Experimenting with a star ship map - need some help

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Davitch
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Experimenting with a star ship map - need some help

Post by Davitch » Sat Aug 01, 2015 4:58

I am trying to make a map that takes place on star ship, and have some issues/questions regarding using scrolling starry linedef textures to give the impression of flying through space. I know I could do way better with a skybox and (G)ZDoom but it's important to me that this .wad retains PrBoom+ compatibility while also working in ZDoom. I've constructed a small map with a cockpit, window, and a pointy triangle-ish 'room' that contains the star textures. I've set this room's floor to -1024 and ceiling to 1024 (so the floor and ceiling aren't visible) while having the floor of the ship's cockpit at zero, then set either star-textured linedef of the triangle to 'Scroll Wall According To Line Vector'. After looking at the result, I wanted to make it more complex by adding a stack of starry double-sided linedefs with transparent middle textures (just stars with cyan instead of black background.), and making those scroll at a different speed. The first issue I had was getting the transparent middle textures to stay put vertically if I used Scroll According To Line Vector (No matter what the vector is, it doesn't seem to work). I then tried 'Scroll According To Sidedef Offsets', but that involves keeping the y offsets at zero while having the the textures stacked (at -384/-256/-128/0/128... etc.) so I used different sectors with varying ceiling heights in conjunction with 'Create Fake Ceiling And Floor' so that you can see the background stars through the ceilings of the other sectors. That's when I encountered a strange slimetrail-like glitch. It may well in fact be a
slimetrail, but it doesn't seem to be quite the same and only appears in ZDoom (Not PrBoom+). It's like a vertical line that takes a triangular chunk out of the middle texture of one of the foreground stars linedefs. Maybe an issue with my Nvidia drivers or something. The other thing I'm wondering is if there is a better way to do all this while keeping boom compatibility, like a way to trick the engine into wrapping the middle texture from floor to ceiling? I know ZDoom has this as a basic feature, but alas I am stubborn. I know this is all quite complicated. Maybe I should just upload the map here if someone can instruct me how to. Thanks in advance.

Update: Added the wad file as an attachment.
Attachments
Starship (Starfield partially implemented).wad
(79.68 KiB) Downloaded 27 times
Screenshot_Doom_20150731_154517 Scaled Down.png
Is this a slimetrail?
Screenshot_Doom_20150731_154517 Scaled Down.png (400.5 KiB) Viewed 765 times

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Rex Claussen
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Re: Experimenting with a star ship map - need some help

Post by Rex Claussen » Sat Aug 01, 2015 14:07

Great to see you experiment with advanced mapping, Jeff.

Alas, I have experience only with vanilla and (G)ZDooM mapping. I've never done mapping with Boom and PrBooM+ features, so I don't know if I can help. However, here's a suggestion: have you considered using a string of textures for the starfield instead of a single static texture that scrolls? It may require some graphic editing if a ready-made texture is not available. Here is what the texture would be:
  • 1. Start with a 256*128 black canvas.
    2. Insert large white stars to represent the foreground.
    3. Copy that image to another 256*128 canvas, but shift the stars to the left.
    4. Create as many more of these canvases with stars shifted to the left as you need.
    5. Open your first starfield texture, and insert small white stars in the background.
    6. Repeat Steps 3 & 4, BUT SHIFT THE STARS MUCH MORE SLOWLY. This will give the illusion of the distant stars scrolling more slowly than nearby stars.
    7. String all of the textures together to create a long texture that you can scroll
    7. Flip all the textures and edit to create the right side starfield (or simply reverse the scrolling direction)

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Davitch
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Re: Experimenting with a star ship map - need some help

Post by Davitch » Tue Aug 04, 2015 22:07

Hey, I'm back. Thank you Rex for the idea! I take it you mean for the starfield texture to be animated? I really like that idea, and I'm definitely going to go with it. It beats trying to stack middle textures of double sided linedefs.

The only thing that remains is this strange bug I've encountered: As mentioned it only appears in ZDoom 2.7.1 (Though I haven't tried other versions of ZDoom), not PrBoom+ 2.5.1.3 or 2.5.1.4 Test. Also, the texture glitching only seems to happen with middle textures that are mostly cyan (the foreground stars in this case), and that have a similar angle to the 1 sided linedef behind them. Additionally this only happens to the left side of the starfield. I know pretty much for sure that for the glitch to occur the texture must be mostly transparent cyan because I've tried other textures both with and without cyan and either custom or Doom II stock textures. It only happens with the foreground star texture. I would be posting this in the ZDoom.org bugs forum, but I don't have an account there. Can someone please confirm whether I am doing something with the texture that's causing this or if this is a ZDoom specific bug? Some additional info: I'm using palleted PNG images with a compression factor of 9. Doom Builder 2 latest version for mapping, and Slade 3 to import/convert the textures. My video card driver is Nvidia GeForce version 353.62. Attached is another screenshot from a different build of the map showing the glitch. Again, sorry I'm posting this in the wrong place. Many thanks in advance.
Attachments
Screenshot_Doom_20150802_164550 Scaled Down.png
I didn't save this build, but if needed I can reproduce the effect in a different map.
Screenshot_Doom_20150802_164550 Scaled Down.png (358.81 KiB) Viewed 735 times

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Rex Claussen
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Re: Experimenting with a star ship map - need some help

Post by Rex Claussen » Fri Aug 07, 2015 16:38

I take it you mean for the starfield texture to be animated?
Yes, animate the starfield texture.

As for your texture glitching problem, unfortunately I have never had to deal with such a problem, so I can't be of any help. However, if you use an animated & scrolling texture on a one-sided linedef, you'll get rid of the translucent 2-sided linedef in the front on which you relied for the illusion of stars moving with variable speeds.

Upon re-reading your second post, it occurred to me that your problem might be caused either by using a translucent texture or by using stacked 2-sided linedefs. Have you considered creating a very tall translucent texture (i.e., use a 128 x 128 patch, but use the TEXTURE lump to make a 128 x 2048 texture). If the glitch is being caused by stacking linedefs this may take care of the problem.

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Davitch
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Re: Experimenting with a star ship map - need some help

Post by Davitch » Sat Aug 08, 2015 0:33

Thanks for the reply again Rex, and for the idea of making a tall texture to avoid using stacked textures. I have actually created a different map with a 2048x508 (508 is the height limit of a wall texture in PrBoom+ I think) texture for additional foreground stars. The bug is still happening even without using the special Create Fake Floor And Ceiling. Could someone reading this with a ZDoom forums account and the time to spare please report this issue on there and link to this thread? I would go ahead and post in the GZDoom forums here but that would further disorganize things. I also would attach the newer map demonstrating this effect but as it is it has almost 5 megs of textures...

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Rex Claussen
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Re: Experimenting with a star ship map - need some help

Post by Rex Claussen » Sat Aug 08, 2015 14:04

Davitch wrote:Could someone reading this with a ZDoom forums account and the time to spare please report this issue on there and link to this thread?
Done.

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NeoHippo
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Re: Experimenting with a star ship map - need some help

Post by NeoHippo » Sun Aug 09, 2015 20:21

The first thing I did was to eliminate the acute angle at the top, like so

Image

Then I ran the map with ZDoom. The effect is very much dependant on the screen resolution

Image

The higher the resolution, the more noticeable the effect at the top.
In any resolution, I could not see a slimetrail.

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