Free Skyboxes

[Heike Fallago]

Askybox is a method of creating backgrounds to make a video game level appear larger than it really is.[1] When a skybox is used, the level is enclosed in a cuboid. The sky, distant mountains, distant buildings, and other unreachable objects are projected onto the cube's faces (using a technique called cube mapping), thus creating the illusion of distant three-dimensional surroundings. A skydome employs the same concept but uses either a sphere or a hemisphere instead of a cube.

Processing of 3D graphics is computationally expensive, especially in real-time games, and poses multiple limits. Levels have to be processed at tremendous speeds, making it difficult to render vast skyscapes in real-time. Additionally, real-time graphics generally have depth buffers with limited bit-depth, which puts a limit on the amount of details that can be rendered at a distance.

To avoid these problems, games often employ skyboxes. Traditionally, these are simple cubes with up to six different textures placed on the faces. By careful alignment, a viewer in the exact middle of the skybox will perceive the illusion of a real 3D world around it, made up of those six faces.

As a viewer moves through a 3D scene, it is common for the skybox to remain stationary with respect to the viewer. This technique creates the illusion that objects in the skybox are infinitely far away, since they do not exhibit any parallax motion, whereas 3D objects closer to the viewer do appear to move. This is often a good approximation of reality, where distant objects such as clouds, stars and even mountains appear to be stationary when the viewpoint is displaced by relatively small distances. However, designers must be careful about which objects they include in a fixed skybox. If an object of known size (e.g. a car) is included in the texture, and is large enough for the viewer to perceive it as close by, the lack of parallax motion may be perceived as unrealistic or confusing.

The source of a skybox can be any form of texture, including photographs, hand-drawn images, or pre-rendered 3D geometry. Usually, these textures are created and aligned in 6 directions, with viewing angles of 90 degrees (which covers up the 6 faces of the cube).

Simple texture-based skyboxes had severe disadvantages. They could not be animated, and all objects would appear equally distant at infinity. They looked simple and because of certain limits, it was hard for designers to be creative with this feature. But starting in the late 1990s, some game designers built small amounts of 3D geometry to appear in the skybox to create a better illusion of depth, in addition to a traditional skybox for objects very far away. This constructed skybox was placed in an unreachable location, typically outside the bounds of the playable portion of the level, to prevent players from touching the skybox.

In older versions of this technology, such as the ones presented in the game Unreal, this was limited to movements in the sky, such as the movements of clouds. Elements could be changed from level to level, such as the positions of stellar objects, or the color of the sky, giving the illusion of the gradual change from day to night. The skybox in this game would still appear to be infinitely far away, as the skybox, although containing 3D geometry, did not move the viewing point along with the player movement through the level.

Newer engines, such as the Source engine, continue on this idea, allowing the skybox to move along with the player, although at a different speed. Because depth is perceived on the compared movement of objects, making the skybox move slower than the level causes the skybox to appear far away, but not infinitely so. It is also possible, but not required, to include 3D geometry which will surround the accessible playing environment, such as unreachable buildings or mountains. They are designed and modeled at a smaller scale, typically 1/16th, then rendered by the engine to appear much larger. This results in fewer CPU requirements than if they were rendered in full size. The effect is referred to as a "3D skybox".

In the game Half-Life 2, this effect was extensively used in showing The Citadel, a huge structure in the center of City 17. In the closing chapters of the game, the player travels through the city towards the Citadel, the skybox effect making it grow larger and larger progressively with the player movement, completely appearing to be a part of the level. As the player reaches the base of the Citadel, it is broken into two pieces. A small lower section is a part of the main map, while the upper section is in the 3D skybox. The two sections are seamlessly blended together to appear as a single structure.

I have a couple of skyboxes in unity (Day and Night) and want to achieve a smooth transition between them periodically, to create a day and night cycle. I've looked up many questions but they're either outdated or I have no idea what they mean, Any help would be appreciated.

Bryant-Denny Stadium features 163 skyboxes that allow patrons to cheer on the Crimson Tide with privacy and luxury. Skybox holders and their guests enjoy the ultimate game day experience with premium amenities and dedicated hospitality.

Typically nighttime or moon skyboxes appeal to me the most, usually shades of blue, though the maps have to be well suited for it. From iwads, TNT's galaxy is my favourite, although Doom's episodes 1 and 3 both have some very neat ones I normally stop for a second to just stare at them. And from pwads, some that I recall are:

I currently can't put the sky that I wanna say now but, the one that I absolutely love is the sunset sky used in the GL addon of Epic 2 (it uses the secret levels and the maps 21-30). I really like the sky and gives a lot of atmosphere in the maps, especially in the oasis-esque maps.

Since this thread got revived, might as well ask if anyone is able to access the download for theplace.wad? I wanted to download it after seeing the picture but Google Drive showed that I didn't have access to the file, same with the texture pack in the same thread. Only file I could download was Reconstruction/Decomposition through the idgames link.

Hiya there! I've joined Epsilon fairly recently, and one of the primary things I haven't been able to solve on my own is skyboxes. I don't know if it's just a lack of understanding due to there not being any threads on these forums that go in detail about how skyboxes work, if it's an error on my end, or what, but I would really like to be able to make the skyboxes in my phase work!

The current issue I'm experiencing is a mixing of skyboxes. If you set a skybox as your phase default (the only way I know how to change skyboxes, and setting it as zone default doesn't work for me), it seems to keep that skybox's art, but pull the shading/lighting from whatever other skybox you try to implement with the .phase set skybox zone command, or with the built-in Epsilon skybox changer. I've been toying around, trying to figure out how these skyboxes work for about two weeks now, with no luck aside from being able to change the skybox in -all- zones, instead of specific ones. I've tried the .phase reset skybox all CONFIRM command, and tried to retrace my steps, and only get the same error. In the end of this topic, I'm going to include screenshots of my process.

I don't need a mod to swoop in and repair my phase, because that doesn't teach me what's going wrong. It'd be really cool if someone could sit me down and explain how to make separate skyboxes work in different zones/subzones! Thank you in advance!

Images of the errors/process v

I'm not really sure how to look up the spell-based skyboxes, because they seem to be fairly limited (not having every zone's skybox). Even if it's complicated, I'd be willing to read through a coder-language version of it, because the past two months I've been on Epsilon and messing with phases in general, plus trying to figure out skyboxes, I can't figure it out.

I am currently working with Warner Brothers Games as a senior world artist. In the past I worked with studios like 343 Industries and Turn10 studios. I worked as a Skybox Artist on Halo4 and Halo5. I had taken on the role of a cinematics artist as well during my stint at Turn 10 working on creating in engine cinematic content for Forza Motorsports 5. You can see some of my work at www.mukulsoman.com

Multi-layered skyboxes are no different from regular skybox work but like you said depending on the needs they might have to be animated in different ways. For example, on Halo 5, I had to work on a space elevator sequence where the player has to go from space all the way to the surface of a planet. Now that was not an easy problem to solve because no one really knew how exactly to solve this issue because it had pretty much never been done before in a game. It was a great problem solving exercise for me! What we ended up doing was, I made 3 skyboxes (one for the planetary view from space, one for the stratospheric level and one for the terrain level) one below the other and the animation team animated them upward, which made it look like the elevator moved downwards. The parts where there was a hard transition from one skybox to another, we made the elevator go into a covered section so that the transition will be appear to be seamless to the player.

Clouds provide great opportunity for movement and a sense of atmosphere. They are critically important to make a skybox look believable. I create my clouds either procedurally using Vue or Terragen or by using photographs and extracting the clouds out along with an alpha map using photoshop and then mapping them onto a card geo and then strategically placing and blending them into the sky using vertex alpha functionality. Movement is then added using shaders with Uv Scrolling functionalities.

The real key to moving elements in skyboxes to look believable is to keep the movement subtle and not too exaggerated. Skyboxes usually contain elements that are massive and far, so tend to move slowly. While placing such elements in the sky its also important to follow the compositional clues that can be picked up from the over all level too so that the player is not too distracted and overwhelmed with detail and movement.

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