, get the base capability released (which will satisfy the majority of requirements) and then focus on enhancements.

I've got to make a trip to the dentist now (lucky me!). So I'll be off-line for a bit.

Don
 
OK - my rantings are off :o. It is me who is muddying the waters based on my lack of knowedge.

If all objects are based on a single reference point and that reference point is the Airport Reference Point then I agree completely that all GP objects will be at the ARP altitude. My deep ignorance of what is actually going on is cruelly exposed :o:o:o

My only defense is that I failed to comprehend that all objects in the ADE GP Bgl file are referenced to the ARP.


So I now agree with the conclusion :)

I also agree that we should not be trying to create multiple reference points for this version.
 
Hi,

Am I missing something?

For the time being we deal with one or several gp polys assembled into normally one mdl and compiled as one gp.bgl. They all sit at the level of the altitude of the ARP.
If we want to place it at a different layer, we would be placing the entire model i.e. all the polys at a different layer unless we manage to change the layer (I do not know how yet but will find out). But would not that lead once again to the quirks (for lack of a better word) to the ones that George showed in one of his screenshots where two models at different layers were involved?
Suppose there is an easy way to make (if wanted) various models inside one gp bgl, we could use the MCX ground polygon wizard to change the altitude of the model with respect to the point of origin c.q. ARP.
Where does my reasoning go wrong I wonder?
We could also forego in that case the use of MCX if ADE would have a means to either change xyz coords of the mdl or lend it some coordinate information (based on the ARP coords) that can be changed.
I hope you can follow me?
 
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Theoretically you could create more than one GP file right now, if you really wanted to, to experiment with this (no need for further complications in ADE version 2 if it doesn't work).

1. Create an ad3 file with a selection of GP objects that should all be at the same elevation.

2. Compile this airport. You will get an ADE file and a _GP file.

3. "Save As" this ad3 file with a new name, and delete (or move) the existing GP objects and create new ones (if desired) at a different location that should all be at a *different elevation* than the ones in step 1.

4. Compile this copy into the same folder as in step 2, with a slightly different name (add 2 to the filename or something similar). You will get an ADE file and a _GP file.

5. Delete the ADE file created in step 4 (but not the _GP file).

Now you have two _GP files for the same airport.

Hope this helps,
 
gadgets said:
And, I also think I see where you are going with this - multi reference points.
Click to expand...

No Don, you read me wrong :o

All I was trying to do was to show that polys will all be placed at the ground elevation of the airport reference point ;)

You pre-empted me, I have just prepared a couple of screenshots showing that the models are definitely defined relative to the ARP.

This is how they are defined in ADE:



And this is the model in MCX:



The problem with this thread is that you write in Canadian English, Jon writes in American English and I write in Geordie English :D
 
On that basis we should expect Roby to provide the best explanation ;)

However the Geordie English was good enogh to explain what is actually going on....
 
tgibson said:
Theoretically you could create more than one GP file right now, if you really wanted to, to experiment with this (no need for further complications in ADE version 2 if it doesn't work).
Click to expand...

No Tom, it's a bit more complicated than that. One would need to create a new airport with a different ARP to allow polys at different elevation. This means having a separate entry in the FSX scenery library.

As I said, I don't want polys at different elevations, all I was attempting to do was show why Roby was having problems with his multi-level airport.
 
Good catch, George. I wondered why the grid was offset from the models, and now I know why. I guess my multiple GP file idea will have no effect, then. You would indeed have to create overlay airports with their ARP's at different locations to get GP objects at different elevations.

That said, you *can* move the ARP in ADE and that will move the reference point of the GP objects (I just tried it). Perhaps this will allow you to specify the point at the airport that will be used to determine elevations?

Hope this helps,
 
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