User's Guide ‐ Skybox Preview

Source Level Editor 2.104

Overview

Skybox Preview in Source Level Editor (SLE) can be separated into two modes: 2D Skybox Preview and 3D Skybox Preview.

2D Skybox

"2D" means rendering the six planes forming the skybox, with the appropriate texture on them, the same way the game does. It maintains the illusion of infinite parallax by moving together with the camera, appearing to be infinitely far from it. It cannot be selected or otherwise interacted with, save for changing the texture.
The texture is taken out of the Worldspawn options. If it fails to load, the render defaults to using sky_day01_01 from Half-Life 2.

The skybox is toggled by using the Preview Skybox toolbar button or using the default hotkey, Y. It is rendered in place of faces that have a material with %compilesky or %compile2Dsky parameters.
In turn, those faces become invisible and unselectable in 3D; however, if selected in 2D, or as part of a group or a visgroup, those faces/brushes will be visible.

2D Skybox rendered on HL2's d1_canals_01.

Note that enabling Skybox Preview also turns on Fog Preview.
It takes fog settings from the env_fog_controller entity (if multiple are present, it will prioritise the one with the Master spawnflag).
As of SLE 2.104, fog blending between two colours is not emulated.

3D Skybox

Renders the objects and geometry marked as 3D Skybox, with the scale of the sky_camera entity, and appropriate offset from the map's center.
Requires previwing skybox to work; as in, without drawing 2D Skybox (see above), the 3D Skybox won't be drawn either, so toggle it with the same toolbar button or the hotkey.

The same spot as above, now rendering the 3D Skybox as well.

Note that when 3D Skybox is previewed, fog settings are taken from the sky_camera entity.
As of SLE 2.104, the fog applies to the same map - the 3D Skybox objects are not fogged separately like they are in-game.

Marking selections as 3D Skybox

The process is very simple and is entirely controlled by the user.
Select any objects around the sky_camera you wish to be previewed. Then either open the selection's context menu with the right mouse button and select Mark as 3DSkybox; or go to View->Mark Selection as 3DSkybox.
The selection should now be drawing scaled up and offset in the 3D View; their 'true' position, however, remains where it was.

Context menu (left) and View menu (right) with the relevant items highlighted.

To undo, simply do the same but chose Unmark as 3D Skybox.

Note: the Vertex Edit tool has been updated to show the vertices at the scaled up/offset positions as well.
Also note: the state of being marked as 3D Skybox is not saved in the map document. It will only persist until the document is closed. It is also not retained by copies of the selected objects; mark them again if you need to.

Known issues:

• Select few models don't scale correctly in 3D Skybox. This includes the animated Citadel model in d1_trainstation_06.
• Bounds of the 3D Skybox brushes and its models show without scaling in 2D Views. This is intended, however, some artifacting will be seen when selecting 3D Skybox brushes in 2D.
• 3D Skybox is subject to the max drawing distance limit, so it needs to be extended to see all of it. This can be done in the Options (see the user's guide section on it) or using the 3D Views hotkeys (1 and 2 by default).
• The previewed objects may also not render when flying too far away from their 'real' position.
• To use the context menu with the previewed (scaled up) objects, you need to right-click their 'real' position'.