Transparent PNGs?

Lexus Alyus · Post by **Lexus Alyus** » Sun Mar 28, 2004 10:36 am

Wow, I never knew cyan was so... blue...

HotWax · Post by **HotWax** » Sun Mar 28, 2004 1:18 pm

ellmo wrote:Yeah, I always use default MS-fuckin'-Paint pink colour... by the way, setting the color to be transparent is simple even in Paint. Especially for *.gifs.

..... Umm, at this point, it's customary to explain.

Lexus Alyus wrote:Wow, I never knew cyan was so... blue...

It's 0 red, 255 green, 255 blue.

SargeBaldy · Post by **SargeBaldy** » Wed Mar 31, 2004 11:59 pm

pretty sure you're not supposed to use cyan on PNG images. just use the normal PNG transparency.

Post by **Enjay** » Thu Apr 01, 2004 5:45 am

Lexus Alyus wrote:Cyan? I never knew there waa cyabn colour in doom...

Pretty sure that's the point. There is no cyan in Doom, so you can make an image with cyan in it that a doom graphics tool will use for creating transparent areas in the doom format. If cyan was in the doom palette, then doom tools would not know whether the areas you had marked with cyan were supposed to be visible cyan or converted to transparent areas.

I think the reason cyan has become a standard in many tools is that the earliest ones (eg dmgraph.exe) used it and it kind of became the norm. However, DeePsea uses magenta (by default) and some versions of deutex used a muddy sort of green by default.

Lexus Alyus · Post by **Lexus Alyus** » Thu Apr 01, 2004 6:42 am

Ha, that makes sense now you mention it

The simplest things always surpass me... for some reason...

Cyb · Post by **Cyb** » Thu Apr 01, 2004 12:19 pm

SargeBaldy wrote:pretty sure you're not supposed to use cyan on PNG images. just use the normal PNG transparency.

You can use any palette index actually, convert the image to a 256 color png and then set a color transparent, cyan is a good one to use just because it makes the sprite stand out from the transparency (though if you forget to set it to transparent in the PNG then it'll show up as a light blue in Doom, the closest color the palette has to cyan). PNGs don't even need to be in the doom palette as ZDoom will convert them for you.

This actually allows for maps that work in Doom, Hexen and Heretic (and Strife) if you make all the textures 256 color pngs and do some kind of wacky item/monster placement scripts (if finding out the game type is even possible). It would be more trouble than it's worth, but still kinda neat I think (I've already made one myself with a single sector box and a player1 start and that's it).

Enjay: most wad tools base transparency conversions on a palette index and not the actual color in the bmp I believe. Cyan is often (incorrectly) set as index 247 because none of the graphics in the original doom use that idice, though a few in doom2 do. With most (all?) graphics tools, for example, I'm pretty sure you couldn't make a patch with all 256 colors of the pal in it, though it's perfectly possible.

Post by **Xaser** » Thu Apr 01, 2004 8:28 pm

Enjay wrote:If cyan was in the doom palette, then doom tools would not know whether the areas you had marked with cyan were supposed to be visible cyan or converted to transparent areas.

Unless of course the "transparent" Cyan was 0, 255, 255, and the displayable cyan was 1, 255, 255.

Risen · Post by **Risen** » Thu Apr 01, 2004 9:59 pm

Cyb wrote:With most (all?) graphics tools, for example, I'm pretty sure you couldn't make a patch with all 256 colors of the pal in it, though it's perfectly possible.

Obviously. To use 256 colors plus transparency, you'd need either greater than 8-bit depth or an alpha channel.

Edit: Reworded it to make more sense

Post by **Enjay** » Fri Apr 02, 2004 9:09 am

Cyb wrote:most wad tools base transparency conversions on a palette index and not the actual color in the bmp I believe.

Yes, of course. Makes sense.