Author Topic: P-38 Skin Build Log  (Read 5084 times)

Offline Greebo

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P-38 Skin Build Log
« on: September 29, 2019, 05:13:12 AM »
I've been asked to skin a P-38G for a scenario to be held in a couple of months and as this involves me creating a new skin template for what is a very old AH2 shape I thought I'd document the process here. That way if the P-38 shapes get updated in the near future at least this work is not a complete waste of time. This will be a bit like the plastic kit build log threads you get on modelling sites with posts showing progress, but also with how I do things like panel lines, rivets, shadows, camouflage schemes, weathering and lighting effects. In between posts I'll try to answer whatever questions anyone may have. Perhaps other skinners can add their alternative ways of doing things.

So to begin the new skin I open the AH skin viewer, select the P-38G and hit “Save Textures”. I navigate to the new p38g folder, delete all the files in it except the three that texture the outside of the aircraft; p38g1.bmp, p38g1_n.bmp and p38g1_s.bmp. A shortcut to this working folder is placed on my desktop and into the folder go shortcuts to both the skin viewer and a “P-38G Info” folder I've created containing useful drawings and photos collected off the web.

To create the working file I open p38g1.bmp in my paint program PaintShop Pro and then save it as a “pspimage” file, which is PSP's native file format.

So in the working file p38g1.pspimage I have the default skin image displayed as a single layer, which I rename from “Layer 1” to “Default skin”. Naming every layer clearly is a very good habit to get into as there will be a whole load of layers created before the skin is finished.

What I want to do next is examine the skin shape for issues that are going to affect how well I can skin it. To help me with this I am going to use a uv mapper, which is a square image files covered in different coloured squares, lines and numbers. When applied to a skin it can help define where and how the different 2D areas of the bmp (known as uvs) are displayed on the 3D shape. An image web search for “uv mapper” will reveal various ones you can download for free.

To make use of the uv mapper I copy and paste it into my working file as a new layer positioned above the original default skin layer. After saving the working file I do a “Save Copy As” into the working folder using “bmp” as the file type. This overwrites the original default skin's bmp file with one showing my uv mapper.

For anyone new to skinning the reason for these file format conversions is that the skin viewer (and the game) can only see bmp files so it is always necessary to convert a copy of the working file back to that format in order to view any changes made to it. In its native format a paint program can split the image up into many different layers and then save it this way, something that is not possible using the single layer bmp format.

Switching back to the skin viewer I hit the “Refresh” button to view the new version of the diffuse file I have just created and also click the “No Lighting” button to get rid of any unwanted lighting effects generated by the default p38g1_n.bmp and p38g1_s.bmp files. You can see the effect of the uv mapper in the screenshots below:-



The mapper reveals a number of issues with this very early AH2 P-38G shape, things you get less of on on the later AH2 shapes and not at all on the AH3 ones:-



First various parts of the shape are scaled far differently to each other on the bmp. The horizontal tail's uv has been made much smaller on the bmp relative to the wings and fuselage etc. and this makes the uv mapper's numbers appear much larger on it when viewed in the skin viewer. This is a problem because one pixel wide panel lines will appear to be much wider on the horizontal tail than similar one pixel wide lines will on the rest of the aircraft. There's not much that can be done about this except to make the fat lines on the tail fainter to compensate.

Another problem is that there is some texture stretching running laterally across the extreme top and bottom of the fuselage and tail booms. This is because their textures have been projected horizontally from the left and right rather than wrapped around the shape. What this means is that the only detail that can be applied to these areas is that which runs laterally, i.e. panel lines that run from left to right. Because of this I won't be able to paint the gun troughs onto the nose as the middle troughs will get stretched laterally.

The reversed numbers on areas like the inner tail booms mean these areas are applied to the shape backwards from how they appear on the uv. This means anything like text painted onto those parts must be reversed as well. A bigger issue is that it also reverses the bumps on the normal file so sunken panel lines will appear raised and so on. There is a way round this which I'll explain when we get to the normal map.

The relatively low polygon count shows in things like hinge lines not being defined in 3D. Finally there is some copying of uv data, one uv being used for all three wheels and another for both bomb racks.

I mentioned before the unwanted lighting effects generated by the default p38g1_n.bmp and p38g1_s.bmp files. Turning “All Lighting” back on in the viewer shows the effect in the following screenshot:-



There are fasteners, panel lines and tyre treads visible as light and shadow generated by the default normal map. I'm going to create my own version of this bump data later that matches my own panel lines etc. so I want to get rid of the default data as it'll be a distraction. Also I'd like to get some more realistic lighting as “No Lighting” looks very flat and the default skin's lighting has highlights that are too powerful and concentrated.

You might think deleting the p38g1_n.bmp and _s files would disable them but it won't, the viewer and game still uses the default files if none are present in the folder. Luckily there is an easy way to get reasonable lighting: I open the p38g1_n.bmp file in PSP, use a colour picker to select the background purple colour, hit the flood fill button and save the file. This creates an image which is entirely one colour and therefore generates no bumps on the skin. I then do the same to the _s file, flooding it with one shade of dark grey and then saving it.

There are a couple of other lighting effect files that the default P-38G skin isn't using. To create these I copy and paste the modified p38g1_s.bmp twice and rename these copies p38g1_p.bmp and p38g1_e.bmp. Opening these copies in PSP I make them both a bit darker, almost black, and then save them.

With these blank lighting files enabled I hit “refresh” in the skin viewer to view the results:-



The annoying panel line and fastener bumps are gone and the lighting looks a lot more natural for a matt paint job than either with “No Lighting” or with “Lighting” using the default files.

That's it for now, next time I'll discuss laying out new uvs and drawing panel lines.
« Last Edit: September 29, 2019, 05:16:55 AM by Greebo »

Offline Devil 505

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Re: P-38 Skin Build Log
« Reply #1 on: September 29, 2019, 08:38:14 AM »
Most excellent.
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Offline Vraciu

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Re: P-38 Skin Build Log
« Reply #2 on: September 29, 2019, 01:37:51 PM »
Wish I had understood that panel line finder when I was starting out.  Whew.   Nice.  When I am finished with the 51s maybe I can help on a couple of 38s.   I’ll wait and see what you do with one first.   :D
« Last Edit: September 29, 2019, 01:39:30 PM by Vraciu »
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Offline FTJR

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Re: P-38 Skin Build Log
« Reply #3 on: September 30, 2019, 02:21:34 AM »
Thanks Greebo
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Offline Nefarious

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Re: P-38 Skin Build Log
« Reply #4 on: September 30, 2019, 07:48:15 AM »
Looking forward to it's progression.
There must also be a flyable computer available for Nefarious to do FSO. So he doesn't keep talking about it for eight and a half hours on Friday night!

Offline puller

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Re: P-38 Skin Build Log
« Reply #5 on: September 30, 2019, 08:26:29 AM »
Awesome Greebo :rock :rock :rock
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Offline oboe

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Re: P-38 Skin Build Log
« Reply #6 on: October 01, 2019, 07:01:30 PM »
Nice work, Greebo.  I'm not sure how much I remember about the P-38 skins, but if you think I might be of help in any way don't hesitate to PM me.  I still have the PSD files somewhere with rivet, screw and panel line layers, etc.  for "Beautiful Lass", which I think was the last P-38G skin I created.  Also, IMHO, for reference there is nothing better than Fester's hyper-detailed P-38 skins.

While searching through my skin backups I found a P-51D I completed but apparently never showed - I couldn't find any reference to it in the BB search I did anyway.  It's "Fragile But Agile" from the 348th FG.   I must not have thought it was worth showing - I did alot of P-51D skins while I played around with trying to get natural metal to look right.





Offline Vraciu

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Re: P-38 Skin Build Log
« Reply #7 on: October 01, 2019, 08:08:16 PM »
Don't want to hijack Greebo's thread here, but that's very nice work, Oboe. 
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Offline lyric1

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Re: P-38 Skin Build Log
« Reply #8 on: October 01, 2019, 11:50:27 PM »
but that's very nice work, Oboe.

Yes indeed.

Offline Greebo

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Re: P-38 Skin Build Log
« Reply #9 on: October 02, 2019, 03:17:00 PM »
Nice work, Greebo.  I'm not sure how much I remember about the P-38 skins, but if you think I might be of help in any way don't hesitate to PM me.  I still have the PSD files somewhere with rivet, screw and panel line layers, etc.  for "Beautiful Lass", which I think was the last P-38G skin I created.  Also, IMHO, for reference there is nothing better than Fester's hyper-detailed P-38 skins.

That is a great looking skin Oboe.

I am most of the way through creating my own panel lines and hope to be able to write a post describing the process this weekend. I have been using walkaround photos and panel line diagrams as references. I had a quick look at the default P-38G skin but it actually uses P-38J panel lines and has various other issues which make it not much use to me. Thanks for the offer, I'm sure yours and Cit's P-38 skins are excellent but I like my skins to be my work as much as possible. Also skinners reading this thread probably wouldn't have access to them as a reference so it would kind of defeat the purpose of it to use them.


Offline oboe

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Re: P-38 Skin Build Log
« Reply #10 on: October 02, 2019, 05:07:56 PM »
Thanks guys, and I understand your desire to do all the work yourself, Greebo.   I'm sure it'll be top hole; I'll check back to follow your progress. 

Curious about that new P-38 3D model though - I wonder what happened to it?

<S> guys  :salute 

Offline Devil 505

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Re: P-38 Skin Build Log
« Reply #11 on: October 02, 2019, 05:16:56 PM »
Curious about that new P-38 3D model though - I wonder what happened to it?

It never was, most likely.

Also, great looking Pony, Oboe.
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Offline Guppy35

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Re: P-38 Skin Build Log
« Reply #12 on: October 03, 2019, 12:08:50 AM »
Thanks guys, and I understand your desire to do all the work yourself, Greebo.   I'm sure it'll be top hole; I'll check back to follow your progress. 

Curious about that new P-38 3D model though - I wonder what happened to it?

<S> guys  :salute

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Offline Greebo

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Re: P-38 Skin Build Log
« Reply #13 on: October 03, 2019, 03:44:16 AM »
Curious about that new P-38 3D model though - I wonder what happened to it?

I did do a P-38 skin for an exterior-only 3D shape that HTC bought-in while Waffle was busy with AH3 development but I doubt it will ever get used. IIRC at the time Waffle told me to "take a look at it" but I jumped the gun and did a skin for the thing. However HTC changed their requirements for how new 3D object shapes are built before AH3 was finished and this bought-in P-38 shape didn't meet them. Because of this no interior work was ever done on it and I think that any new P-38 will need a new shape and skin. Since AH3 HTC have concentrated on updating AH1 planes. For some strange reason HTC displayed this trial P-38 shape with my skin in an advert, which is why some players know about it and why I feel OK to talk about it.

One of the requirements that changed between AH2 and AH3 is that no zero-thickness parts are allowed in new objects and this bought-in P-38 shape had some. To reduce poly count AH2 plane shapes have things like gear doors that are made up of a 2D geometric shape with an inner and outer texture but no edges. In AH3 this could cause a problem with flickering shadows due to Z fighting between the inner and outer textures occupying the same 3D space, so to get round this HTC had to give shadows in the game a slight seperation from the object that casts them. This shadow gap looks less bad than the flickering would. I seem to recall AH3 objects have a flag that can be enabled to get rid of their shadow seperation but it has not enabled it in the game code yet.

The good thing about this is that I do already have quite a bit of info on the P-38, both in books and stuff found on the internet. BTW I'm not going to show the previous skin I did because I don't think HTC would want me to.
« Last Edit: October 03, 2019, 04:06:56 AM by Greebo »

Offline Devil 505

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Re: P-38 Skin Build Log
« Reply #14 on: October 03, 2019, 08:53:01 AM »
Thanks for the info about this Greebo.
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