Creating a custom sky texture

[Gustavo]

Hi all,

 

Wanted to see if there's an official guide on how to create a custom sky in Doom2? I tried to basically select the 256x128 area of an image, changed the name of the image to RSKY1, put the image inside a wad between PP_START and PP_END markers and then converted the image to a Doom graphic (in Slade 3). One of the things that happens after this stage is that the image's palette gets destroyed and when I play the wad the sky looks completely messed up. I have not found any guidelines on how to make the image's palette approximate Doom's palette. Any guidance would be appreciated. This is a map for PrBoom.

 

[ReX]

As you've discovered, an image needs to be in the DooM color palette in order to be rendered properly in vanilla DooM and some source ports. The other limitation is on the image format (DooM Graphic Format). One way to do what you're asking is to start with one of the DooM skies in 8-bit bitmap, using (say) MS Paint. (You'll need to export the sky image into such a format; I can't be sure, but SLADE might be able to do this.) Then, you'll need to copy and paste your custom sky into the DooM sky image. If the palette's are similar, you could get a custom sky that is acceptable in-game.

 

All of this requires the use of old MS software, such us Win 95 or Win XP (or an emulator), as newer versions of MS Windows don't seem to support the editing of 8-bit BMPs.

 

To recap, try this:

1. Use an older machine to export any DooM sky into 8-bit BMP format.

2. Open MS Paint in your older machine & open the DooM sky BMP image.

3. Copy and paste your custom sky onto the DooM sky BMP mage.

4. Save

 

If you don't have older versions of MS Win and MS Paint send me the image and I'll use one of my older computers to convert the image.

[ReX]

2 hours ago, Gustavo said:

I tried to basically select the 256x128 area of an image ....

Also, if you simply cut and paste from an existing image, you'll likely have a problem tiling the image so that it properly wraps around the horizon. Note how the left edge of a DooM sky fits exactly up against the right edge. This allows the image to "tile" horizontally with no visible seam. In other words, you'll probably need to make your custom sky tile before it looks realistic in-game.

[Gustavo]

Thanks! I'll try this out.

[Tango]

would you be able to post the unconverted sky image? usually if you do the conversion to doom format in slade, it'll try to match colors to the doom palette as best as possible, but some images might just have colors way outside what doom's vanilla palette contains, unfortunately :(

[Kappes Buur]

A sky can be made in different sizes to cover the horizon 

 

DOOM2 uses one texture of size 256x128 to cover 90 deg of the horizon ( so it is repeated 4 times, once for each cardinal direction ).

If your sky image is 256x128 and tiled properly and using the DOOM palette, then the simplest method of using your own sky image is to just name the sky image in your pwad the same as the sky image in the IWAD. This will then overwrite the original sky image.

 

 

But, if you are more adventurous, you could just as well use

one texture of size 512x128 to cover 180 deg of the horizon ( so it is repeated 2 times)

or

one texture of size 1024x128 to cover 360 deg of the horizon

or

4 different texture of 256x128 to cover 90 deg of the horizon each

In each of those cases you have to update the sky in TEXTURE1

 

for example

 

 

Edited September 21, 2019 by Kappes Buur