Transparent walls for windows and such

Hi!

So I'm looking for instructions to create a transparent wall to create windows indoors you can't shoot through.

I remember seeing a scene in the Requiem Wad, where there was an open area with invisible walls around the enemies. After walking through a gate, the walls lower and the creatures can see the player, and a mighty battle engages!

In another wad, I saw a window with a partially transparent texture, and I thought that that was something I'm after.

Any ideas how to make partially or fully transparent graphics for a Doom2 wad?

Vanilla Doom itself doesn't feature any translucency. Alternatively you can apply one of Doom's many fence textures to a line's "Middle Texture" for that effect. You could also create your own texture that features a "Checkerboard Transparency" in which every other pixel is cyan . It's not all that pretty but it's a decent approach. I've seen one of Essel's screenshots of KDiKDiZD that featured an experimental approach at this and it was really quite good.

If you are mapping in a different format, such as Boom, Linedef action 260 will apply transparency to whatever middle texture the action is applied to.

If you're interested in creating a wall that you can see through but not shoot through, such as the windows in UAC Ultra MAP01, MAP02, and MAP08, there are several different approaches at this. Some involve changing a sector's index, or Boom Transfer heights and stuff. The most simplistic approach I can think of that I've seen in some older wads is creating a sector that isn't attached to any walls, and making the sector ceiling height one unit above the floor, and making sure no upper textures are applied to the sector. It will look stupid in Doombuilder's Visual mode but will render completely invisible in gameplay. Technically you can shoot through the left, right, and bottom cracks of the window with extremely precise aim, and there are definitely more precise and effective approaches at this, but that was the easiest I could think of.

40oz said:

Vanilla Doom itself doesn't feature any translucency. Alternatively you can apply one of Doom's many fence textures to a line's "Middle Texture" for that effect. You could also create your own texture that features a "Checkerboard Transparency" in which every other pixel is cyan . It's not all that pretty but it's a decent approach. I've seen one of Essel's screenshots of KDiKDiZD that featured an experimental approach at this and it was really quite good.

Heh. This only really works if it's for a very limited, controlled setup where the foreground and background are the same color, and are of a similar overall brightness. For anything else, it'd look like exactly what it is: a 1x1 checkerboard cheap trick :P

For glass windows without translucency, something more like the "white diagonal lines" glass midtextures from Eternal Doom would be more useful. But yeah, in a sourceport, just go for translucency. I'd generally recommend sticking to a relatively low opacity, like 10-15%, to make it subtle. There's an odd tendency for people to make really opaque glass in Doom, and it just looks kind of silly.

If you want to accomplish (in vanilla doom) the effect of a wall that you can see through, yet is solid, you must perform some bsp trickery.

Doomworld has a pretty good article on it, but if you're like me (i.e. slow to understand) be prepared to spend several frustrating hours getting it to work the way you want:

http://www.doomworld.com/tutorials/fx5.php

Well, this thread just made me realise I've missed many windows in several wads because translucency was turned off by default in PrBoom+.

I've checked PrBoom 2.02 and translucency is set at 66 there. Is this the setting most people use ?

Weird, prboom+ has always had it on for me. But I never messed around with the values, just left it at 66. A bit too opaque for my taste though, I try not to use transparencies beyond some really specific effects because of that.

Phml said:

Well, this thread just made me realise I've missed many windows in several wads because translucency was turned off by default in PrBoom+.

I've checked PrBoom 2.02 and translucency is set at 66 there. Is this the setting most people use ?

It's the usual default, yeah. Keeping that setting will be most likely to make translucency look as intended. The correct way to set a custom translucency level for a line a Boom map involves the use of something called a tranmap, a precalculated translucency table.

That makes sense. Thanks.

40oz said:

The most simplistic approach I can think of that I've seen in some older wads is creating a sector that isn't attached to any walls,

Even though you mustn't merge inner sector's walls with outer's, you can still place the corner vertices on the walls to seal the area completely. Sound will still pass however.

Note that Hexen supports completely impassable middle walls natively. Still, the breaking glass effect can be achieved with success in Boom as well, such as in the 6fiffy* wad series. It may become more complicated to apply translucency both to the full glass and the broken glass. You'll need room to place all those middle linedefs, and make sure they actually are cut off into the floor or ceiling, when not supposed to be seen.

Phml said:
Well, this thread just made me realise I've missed many windows in several wads because translucency was turned off by default in PrBoom+.

To make the fireball sprites look good, I suppose. See this post to enable translucency without diluting the sprites.

REDUX E2M4 has a niffty example of a window which is shootable, does not break, but shatters.

The correct way to set a custom translucency level for a line a Boom map involves the use of something called a tranmap, a precalculated translucency table.

Slight bump as I've been searching for tranmap and only found lots of technical jargon that is incomprehensible to me. Is there a wad using tranmaps for windows I could look at to get a better idea of what it is I should do ?

The basic idea of a tranmap is that it's a table. You have two colors that you want to meld into one, the front color (of the translucent thing) and the back color (of whatever is behind the translucent thing).

So, you use the front color's palette index as the abscissa of your table, and the back color's palette index as the ordinate, or the reverse. And the entry at these coordinates is the final color that you will use.

As a result, a TRANMAP will appear, graphically, as a raw image making a square of 256x256 paletted pixels. In this thread, Essel posted an example file with many tranmaps in it.

I've seen that post (or at least a close version on Doomworld) and it doesn't seem to be what I'm looking for, or if it is, it is written in a way that I don't get it. Your explanation also falls into "incomprehensible to me". What I'm looking for is a wad with a translucent window using a tranmap to get a specific translucency value.