Newxog global

newxog_global is a logical entity available in Black Mesa. Xog (short for Xen Fog) is Screenspace Fog, very flexible new fog system that replaces Source's legacy fog. The new xog can be configured on the fly with instant results ingame, it can change over time with I/O, and it can vary in density and color based on height. Along with its tons of options, is that it became (sort of) the preferred way for level designers to do color corrections in the xen part of the game instead of the old color correction entity provided by Source Engine. Uses radial fog instead of deprecated planar/z fog. On top of 3 colors for blending, it support both 1D and cubemap gradient textures. The game also have console-based Xog Editor which can select and edit almost every property of any xog entity.

Class hierarchy
CNewXogGlobal ↳CBaseEntity

newxog_global in bm_c4a1b.

Important:This entity doesn't affect optimization, this entity is for visual effects only. Combine with env_fog_controller.

Todo: Rework page and replace .gif files with video links.

Keyvalues

Enabled (Enabled) <choices>

Determines is this entity enabled or disabled on spawn.

• 0: Enabled
• 1: Disabled

Xog Type (xogtype) <choices>

Determines xog type.

• 0:0: Global - render xog in world space only.
• 1:1: GlobalWithSky - render xog in world space and add third layer for skybox (without color blending, uses skyColor instead).
• 2:2: SkyOnly - xog will be applied to skybox with color blending, skyBlendFactor will not work, decreased intensity will show a "black void" instead of skybox.

Examples

Global GlobalWithSky SkyOnly

Important:You can have only one GlobalWithSky or Global with SkyOnly (separately as well) in your level. Otherwise, game will crash on map launch with this engine error message.

• 

  The engine error message.

skyColor (skycolor) <color255>

Xog color in 2D skybox.

Examples

skyColor - 255 0 0. skyColor - 0 255 0. skyColor - 60 0 180.

skyBlendFactor (skyblendfactor) <float>

Xog intensity in skybox. This is a float value from 0.0 to 1.0.

Examples

skyBlendFactor - 0.0. skyBlendFactor - 0.5. skyBlendFactor - 1.0.

Color Mode (colormode) <choices>

Determines color mode. With StaticColor doesn't affects color in skybox. With 1DGradTexture, color will depends on texture from Grad Texture, doesn't affects color in skybox.

• 0:0: StaticColor - xog will use colors from colorBottom and colorTop. Also will blend the colors. For 2D skybox, it will use color single color from skyColor (if used GlobalWithSky xog type).
• 1:1: 1DGradTexture - xog will use texture from Grad Texture and use it as 1D texture.
• 2:2: CubeGradTexture - xog will use texture from Grad Texture and use it as cubemap texture, it will use black color for xog the fog and will not use colors from the properties.
  Tip:Follow this steps if you want to create your own texture for this color mode.

Examples

StaticColor 1DGradTexture (in this picture, xog doesn't use any texture, the engine replaces missing texture with the chessboard, this is why the color is purple. CubeGradTexture (used lights/lightcookie_int_cyst texture).

Grad Texture (texname) <string>

Grad texture to use. Grad texture uses .vtf file and not .vmt. Works only if Color Mode value is 1DGradTexture or CubeGradTexture.

colorTop will use texture itself to render, colorBottom will use main color of chosen texture to render.

htZColStart will set texture position. htZColEnd will scale texture.

htZStart will set main color start position, htZEnd will scale main color.

With Global and GlobalWithSky xog type, it will be applied only in world space. With SkyOnly, it will be applied in skybox. If you want to have it for world space and sky together - you can use 2 entities as workaround, first xog will use Global type, second will use SkyOnly type.

Example of how it works with Global and GlobalWithSky.

Used dev/xog_grad_1d.vtf texture. Using Xog Editor to change values.

Example of how it works with SkyOnly.

Used dev/xog_grad_1d.vtf texture. Using Xog Editor to change values.

colorTop (colortop) <color255>

Xog top color.

Examples

colorTop - 255 0 0. colorBottom - 60 0 180. colorTop - 0 255 0. colorBottom - 60 0 180. colorTop - 255 255 0. colorBottom - 60 0 180.

colorBottom (colorbottom) <color255>

Xog bottom color.

Note:Top and bottom colors blending in xog center, for example with red and green colors the center of xog will be yellow.

Examples

colorTop - 255 0 0. colorBottom - 0 255 0. colorTop - 255 0 0. colorBottom - 0 0 255. colorTop - 255 0 0. colorBottom - 255 255 0.

distStart (diststart) <float>

Xog start draw distance.

Examples

distStart - 150. distEnd - 150. distStart - 1000. distEnd - 150. distStart - 1500. distEnd - 150.

distEnd (distend) <float>

Xog end draw distance.

Examples

distStart - 150. distEnd - 150. distStart - 1000. distEnd - 1000. distStart - 1500. distEnd - 1500.

distDensity (distdensity) <float>

Density of xog entity, only values from 0 to 1 works.

Examples

0.0 0.5 1.0

opacityOffsetTop (opacityoffsettop) <float>

Offsets top color of xog.

Examples

opacityOffsetTop - 0.0. opacityOffsetTop - -0.5. opacityOffsetTop - 0.5.

opacityOffsetBottom (opacityoffsetbottom) <float>

Offsets bottom color of xog.

Examples

opacityOffsetBottom - 0.0. opacityOffsetBottom - -0.5. opacityOffsetBottom - 0.5.

htZStart (htzstart) <float>

Height that xog starts rendering at.

Examples

htZStart - 80. htZEnd - 0. htZStart - 90. htZEnd - 0. htZStart - 90. htZEnd - 10.

htZEnd (htzend) <float>

Height that xog stops rendering at.

Examples

htZStart - 0. htZEnd - 80. htZStart - 0. htZEnd - 120. htZStart - 0. htZEnd - 400.

htZColStart (htzcolstart) <float>

Height that xog color starts rendering at. Results depend on htZColEnd value.

Examples

htZColStart - 0. htZColStart - 50. htZColStart - 150.

htZColEnd (htzcolend) <float>

Height that xog color stops rendering at. Results depend on htZColStart value.

Examples

htZColEnd - 400. htZColEnd - 100. htZColEnd - 190.

noise1ScrollSpeed (noise1scrollspeed) <vector>

Layer one, speed at which noise moves trough xog volume (X Y Z).

Examples

noise1ScrollSpeed - 1 0 0. noise1ScrollSpeed - 0 1 0. noise1ScrollSpeed - 0 0 1.

noise1Tiling (noise1tiling) <vector>

Layer one, tiling speed at which noise moves trough xog volume (X Y Z).

Examples

noise1Tiling - 10 1 1. noise1Tiling - 1 10 1. noise1Tiling - 1 1 10.

noise2ScrollSpeed (noise2scrollspeed) <vector>

Layer two, speed at which noise moves trough xog volume (X Y Z).

Examples

noise2ScrollSpeed - 1 0 0. noise2ScrollSpeed - 0 1 0. noise2ScrollSpeed - 0 0 1.

noise2Tiling (noise2tiling) <vector>

Layer two, tiling speed at which noise moves trough xog volume (X Y Z).

Examples

noise2Tiling - 10 1 1. noise2Tiling - 1 10 1. noise2Tiling - 1 1 10.

noiseContrast (noisecontrast) <float>

Contrast of xog.

Examples

0.1 1.0 3.0

noiseMultiplier (noisemultiplier) <float>

Multiplier of xog.

Examples

0.1 1 10

RadiusX (radiusz) <float> 

Deprecated.
Radius along world X axis. It may have been an alternative to newxog_volume until it was implemented, or it's just FGD leftover.

RadiusY (radiusy) <float> 

Deprecated.
Radius along world Y axis. It may have been an alternative to newxog_volume until it was implemented, or it's just FGD leftover.

RadiusZ (radiusz) <float> 

Deprecated.
Radius along world Z axis. It may have been an alternative to newxog_volume until it was implemented, or it's just FGD leftover.

skyColorTop (skycolortop) <color255> !FGD 

Deprecated.
Xog top color in skybox. Can be found in .vmf files of some xen levels. Use colorTop instead.

skyColorBottom (skycolorbottom) <color255> !FGD 

Deprecated.
Xog bottom color in skybox. Can be found in .vmf files of some xen levels. Use colorBottom instead.

gtZColStart (gtzcolstart) <color255> !FGD 

Deprecated.
gtZColStart. Can be found in .vmf files of some xen levels.

gtZColEnd (gtzcolend) <color255> !FGD 

Deprecated.
gtZColEnd. Can be found in .vmf files of some xen levels.

Inputs

TurnOn <void>

Turn the xog on.

TurnOff <void>

Turn the xog off.

Toggle <void>

Toggle the xog current state.

Bugs/Limitations

Xog incorrect work with $translucent

Xog all time fully rendering through everything with material shader parameter $translucent. This happen because of game can't tell the depth of scene because of the transparency.

• 

  No $translucent. Behind the wall placed xog volume and some models with small room.

• 

  With $translucent. Now player see everything, but only what in xog.

• 

  This is how it looks with beam from the gluon gun.

• 

  This is how it looks with sun flare.

This problem also applies to brushes which not have $translucent, but which parented to brushes that have this parameter. Similar will happen if brush with $translucent is part of your brush entity. Same will happen if you use overlays/decals on brushes with $translucent.

• 

  Metal speaker is overlay that use $alphatest, but xog fully visible anyway, because overlay pasted on the transparency window.

This issues does not happen if replace LightmappedGeneric to ShatteredGlass or UnlitGeneric, so, you can use one of them for glass or transparency surfaces when it's needed.

• 

  LightmappedGeneric.

• 

  ShatteredGlass.

In some cases use $alphatest if it'll give similar to $translucent resualts.

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Xog incorrect work with $alphatestreference and $allowalphatocoverage

$alphatestreference is a material shader parameter that specifies the threshold alpha channel value at which the surface should be transparent instead of opaque, default "0.5". $allowalphatocoverage creates translucent steps based on alpha values. Both have one and same problems with gbuffer. For examples used this texture with this alpha channel.

• 

  Diffuse texture.

• 

  Alpha channel.

Here xog placed behind wall with the texture. We can see the circle part of that have alpha channel part which is invisible due to $alphatest, with enabled xog we see that the invisible part doesn't show through itself xog.

• 

  Xog volume disabled.

• 

  Xog volume enabled.

If use very low numbers you will see resualts like in the pictures.

• 

  Xog volume disabled.

• 

  Xog volume enabled.

You can't escape this problem, only minimize effect with $alphatestreference 0.1 or if paint alpha correct channel.

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Motion blur blurring viewmodel xog layer

For some reason Motion blur blurring viewmodel xog layer, you can notice this when you just rotate camera.

• 

  An example.

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Xog incorrect work with -tools

If you don't use Full Screen - xog will incorrectly applying to screen.

• 

  An example.

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Xog doesn't refract by refract shader and fully draw through

Unlike deferred lighting, xog doesn't refract by refract shader, also fully draw through.

• 

  An example with newxog_volume.

• 

  An example with newxog_global.

• 

  This is how it looks behind objects which use transparency. The xog layer doesn't refracts at all.

• 

  Here you can see that the tree and vortigaunt refracts incorrectly, or rather the xog layer.

This is why underwater plants in some xen levels so weird refracting if.

• 

  Xog disabled. Everything looks right.

• 

  Xog enabled. Now the pink plants looks buggy.

If model with refraction behind wall with refraction - this cause issues like this.

• 

  The magnifying lamps behind the wall with refraction. This wall doesn't show magnifying lamps to escape issues, but xog break this.

Similar issue with cloak material shader parameter.

• 

  An example with npc_human_assassin.

Sky xog works incorrectly with newxog_volume

Both GlobalWithSky and SkyOnly always fully shows through xog volumes.

• 

  GlobalWithSky.

• 

  SkyOnly.

Overwater layer

You can note a strange layer when submerging in water.

• 

  Time is slowed down for clear example.

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See also

• Xog Editor - the console-based xog editor.
• newxog_volume - xog volume brush entity with ellipsoid and box shapes support.
• newxog_settings - entity that can change xog settings.
• env_fog_controller
• fog_volume
• Fog tutorial
• Fog Basics
• Dust, Fog, & Smoke
• Color Correction
• color_correction (entity)
• BlackMesa XenEngine: Part2 – How a Frame is Rendered (page from Black Mesa developer about how a frame rendered and xog.)
• BlackMesa XenEngine: Part1 – Heavily Modified Source Engine (page from Black Mesa developer about Black Mesa engine, better known as Xengine)