P3D v4 Legacy BGL / MDL Features Missing in V4

[theisomizer]

Hey folks, here's a pretty broad question. Apologies if this has been answered elsewhere, I usually work more on the programming side of things than content.

What exactly has changed between FSX/P3DV3 and P3DV4 in regards to compatibility with legacy BGL/MDLs? I'm specifically interested in 3D Objects, both scenery placements and simobjects (AI/user aircraft). This would be any differences in rendering compatibility with V4 with either MDL8 (scenery object and aircraft) and MDL9 (scenery object) files, either standalone or embedded into a BGL.

From what I have read online the main complaint seems to be with FS9 AI aircraft (MDL8) not rendering or even causing a CTD. Some say they just have visual glitches, however. I've read yet other threads saying many ASM-based sceneries may be broken, although this also does not appear to be the case. There is also the Randazzo post on Avsim that has already been discussed on here that sent many into a frenzy. Instead of accepting that everything must be V4 compiled as the answer, I would like to know what techniques specifically don't work or are causing issues. For example, is it just certain ASM tweak techniques, or say any static object with a single vertex /index buffer and material completely can't render in the sim?

I can run some of my own experiments on this, but curious if any other developers already have firsthand knowledge of the specifics that they can share. We could compile some of this knowledge into the wiki for the benefit of both end users and all of us maintaining tools that support these formats. I'd also be curious in any other incompatibilities in BGLs or textures/lighting, but for the purpose of my own experiments I'm limiting the scope of this to MLD8/MDL9 (drawn with bgl_fp opcodes) inconsistencies for now.

Thanks in advance for any help!

 

[WarpD]

ASM has been removed from Prepar3D v4. IT's not broken, they removed it entirely. There is talk of a tool being made that will scan MDL and BGL files and tag those that are not v4 SDK compliant so end users can remove them.

 

[=rk=]

We could compile some of this knowledge into the wiki for the benefit of both end users and all of us maintaining tools that support these formats.

Do you mean this wiki
http://www.p3dwiki.com/
or this one
http://www.fsdeveloper.com/wiki/index.php?title=Main_Page

 

[GaryGB]

Hello:

Whereas it appears to have been the assumption among those with P3Dv4 installed that ASM no longer 'works' in P3Dv4:

http://www.fsdeveloper.com/forum/threads/gp-and-custom-ground-lines.440977/page-2#post-780771

Gary, FS2002-style .asm GPs are not used for PV4.

Don

...subsequent to recent tests performed with P3Dv4, it has been reported:

http://www.fsdeveloper.com/forum/threads/gp-and-custom-ground-lines.440977/page-4#post-781162

...it does seem that PV4 will display FS8-style GPs - at least so long as they are placed over aprons and taxiways.

Don

In this context, SCASM / ASM Ground Polygons (aka "G-Polys" / "GP's") are flat non-MDL-based 3D scenery objects that have limited material properties.



PS: AFAIK, one of the major discussions regarding this topic with LM was this thread:

http://www.prepar3d.com/forum/viewtopic.php?t=12857


GaryGB

 

[theisomizer]

I can add to the FSDeveloper Wiki. I'm not sure how much else other folks use it but I still reference it a lot.

So MDL8 (bgl fp opcodes) are gone, this is unfortunate but good to know. Exactly the conversation I was hoping to start. I'm curious about MDL9 now too, as it still uses some bgl opcodes out of the box(namely DrawTriangleList), but many sections are in RIFF. It would be interesting if specific object types or opcodes have been removed due to some of the shader refactoring.

Ground polys work, very interesting. I will look more into that. It seems they have still some logic for BGL opcode parsing in place, but I'm hoping to work on some tooling that can convert the relevant bits.

 

[GaryGB]

http://www.fsdeveloper.com/forum/threads/legacy-bgl-mdl-features-missing-in-v4.441069/#post-781460

I can add to the FSDeveloper Wiki. I'm not sure how much else other folks use it but I still reference it a lot.

So MDL8 (bgl fp opcodes) are gone, this is unfortunate but good to know. Exactly the conversation I was hoping to start. I'm curious about MDL9 now too, as it still uses some bgl opcodes out of the box(namely DrawTriangleList), but many sections are in RIFF. It would be interesting if specific object types or opcodes have been removed due to some of the shader refactoring.

Ground polys work, very interesting. I will look more into that. It seems they have still some logic for BGL opcode parsing in place, but I'm hoping to work on some tooling that can convert the relevant bits.

I don't (yet) have P3Dv4 to test with, but you may also wish to see the interesting conditional display achieved by Arno and Alfredo via SCASM (tested and reported for P3D versions 2.x / 3.x) ...here:

http://www.fsdeveloper.com/forum/threads/mcx-ground-polygon-conditional-display.438060/


Perhaps you might be inclined to test and report whether this also works in P3Dv4 ?

GaryGB