DF-21 Forums

[lucius]

Background
As you may have read I've been working on getting the portal system to cull and clip geometry (and other portals) correctly to handle complex tesselations and "impossible" geometry in DF robustly (for example see Perplexion). This type of geometry is used everywhere (although its usually subtle) so it must work for any number of portals. This wasn't being handled properly before, which is why you'd have geometry rendering glitches in various levels.

Anyway, my initial attempt at this was to do the portal clipping on the GPU using the zbuffer and stencil buffer. While this did work for the most part there were a few problems. Once problem is when portals were clipped by the near plane - this one is very problematic to fix in all cases robustly. The second problem was actually performance, not GPU performance ( no problem there:) ) or even CPU performance but CPU->Driver->GPU performance due to the excessive number of state changes that were required. The problem here is that it's not really possible to optimize this case very much (other then just having a faster CPU). So I redid the entire system in a completely different direction - which is almost complete.

The new system
The new system employs software portal clipping. Basically you start with the sector the camera is in (if there is one) with the fullscreen frustum. Any visible portals (those facing toward the camera and partially intersecting the frustum) are then clipped to the frustum. It then generates frustums for each of those clipped portals and precedes recursively through the new frustums. As its going it stores a list of sectors visible, along with the frustums and portal polygons through which they are visible.

Finally at render time the list is walked through sequentially (its automatically ordered correctly) from back to front. For each visible sector/portal pair it renders the clipped geometry (including objects) and then renders the portal into the zbuffer (with transparent/translucent texture if there is one - like handrails for example). The reason this is done is so that when the parent sector is rendered, it does not overwrite the contents of the child (think of two overlapping sectors where one is partially visible through a portal).

The next build
The next build should render all the sector geometry correctly in every level... So I will allow every Dark Forces level to be played through a command line that will unlock them all. The INF may not be complete and certainly some logics will be missing - but it should all render correctly. In addition I'll have people test the mods - including complex mods like DT1 - DT4 - and make sure that everything renders correctly. As I've mentioned before objects will be sorted properly so no more dark edges. In addition this system allows for much simpler tessellations - so complex sectors that failed before will now work correctly.

The future
For the next set of builds I will be completing each additional feature group (such as INF, logics, etc.), until every level is playable. For various reasons I will no longer be working on features a level at a time and have switched to a more "wholistic" approach.

Portal clipping screenshots
Here are some screenshots of the portal clipping in action:







As usual any comments are welcome.

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DarkXL....http://darkxl.wordpress.com

[Gez]

I don't know enough about the technical points to make non-inane comments but since the forum isn't very active I'll post just to say I'm following this project with interest and it's nice to see it making progress.

Now for inane comments.
You mention "impossible" geometry... Is it possible to have recursive portals, and if so what happens? For example, taking a simple room with two windows, A and B...

[lucius]

Just to hammer the point home, here are some screenshots of perplexion which shows why this system is needed and what you can do with it. Note this level is one of the Showcase levels for DF, although the portal actually HOMs when not close enough in vanilla DF but here it is always clear (no HOMing). Every adjoin may be like this, it can't be limited to a small set (like newer games) because of the way its used in some DF levels.







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DarkXL....http://darkxl.wordpress.com

[lucius]

[Tsophika]

Long ago I exported JABSHIP to work on in Radiant. I know this overlapping is used in at least one place, a spiral staircase that leads to a level change.

[lucius]

[lucius]

A couple more cool Perplexion screenshots.




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DarkXL....http://darkxl.wordpress.com

[Burning Gundam]

You know, I was thinking to myself this morning "I haven't heard anything on DarkXL at all this week" and then I check the threads and a bounty of information has come about.

This is VERY good news, can't wait to check out the next build

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I don't think outside the box... I customize it.

[sheepandshepherd]

Well, I'm certainly perplexed

[Ryuichi91]

Amazing.. just simply amazing (Why can't Blood get this kind of awesome treatment. Sorry I know its off topic) Lucius by the next build will we be able to play any user made level (even though most of them won't work atm it's released)?

[lucius]

[sheepandshepherd]

Speaking of missing logic . . . will all the original DF levels be beatable, or will there be keys or mission objects that aren't yet implemented? Also, are you planning on implementing all the weapons this upcoming build?

[lucius]

[Emon]

This is fantastic. If I understand it correctly, what you're doing is similar to what Jedi Knight does. Except yours is probably more efficient... JK is known to get exceedingly slow with hundreds of adjoins in view (on modern hardware and a patch that increases the visible adjoin limit)... as I recall, the engine walked extra nodes that weren't necessary.

Overlapping sectors are awesome. You can do so many cool things that are just becoming popular in newer games.

[GreggD]

Holy cow, if I can play the whole game like this before Thanksgiving...That would be nice...

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"If they were created by man, then we can solve them by man." -Tim Sabien

[sheepandshepherd]

[lucius]

Here are lots of random screenshots from various unreleased levels in the game. Note that all the levels are currently working and every sector can now be tessellated (including sectors with overlapping vertices). There are some issues to be fixed and optimizations to be done - but the build should be done soon and you can see the levels for yourselves.

***WARNING: Lots of screenshots***

































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DarkXL....http://darkxl.wordpress.com

[sheepandshepherd]

Nice . . . I can't wait
I'm really not used to being able to see all the textures so clear from so far away, that's pretty awesome.
Is it just my imagination or is the sky BM in the Imperial City screenshot a little stretched? If it is, I'll report it in Codeplex for the future builds. I just wasn't 100% sure, I haven't played the level in a while.

[Burning Gundam]

WOAH!! Awesome looking stuff.

I've never seen Gromas look so vivid in color, I'm really excited now.

Oh, by the way. How do you load mods in the new build? I can't find the area to put the command line in anywhere. Or maybe it's somewhere obvious and I'm just blind. I wanted to possibly get some screenies in on my projects.

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I don't think outside the box... I customize it.

[sheepandshepherd]

Ehh, I think Gromas looks vivid because the red fog isn't implemented.
Load the level the same way you did in DF . . . make a BAT file, type DarkXL.exe -u_____.gob, and run it. Unfortunately, until the next build comes out, you can only play custom levels that replace Secbase-Testbase levels. Good luck getting past the crippling sector bug though lol

[BlazingPhoenix]

Awesome! I definitely can't wait for this build.

[lucius]

[C. Zoui]

Wow. I can't appreciate on a technical level what I am seeing here, but I do know that I like what I see. *thumbs up*

[Marley]

Beautiful

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*ZaP*

[GreggD]

[Taton]

Its funny looking at the second to last screen shot. An amateur level maker will turn bright red from a single improperly stitched texture, but the original game is full of more texturing errors than you can shake a stick at.

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"A fight should be clean and elegant, without waste"
-Asuka Langley Sohryu, Evangelion

[Weregoose]

Holy cow, it's even worse on the other side:



Not being even an amateur level maker, I probably never would've noticed.

Did they use this thing as a palette?

[Magic_Al]

Coincidentally, the second-to-last screenshot in this batch is almost identical to the second-to-last screenshot in the batch released today by the Dark Forces Mod. http://www.lucasforums.com/showthread.php_t=193270

Back on-topic, I'm really looking forward to the next build!

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----- MagicAl`s DARK FORCES Niche -----
http://homepage.mac.com/anewmanagn/magic_al/

Armed only with a blaster pistol and an intimate knowledge of
Imperial methods, MagicAl prepares to go to lunch....

[lucius]

[Burning Gundam]

Haven't tried yet, I haven't done too much work since the asking it to merit doing so yet. But when I have a couple of areas built that look okay to me, I'll give it a go.

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I don't think outside the box... I customize it.