Skinner’s Den

Discussion and information relevant to creating special missions, new ships, skins etc.

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cim
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Re: Skinner’s Den

Post by cim » Wed Sep 09, 2015 6:41 am

Fritz wrote:and the mostly transparent ..._diffuse.png. Or do these files hide something I can't see?
The _diffuse.png is what you want. It's an RGBA image file. The RGB channels are used for the diffuse map (paint), and the A (alpha, or opacity) channel is used for the emission map (glows). If you open the file as a whole in a graphics program, then it will look mostly transparent since most of the ship has no glows and therefore when read as a normal picture an opacity of 0 - any decent paint program will have a way to separate the channels out. Ideally you want to separate them RGB+A, but in some programs you may have to do that by separating them to R+G+B+A and then recombining the first three. Then you'll have a normal non-transparent texture file, and a separate greyscale image where the brightness of the image determines the glow intensity at that point on the texture.

It's done this way because we're only using single-colour glows on the basic textures, so this means we only need one texture file rather than two.

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Re: Skinner’s Den

Post by Diziet Sma » Wed Sep 09, 2015 7:13 am

cim wrote:any decent paint program will have a way to separate the channels out. Ideally you want to separate them RGB+A, but in some programs you may have to do that by separating them to R+G+B+A and then recombining the first three. Then you'll have a normal non-transparent texture file, and a separate greyscale image where the brightness of the image determines the glow intensity at that point on the texture.
And when you're done making changes to the file, you'll need to recombine all four channels before saving...
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Re: Skinner’s Den

Post by Amah » Wed Sep 09, 2015 11:33 am

just follow cim's and diziet advices. And if you need help in German send a pm. Otherwise I made a small howto for GIMP for my noshaders projects. I think it's in resources. or you might check the ocpc customisation (haven't done the python, tho) that's also dealing with the RGBA textures.
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Re: Skinner’s Den

Post by Fritz » Wed Sep 09, 2015 3:37 pm

My English is not the problem, it's more that I've not done very much with graphics. I can make complex 3D models with SketchUp, but I would fail with colouring and texturing. Photoshop is far too complex for me, and I haven't done very much with Gimp. For simpler changes to bitmaps I usually use a 1990s version (!) of MGI PhotoSuite SE that came with my first scanner... :roll:

I'll play I little around with Gimp and let you know if it works or not!
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Re: Skinner’s Den

Post by Amah » Wed Sep 09, 2015 4:29 pm

Good luck then.

For a start:
Splitting RGBA is found under "Colours-> Components-> Decompose-> RGBA"
Joining RGBA is the other way round: "Colours-> Components-> RGB"
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Re: Skinner’s Den

Post by Fritz » Wed Sep 09, 2015 9:54 pm

Amah wrote:Splitting RGBA is found under "Colours-> Components-> Decompose-> RGBA"
Thank you! I didn't have much time this evening, but I tried this, and at least I now can see something that looks like a Python!
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Re: Skinner’s Den

Post by Diziet Sma » Thu Sep 10, 2015 4:25 am

Fritz wrote:I'll play I little around with Gimp and let you know if it works or not!
Be sure to install GIMPs help file as well. It's a separate download. Not only will that give you the help files, it enables the context-sensitive help. Select a tool or menu item, etc, press F1, and the help info for that item will pop up, explaining what all the options for it will do. Very handy.
Last edited by Diziet Sma on Thu Sep 10, 2015 5:13 am, edited 2 times in total.
Most games have some sort of paddling-pool-and-water-wings beginning to ease you in: Oolite takes the rather more Darwinian approach of heaving you straight into the ocean, often with a brick or two in your pockets for luck. ~ Disembodied

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Re: Skinner’s Den

Post by Amah » Thu Sep 10, 2015 4:40 am

you have to do both steps... split into RGBA (keep the A channel somewhere, you'll need it later) and then join it to RGB to get a coloured one plane diffuse texture. I was vague about that, sorry.

for decals: use an extra layer for easier positioning on the texture and in the end later merge all layers.
for colour variations,: colours ->hue-saturation -> change colour channel from all to e.g. magenta (in case you want to colour all magenta'ish bits) and then use the sliders...

And follow diziet's advice. The help files come in quite handy to check back. Other than that feel free to ask,

Have fun.
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Re: Skinner’s Den

Post by Fritz » Fri Sep 11, 2015 12:02 pm

At the moment I'm trying to learn Gimp, as even trivial tasks like copying and mirroring seem to be much more complex than in my familiar graphics program (which doesn't support layers). And I'm still figuring out how to "paint" coloured stripes and things like that over the hull without destroying the structure. I did something like this many years ago and I know it must be possible somehow.

Btw, I found out that the Python-trader texture is a little bit faulty (asymmetric). That doesn't make things easier because doing one side and than mirror it is not possible.
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Re: Skinner’s Den

Post by Amah » Fri Sep 11, 2015 4:02 pm

for the stripes it "easiest" to use a second layer, set opacity to 75% either Dodge or Overlay. This way the underlying structure is combined with the stripes of the new layer.

You also could set Opacity for the burshes, but the first solution is cleaner if you changed about the percentage your mind along the editing :-)
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Re: Skinner’s Den

Post by Fritz » Sun Sep 13, 2015 2:09 pm

Yes, I experimented with opacity too. You must make the colour a little bit more intense, but it works. Before I discovered this, I found another solution: Having real decals in mind, I wouldn't simply stick them over the corners, gaps and hatches, so I made the decals in several smaller pieces. But I still can use opacity to make them look a little older (showing the structure of the underlying hull plates).

Now the only thing I have to do is to recreate a 4 layer PNG. That's my goal for today!
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Re: Skinner’s Den

Post by Smivs » Sun Sep 13, 2015 2:56 pm

Reducing opacity as you've found can alter the colour which is inconvenient, but it also gives a uniform effect which can actually look un-natural if left like that. I've found a better approach is to apply the colour then go for something like 90% opacity just to wash the colour out a tiny bit. Then selectively erase areas to simulate un-even wear. Use something like the Big Galaxy brush. Start with a large brush on low opacity, then make the brush smaller and raise the opacity a bit and erase again, then smaller still and higher opacity. With a bit of experimenting and practice you can produce areas of wear that 'fade out' from the centre. You can then do something similar with full (non-transparency) colour to add some areas of new paint to simulate repaired areas - use a large fuzzy brush etc for this.
This results in a finish that looks like mostly established paint with areas of more extreme wear as well as new patches - take a look at the Python below.

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Re: Skinner’s Den

Post by Fritz » Mon Sep 14, 2015 12:38 am

Fritz wrote:Now the only thing I have to do is to recreate a 4 layer PNG. That's my goal for today!
In retrospective I shouldn't have played Oolite so much today... :roll:

I'm still stuck somehow. Gimp creates new files in every step concerning the splitting and combining of the layers, and in the end I have a nice 3 channel PNG but the alpha channel is lost.

That's what I did so far:
1) Open the original file "... diffuse.png"
2) Colours-> Components-> Decompose-> RGBA. This creates a file with 4 layers R, G, B, and A.
3) Colours-> Components-> Compose-> RGB (I'm not sure what the menu is called in the English version of Gimp, as I'm using the German version). This joins the R, G, and B layers and creates a "normal" RGB bitmap as a separate PNG file.
4) I can change this file by simply painting to it or by adding new layers with decals, the last step being to join all layers. Everything said about decals, surface structure and opacity is part of this step.

But now what? I probably have to import the alpha channel from the decomposed file created in step 2. But I can't figure out how to do it. I also tried try to import my decal layer into the original file or into the file created in step 2) but so far I haven't succeeded in getting the desired result.

It has become late. Maybe tomorrow evening...
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Re: Skinner’s Den

Post by Amah » Mon Sep 14, 2015 4:47 am

Code: Select all

* Copy the emmission map/former alphachannel (from step2)  to the clipboard.
* DE: "Ebene -> Maske -> Ebenenmaske hinzufügen -> Schwarz (volle Transparenz)
  EN: "Layer -> Mask -> Add Layermask -> Black (full transparency)
 ---> you will get now a fully transparent RGBA picture
* Paste the lightmap
* export to png
* done.
About adding the stripes and decals... I use transparency for decals and stuff, but I play around with different layer combination like dodge, burn and overlay, grain merge).
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Re: Skinner’s Den

Post by Fritz » Mon Sep 14, 2015 11:27 pm

Ok, thank you that seems to work! Now I have a PNG file that behaves exactly like the original diffuse PNG - at least in Gimp. I included it into my shipdata.plist, but Oolite still shows the old texture. I'm not sure why, but I probably made a stupid mistake somewhere. Or does Oolite simply ignore PNG files that have some strange properties?

The "artwork" part will be more fun, getting used to Gimp and trying to work with the different brush types and filters. Even the "coffee stain" effect looks good on a battered Python!
"You wouldn't kill me just for a few credits, would you?" – "No, I'll do it just for the fun!"

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