Difference between revisions of "Sky"

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[[Doom II]] uses the same names for its three sky textures, but the graphics in the [[IWAD]] file are different.  The engine selects SKY1 for the levels MAP01 through MAP11, depicting a brown partly cloudy sky, SKY2 for MAP12 through MAP20, showing a burning cityscape, and SKY3 for MAP21 through MAP32, which somewhat resembles SKY2 from the original Doom but with bright red cave walls behind the mountains, making it clear the player is in a subterranean Hell.  The game is not divided into episodes, of course, but textual interludes divide it into related groups of levels and the sky textures again correspond to the backstory venues: starport, your own home city and alien base (Hell on Earth).
 
[[Doom II]] uses the same names for its three sky textures, but the graphics in the [[IWAD]] file are different.  The engine selects SKY1 for the levels MAP01 through MAP11, depicting a brown partly cloudy sky, SKY2 for MAP12 through MAP20, showing a burning cityscape, and SKY3 for MAP21 through MAP32, which somewhat resembles SKY2 from the original Doom but with bright red cave walls behind the mountains, making it clear the player is in a subterranean Hell.  The game is not divided into episodes, of course, but textual interludes divide it into related groups of levels and the sky textures again correspond to the backstory venues: starport, your own home city and alien base (Hell on Earth).
  
[[TNT: Evilution]] uses an interesting variation: SKY1 is daytime, with an ugly brown sky and snowcapped mountains, and SKY2 is nighttime and filled with stars, with a crude galaxy and a rendering of the Hourglass Nebula covering large portions of opposite sides of the sky.  However, SKY3 is yet another rendering of the Hell sky, here bright red and overcast, with no visible cave wall. [[Plutonia]] uses grayish-white overcast for SKY1, a somber dark red for SKY2, and bright red hell cave wall for SKY3, without any foreground mountains.
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[[TNT: Evilution]]'s SKY1 is daytime, with a brown sky and snowcapped mountains, and SKY2 is nighttime and filled with stars, with a crude galaxy and a rendering of Supernova 1987a covering large portions of opposite sides of the sky.  However, SKY3 is another Hell sky, here bright red and overcast.  
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[[The Plutonia Experiment]] uses grayish-white overcast for SKY1, a somber dark red for SKY2, and bright red hell cave wall for SKY3.
  
 
[[Heretic]] contains three sky [[texture]]s (SKY1, SKY2 and SKY3), one for each episode. SKY1 contains a dark gray overcast sky with brown mountains, SKY2 a cloudy red sky with gray mountains, and SKY3 a deep blue underwater "sky" with blue mountains and large struts visibly supporting the dome. Episode 4 and the three unused levels of "Episode 6" simply use SKY1, whereas Episode 5 recycles SKY3.
 
[[Heretic]] contains three sky [[texture]]s (SKY1, SKY2 and SKY3), one for each episode. SKY1 contains a dark gray overcast sky with brown mountains, SKY2 a cloudy red sky with gray mountains, and SKY3 a deep blue underwater "sky" with blue mountains and large struts visibly supporting the dome. Episode 4 and the three unused levels of "Episode 6" simply use SKY1, whereas Episode 5 recycles SKY3.
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In order to appear out-of-doors, a [[sector]] is given the special ceiling [[flat]] name of F_SKY1 (but see below). This flat is not actually drawn, however. The engine recognizes it as indicating that the ceiling is transparent to the sky beyond, and draws sky above the ceiling height.  The actual sky texture drawn depends on the episode and/or level number as described above.  It is important to note that the sky is drawn similarly to a wall, not like a regular ceiling.
 
In order to appear out-of-doors, a [[sector]] is given the special ceiling [[flat]] name of F_SKY1 (but see below). This flat is not actually drawn, however. The engine recognizes it as indicating that the ceiling is transparent to the sky beyond, and draws sky above the ceiling height.  The actual sky texture drawn depends on the episode and/or level number as described above.  It is important to note that the sky is drawn similarly to a wall, not like a regular ceiling.
  
SKY1, SKY2, SKY3 and SKY4 are in an IWAD file as [[wall texture]]s, each consisting of one or more [[wall patch]]es.  They must be 128 units high.  They are always drawn with their tops at the top of the view window and their zero column at due north. A 1024-wide sky will exactly circumscribe the horizon.  The sky textures in ''Doom'' and ''Doom II'' are only 256 units wide, so they are tiled and repeat four times for each full revolution. The sky patches in Heretic and Hexen are 200-unit tall, but the textures itself are still declared to be only 128-unit tall. The additional height, however, is used and serves to prevent tiling when looking up or down.
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SKY1, SKY2, SKY3 and SKY4 are in an IWAD file as [[wall texture]]s, each consisting of one or more [[wall patch]]es.  They must be 128 units high.  They are always drawn with their tops at the top of the view window and their zero column at due north. A 1024-wide sky will exactly circumscribe the horizon; this effect was first explained in details in the text file accompanying [[The Unholy Trinity]].  The sky textures in ''Doom'' and ''Doom II'' are only 256 units wide, so they are tiled and repeat four times for each full revolution. The sky patches in Heretic and Hexen are 200-unit tall, but the textures itself are still declared to be only 128-unit tall. The additional height, however, is used and serves to prevent tiling when looking up or down.
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The sky texture is mirrored compared to how it appears when used as a texture on a wall.
  
 
==Additional information==
 
==Additional information==
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* SKY1 et. al. may be used directly as wall textures, but then they just look like paintings. They will be mirror images of what they look like when used as sky.
 
* SKY1 et. al. may be used directly as wall textures, but then they just look like paintings. They will be mirror images of what they look like when used as sky.
 
* If the player can see too far down (past the bottom of the sky texture), a seam will appear between texture tiles. Some ports try to prevent this by stretching sky textures, or by making them blur to a solid color past their limits.
 
* If the player can see too far down (past the bottom of the sky texture), a seam will appear between texture tiles. Some ports try to prevent this by stretching sky textures, or by making them blur to a solid color past their limits.
* If two adjacent sectors both have F_SKY1 for their ceiling (or floor), the upper (or lower) texture specified (if any) is ignored.  Sky is drawn instead.
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* If two adjacent sectors both have F_SKY1 for their ceiling, the upper texture specified (if any) is ignored.  Sky is drawn instead. Comments in the code responsible for this effect call it the "[[sky hack]]".
 
* [[Animated wall|Animated]] skies do not work outside of Hexen and certain [[source port]]s.
 
* [[Animated wall|Animated]] skies do not work outside of Hexen and certain [[source port]]s.
* Sky selection is one reason a [[PWAD]] author might select a map slot other than E1M1 or MAP01 (another obvious reason is the [[music]]). Of course, with a little more work the author could provide replacement sky or music lumps; or use port-specific features to choose the sky and music.
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* Sky selection is one reason a [[PWAD]] author might select a map slot other than E1M1 or MAP01 (another obvious reason is the [[music]]). Of course, with a little more work the author could provide replacement sky or music lumps; or use port-specific features such as [[MAPINFO]] to choose the sky and music.
 +
 
 
==Trivia==
 
==Trivia==
*The SKY1 texture was made from a photograph of [http://en.wikipedia.org/wiki/Yangshuo_County Yangshuo Cavern] which was taken by Tom Atwood. The image was on Aris Software's Media Clips.
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*Most Doom and Doom II sky textures were derived from stock images distributed on MediaClips CD-ROM by Aris Entertainment. {{cite web|url={{dwforums|85756|[FOUND] Doom Sky source files}}|author=Blackmantis|title=|publication=[[Doomworld forums]]|publishdate=January 29, 2016|accessdate=February 29, 2016}}
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*The SKY1 texture in The Ultimate Doom was made from a photograph of a [[wikipedia:Yangshuo County|Yangshuo cavern]] which was taken by Tom Atwood (MAJEST3.TIF).
 +
*The SKY2 texture is made from the {{wp|Zion National Park}} (ZION.TIF) in the foreground and another picture for the background mountains.
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*The SKY3 texture is a composition of several sources: the clouds are taken from a picture of white clouds over distant mountains (MAJEST4.TIF), the mountains are partly sourced from another picture (MAJEST5.TIF), other mountains are derived from pictures of stalagmites (probably from the {{wp|Carlsbad Caverns National Park}}).
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*The SKY1 texture in Doom II was made from a photograph of sunset clouds over a beach. (WILD4.TIF)
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*The smoke from the burning city in SKY2 from Doom II was taken from the take off blast of a Space Shuttle launch. (WORLD2.TIF)
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==Gallery==
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<gallery mode=nolines widths=160px>
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File:E1M2 courtyard.png|Knee-Deep in the Dead sky
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File:E2M5 lots of cells.png|The Shores of Hell sky
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File:E3m9 arena.PNG|Inferno sky
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File:E4M6Courtyard.png|Thy Flesh Consumed sky
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File:WaterD201.png|Brown clouds over Doom II's "Starport" episode
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File:MAP12_correct.png|Smoking ruins in Doom II's "City" episode
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File:DoomII MAP23 Spider.png|Red hellish landscape in Doom II's "Hell" episode
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File:Evilution-map10-pool.png|TNT: Evilution's mountain sky
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File:Evilution-map14-start.png|One view of TNT's night sky
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File:Evilution-map19-truck.png|Another view of TNT's night sky
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File:Evilution-map27.png|The red clouds of TNT's hell sky
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File:Plutonia-map06-start.png|Plutonia's white clouds
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File:Plutonia-map13-end.png|Plutonia's red dusk
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File:Plutonia-map25-start.png|Plutonia's fleshy canopy of Hell
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File:Hell Keep PSX.png|The fire sky from the [[Sony PlayStation]] port
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File:Heretic-E1M8.png|The brown mountains of Heretic's City of the Damned
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File:DOOM0025.png|The gray mountains of Heretic's Hell's Maw
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File:Heretic-e5m2-start.png|The vault of water in D'Sparil's undersea domes
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File:Hexen-hub1-bell.png|Dark blue clouds in [[Hexen]].
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File:Hexen-hub1sp-start.png|Bright red sky in Hexen.
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File:Hexenshadowwood.png|The mountains on the brown clouds.
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File:Hexendarkmere.png|Foggy sky
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</gallery>
  
 
==See also==
 
==See also==
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==Sources==
 
==Sources==
 
* [[Unofficial Doom Specs]]
 
* [[Unofficial Doom Specs]]
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 +
==References==
 +
<references/>
  
 
[[Category:Resources]]
 
[[Category:Resources]]
 
[[Category:Doom engine]]
 
[[Category:Doom engine]]

Revision as of 19:15, 12 August 2019

The sky is a special effect built into the Doom rendering engine.

The original Doom contains three sky textures (SKY1, SKY2 and SKY3), one for each episode. This is consistent with the backstory, because each episode takes place in a specific venue (Phobos, Deimos and Hell, respectively), and the nine levels of each episode share the same sky. The first is a misty gray sky with lumpy greenish mountains, the second is a red overcast sky with brown mountains with light snow, and the third is a much foggier red sky with mountains tinted reddish-black. Ultimate Doom added a fourth sky texture, SKY4, for use in Episode 4, showing orange-tinted clouds with no visible mountains.

Doom II uses the same names for its three sky textures, but the graphics in the IWAD file are different. The engine selects SKY1 for the levels MAP01 through MAP11, depicting a brown partly cloudy sky, SKY2 for MAP12 through MAP20, showing a burning cityscape, and SKY3 for MAP21 through MAP32, which somewhat resembles SKY2 from the original Doom but with bright red cave walls behind the mountains, making it clear the player is in a subterranean Hell. The game is not divided into episodes, of course, but textual interludes divide it into related groups of levels and the sky textures again correspond to the backstory venues: starport, your own home city and alien base (Hell on Earth).

TNT: Evilution's SKY1 is daytime, with a brown sky and snowcapped mountains, and SKY2 is nighttime and filled with stars, with a crude galaxy and a rendering of Supernova 1987a covering large portions of opposite sides of the sky. However, SKY3 is another Hell sky, here bright red and overcast.

The Plutonia Experiment uses grayish-white overcast for SKY1, a somber dark red for SKY2, and bright red hell cave wall for SKY3.

Heretic contains three sky textures (SKY1, SKY2 and SKY3), one for each episode. SKY1 contains a dark gray overcast sky with brown mountains, SKY2 a cloudy red sky with gray mountains, and SKY3 a deep blue underwater "sky" with blue mountains and large struts visibly supporting the dome. Episode 4 and the three unused levels of "Episode 6" simply use SKY1, whereas Episode 5 recycles SKY3.

Hexen does skies in a different manner, allowing for two textures to be used at once as well as scrolling textures (Used, for example, in clouds) and thunder and lightning. Skies in Hexen are defined in the MAPINFO lump.

Technical

In order to appear out-of-doors, a sector is given the special ceiling flat name of F_SKY1 (but see below). This flat is not actually drawn, however. The engine recognizes it as indicating that the ceiling is transparent to the sky beyond, and draws sky above the ceiling height. The actual sky texture drawn depends on the episode and/or level number as described above. It is important to note that the sky is drawn similarly to a wall, not like a regular ceiling.

SKY1, SKY2, SKY3 and SKY4 are in an IWAD file as wall textures, each consisting of one or more wall patches. They must be 128 units high. They are always drawn with their tops at the top of the view window and their zero column at due north. A 1024-wide sky will exactly circumscribe the horizon; this effect was first explained in details in the text file accompanying The Unholy Trinity. The sky textures in Doom and Doom II are only 256 units wide, so they are tiled and repeat four times for each full revolution. The sky patches in Heretic and Hexen are 200-unit tall, but the textures itself are still declared to be only 128-unit tall. The additional height, however, is used and serves to prevent tiling when looking up or down.

The sky texture is mirrored compared to how it appears when used as a texture on a wall.

Additional information

  • F_SKY1 may be used for floors as well as ceilings. However, this may cause Hall of Mirrors effect if the player can see too high.
  • Hexen uses F_SKY instead of F_SKY1, and Strife uses F_SKY001. All other Doom-engine games use F_SKY1.
  • SKY1 et. al. may be used directly as wall textures, but then they just look like paintings. They will be mirror images of what they look like when used as sky.
  • If the player can see too far down (past the bottom of the sky texture), a seam will appear between texture tiles. Some ports try to prevent this by stretching sky textures, or by making them blur to a solid color past their limits.
  • If two adjacent sectors both have F_SKY1 for their ceiling, the upper texture specified (if any) is ignored. Sky is drawn instead. Comments in the code responsible for this effect call it the "sky hack".
  • Animated skies do not work outside of Hexen and certain source ports.
  • Sky selection is one reason a PWAD author might select a map slot other than E1M1 or MAP01 (another obvious reason is the music). Of course, with a little more work the author could provide replacement sky or music lumps; or use port-specific features such as MAPINFO to choose the sky and music.

Trivia

  • Most Doom and Doom II sky textures were derived from stock images distributed on MediaClips CD-ROM by Aris Entertainment. [1]
  • The SKY1 texture in The Ultimate Doom was made from a photograph of a Yangshuo cavern which was taken by Tom Atwood (MAJEST3.TIF).
  • The SKY2 texture is made from the Zion National Park (ZION.TIF) in the foreground and another picture for the background mountains.
  • The SKY3 texture is a composition of several sources: the clouds are taken from a picture of white clouds over distant mountains (MAJEST4.TIF), the mountains are partly sourced from another picture (MAJEST5.TIF), other mountains are derived from pictures of stalagmites (probably from the Carlsbad Caverns National Park).
  • The SKY1 texture in Doom II was made from a photograph of sunset clouds over a beach. (WILD4.TIF)
  • The smoke from the burning city in SKY2 from Doom II was taken from the take off blast of a Space Shuttle launch. (WORLD2.TIF)

Gallery

See also

Sources

References

  1. Blackmantis (29 January 2016). [FOUND] Doom Sky source files. Doomworld forums. Retrieved 29 February 2016.