Doom3world

Alright then everyone, here's an attempt to a video tutorial which should be helpful to make a simple level with 2 rooms and one hallway between them and to setup a light and a spawn to make the map 'playable'.

For instructions on how to setup the system so that you can run the editor and compile the map aswell as how to move around and create a brush in the editor will be explained in another tutorial and is already covered pretty good in other tutorials here at this forum.

You will need to have WinRAR and the TSCC codec for this to work, and if you are too dumb to figure out how google works, then I'd say there's 0% chance that you could handle a level editor.

This tutorial kinda expects that you know how to copy/paste stuff inside the editor, and create brushes and move around in the views.

http://www.mnemic.tk/education/videotut ... o_tscc.rar

Size:4.48 Mb
Length:4:06 Minutes

This is the direct link to the video tutorial, if you would like to read some more about it and check out some of my other tutorials just go to my page
over at http://www.mnemic.tk.

update on video and BUMP.

mitre!

ie;

http://www.geneticrose.com/mitre.jpg

(Much as some people may deride it with all these huge poly counts, the basics are important)

Oh, and the codec for those that don't have it;

http://www.techsmith.com/products/studi ... wnload.asp

Please restrict the images in your post to 640 pixels width if you use the [img] tag. Thank you! -Burrito

For structural walls it's best *not* to miter where possible and simply butt corner walls together (like the one you've said is wrong but *without* the overlap) so the inside edges touch.. although having said that, this is the old Quake3 way of doing it for reasons related to quake3 BSP splits/planes, by using a miter on a structural wall you 'potentially' create an extra diagonal BSP split/plane. It's possibly different for Doom3 becasue of the way it now handles VIS(ibility)

The only thing you should really miter by force of habbit is entity based brushwork like func_statics, func_doors, func_explosives etc, they're seen as being 'non-solid' to the game engine (need to double check this asap).

While I agree that using mitre on interior corners could create a diagonal split across the floor, it's unlikely (afaik) to do so.

But having said that, the video tutorial still shows an even worse way of doing it.


And Doom3's vis calculations would (I assume) have no effect on the bsp process since bsp is done prior to vis.

Actually it would have no effect whatsoever, because Doom 3 doesn't use BSP. It uses portal based visibility.

hmm, so what mitre showed wouln't help anything in Doom 3?

Ooooooh, I didn't know that. Ta.

Doom 3 uses portals? I thought he still used BSP trees, where did ya read this?

I kinda have no idea of what a 'portal' is in this case so if ANYONE could write like a short description of one or give some link to one it would be great, I kinda understand how BSP works I think since I know the basics of HINT brushes with Half-Life leveldesign, am I on the right track or am I totally mislead??

I think Doom3 still uses BSP. For example for collision detection or automatic portal calculation.

Basically a portal is the conection between two cells or sectors. A portal could be a door, a window, a crack on the wall, etc. There is special portals like mirrors that link a sector with itself but mirrored.

Now, the way Doom3 makes use of the portals for visibility should be like this.

It calculates the sector where the camera (the player) is in. Then for each portal (in the current sector) inside the viewing frustum (or viewing volume), the camera frustum is clipped against that portal so we end up with a new frustum that will be used to for test visibility for the next sector. That operation will be repeated until there is no more portals inside the frustum.

Because I have a lot of problems explaining myself in english, here you have a series of images explaining the process.

First we have the camera (red dot) in sector S1. In blue you can see the frustum. So we check, for that sector, which portals are inside. In that case we have portal S1->S2 inside the camera frustum.



In the next step we clip the camera frustum against the portal S1->S2 so we end up with the following frustum (purple color).



Now we have portal S2->S3 inside the current frustum so we clip that frustum against the S2->S3 portal. The resulting frustum (green color) is:



So now, if we check for more visible portals, we learn that no more portals are inside the current frustum (S3->S4 portal is outside the frustum so S4 is not visible).

So now, what we do is start rendering things. First we render S3 (leaves inside the frustum) and all models that are inside the frustum (green dots) as you can see (grey dots are discarded models).



Now we back to sector S2 and we do the same thing as with sector S3. Render S2 visible leaves and models inside the frustum:



Finally, we back to sector S1 and do exactly the same thing as with sectors S2 and S3:



So at the end we end up with the following image:



As you can see, we end up rendering visible leaves in S1, S2 and S3 and all objects inside the successive frustums I've shown.

This is how (very) basically a portal rendering engine works. I hope that helps you to clarify something your understanding about portals. I did my best!. Hopefully with the time I could improve my english.

Greets.

hm, im sure for ppl who understands english and are better with this stuff this is all just common sense, right no I'm too tired for that explanation, gonna try once more tomorrow tho, nice review.

I have a question about portals. Does the mapper have to set the portals up himself? In that case, do I just make a block with that texture and stick it in doorways?

Since I don't have Doom3 I can't ensure that, but I think that portals are automatically calculated by the engine through BSP. Ok, maybe there is some special material (portal material?) that could help the engine to place portals but I don't know.

Actually, you HAVE to manually insert Vis portals. You place no vis portals == the engine render your entire map in one time!

Yes.
Visportals give you great control over the vis process.

Use them similar to Quake3's hint brushes, yet now they're more science than art compared to Quake3 vice versa approach

Think in terms of:
Can this visportal see another, if so can the other one see another one?
If not, then you have nice closed volume for visblocking.

Berserker, I just wanted to say you rock for posting that. I happened to know it, but I also know it takes time and energy to put together images and explanations such as yours. Well done.

BTW looks like I may have found my D3 mapping home!

Happy welcome

Thanks!.

I you want an interesting discussion about portals, read this one.

Greetings.

When I try to watch, it tells me it encountered an unknown error.