~-Translucent Line Bug-~ (bug??)

Thu Oct 16, 2003 1:33 am

When you use the translucent line special with a texture, it causes the entire texture to be drawn, regardless of sector height. This is on a double sided line (duh, why else would you want a trans line??).

Its OK if the texture is the same hieght as the texture, but if you only want part of the texture seen, it ends up drawing the whole darn thing, producing undesirable results.


Dunno if this is a bug or not, but i dont like it.

Thu Oct 16, 2003 1:36 am

oh, and it also causes textures to not be repeated (if you use too small of a texture)

Thu Oct 16, 2003 1:40 am

immortal18 wrote:oh, and it also causes textures to not be repeated (if you use too small of a texture)



That has always been the case with mid-textures on 2-sides lines and is ok. In fact, changing this wil break a lot (maybe most?) maps ever created. I'm not sure about your first one but I don't thing Doom ever clipped those textures to the open part between the sectors. I'm certain it doesn't have to do anything with translucency.

Thu Oct 16, 2003 2:37 am

oh..... i feel stupid now. :(

(ive been editing maps for a long time now....)

but still.... i dont like having to make my own texture just to make something transparent. but... i guess thats my own problem, since nobody else has said anything.

Thu Oct 16, 2003 3:44 am

There is an editing fix for this problem which has existed (as Graf Zahl said) since there was only doom.exe.

Instead of making your line with the see through/translucent texture on it simply cut across the middle of a sector, or make it the line between 2 identical sectors - make it the line between 2 sectors with slightly different light values. A difference of 1 is enough. You'll never see that difference as a player (I'm not even sure that (Z)Doom can render that difference) but it is enough so that the line gets clipped at the floor/celing.

Something like this:

Code:
________________________
|                      |
|                      |
|       Sector 1       |
|      Light 128       |
|                      |
|______________________|
|                      |
|                      |
|       Sector 2       |
|      Light 129       |
|                      |
|______________________|


I have seen someone (Cyb?) explain why this happens, but I forget the details. Anyway, that's the fix. :)

Thu Oct 16, 2003 3:59 am

Biiiiiiiig help! Thanks!

(its amazing how one person can make a world of difference for another!)

BTW, it sounds like the "fix" you describe was intentional since doom was first coded...

Thu Oct 16, 2003 4:24 am

From memory, it wasn't so much the fix that was intentional, but the "bug". Something to do with doom treating all areas as effectively the same sector/view/something if it looked identical to cut down on visplanes - or something like that. Like I said, I've seen an explanation, I just don't really remember it. :(

Thu Oct 16, 2003 5:57 pm

I could fix this very easily, but as has been pointed out, doing so would break pretty much every map that uses 2-sided midtextures.

Enjay wrote:A difference of 1 is enough. You'll never see that difference as a player (I'm not even sure that (Z)Doom can render that difference)

ZDoom can render the difference, but Doom could not. As you say, though, a player isn't likely to notice the difference, especially with a texture in the way between the two sectors.

Enjay wrote:From memory, it wasn't so much the fix that was intentional, but the "bug".

I think it is a genuine bug. The Doom renderer does not store clipping information between sectors with identical properties, because it sees that no sprites can be clipped by the line. So any midtextures on the line don't get clipped either.

Fri Oct 17, 2003 1:34 am

randy wrote:I could fix this very easily, but as has been pointed out, doing so would break pretty much every map that uses 2-sided midtextures.

Like a fence? Maybe this could be made a linedef flag, but uh... we're getting short on linedef flags.

Fri Oct 17, 2003 1:57 am

Hirogen2 wrote:
randy wrote:I could fix this very easily, but as has been pointed out, doing so would break pretty much every map that uses 2-sided midtextures.

Like a fence? Maybe this could be made a linedef flag, but uh... we're getting short on linedef flags.



There's one left and I can imagine something more useful than this. I have seen so few maps that have problems with this that I doubt there is any need for it.

Fri Oct 17, 2003 3:50 am

Graf Zahl wrote:I have seen so few maps that have problems with this that I doubt there is any need for it.


I doubt there is a need too. I suspect there are very few maps because there are mapping solutions to it - ie make your own texture of the right height, or use the lighting solution I mentioned. By the time a map is released, things like this should have been fixed by the author, so there shouldn't be many maps with the problem. That doesn't mean that mappers haven't been baffled for years as to why it happens. I know I was. :)

I'm not actually saying make the flag. In fact, as I said, I see no need with 2 solutions already available. It would just be nice if the easy solution (the light thing) were a little better known. Then mappers wouldn't be in the situation I was first time I had this problem - of nipping in and out of the editor, trying all sorts of different things to make my texture clip as I wanted, and frustratingly, failing each time. :evil:

Thanks to whoever it was who mentioned on whichever forum it was how to fix it. That's where I found how to sort this problem out.

Fri Oct 17, 2003 7:25 am

Wish I'd known a few years ago about the "light level" fix. I came up with my own fix, which consisted of having a floor height difference of 1 unit between the two sectors. That stopped the fence or window bars from being rendered below the floors, but also required a (unnoticeable) lower sidedef texture.