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not_sure

Make custom transparent textures

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Hey everyone, so I'm trying to make a skybox with transparent clouds in the foreground. Problem is that when I try to make a PNG with transparency DOOM craps the bed.

 

Not too surprising, given the game's age.

 

I'm guessing that I need to use a color that's designated as the alpha, correct?

 

Or do I need to make it a specific file type?

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Transparency

Transparency in a PNG image is achieved through the alpha channel for 32-bit PNG or through alpha levels for palette indices (specified in a tRNS chunk) in an 8-bit paletted PNG. Cyan is not transparent! Cyan pixels in a PNG will be interpreted as cyan color by ZDoom and matched to the closest color (in the default Doom palette, the closest color will be light gray). MS Paint is the only commonly-used graphic software that is unable to manage transparency, if you use it to edit images you have to use another tool, such as IrfanView or GIMP, to add the alpha channel. When saving a PNG image as 8-bit paletted, IrfanView allows you to click on a pixel to mark its color as being transparent.

https://zdoom.org/wiki/PNG

 

Hope this helps.

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PNGs are only supported by some source ports, but don't expect the original Doom (or "vanilla Doom" as it's often called) to support it, after all the PNG standard was born in October 1996, nearly three years after Doom's first release.

 

When you say skybox, do you mean an actual box area within the map used to create the sky? Only ZDoom-based ports and Eternity support that, and both can handle PNGs, so you shouldn't have to convert the image.

 

Alternatively, there's the Hexen doublesky feature where the sky is made of two layers of textures, and the foreground sky texture uses color 0 for transparency. But then you need a port that handles Hexen features in Doom maps, so again, a ZDoom-derivative.

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Yeah, I was thinking there may be a color designated as the alpha channel because that's how Build 3d (Duke 3d) handles it.

 

And I know Doom is older than png, that's why I was asking if there was a different format.

 

I am using Hexen / ZDoom. Sorry, should have mentioned that earlier.

 

And I was doing a ZDoom skybox to experiment with. I was thinking of making a curved dome with a Hexen duel layer sky and making poly clouds that rotate around the view point.

 

Anyway, I just can't figure out how to make a texture with transparencies.

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That bit from the ZDoom Wiki I quoted says that IrfanView allows you to pick a specific color to act as the transparent color, so you might want to pick a strange and outlandish color like pink that you'd never use as your transparent color, that way you don't accidentally "poke holes" in your texture.

I don't know from personal experience how IrfanView and GIMP work with transparent colors (despite the fact that I have GIMP), so that's pretty much the limit of my knowledge on the matter.

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Yeah, I did the files on GIMP. But then when I tried to start the level I got this:

 

error.png

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What a strange error. It looks like it's treating the image file as a text file. All I can think of is to make sure it's actually an image file in SLADE, which it looks like it is, so I have no idea what's going on here.

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Hmm...

 

Well thank you for all your help.

 

Maybe, I'll just try starting a new map.

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No reason to do that. It functioned properly beforehand, didn't it? Just scrap the textures and keep the map. From what I could see in the shot, it looks solid.

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Is the image actually named texturescom_skies0382_3_alphamasked_s.png?

 

It should be put in a textures/ directory. The problem apparently is that it has a name starting with "textures" and is placed in the root directory, causing it to be read as if it were a TEXTURES lump. Put it in a subdirectory to place it in the proper namespace so that this doesn't happen.

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