Newxog volume

newxog_volume is a brush entity available in Black Mesa. This is xog (Xen Fog) volume, brush entity that creates a fog transition, making spaces appear deeper than they are.

Class hierarchy
CNewXogVolume ↳CBaseTrigger ↳CBaseToggle ↳CBaseEntity

Xog volume example.

The texture that use level designers to mark this entity.

Note:This entity have trigger_once functions but they are not in FGD and never work.

Tip:Use tools/tools_xogvolume texture for your xog volumes to quickly distinguish them from triggers while level creation.

Tip:In addition to using this entity as a fog in certain areas, it is also great for use for func_water_analog, since func_water_analog haven't itown fog in it's volume.

Important:This entity doesn't affects optimization, this entity for visual effects only.

Important:This brush entity uses bbox brush volume to render and not brush volume itself.

An example.

Xog brush volume in Hammer. Xog in the game.

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

Shape Type (xogtype) <choices>

Shape type to use. You can use BBOX or Ellipsoid.

• 0:0: LocalVolume BBOX
• 1:1: LocalVolume Ellipsoid

Examples

BBOX Ellipsoid

colorMode (colormode) <choices>

This is FGD leftover from newxog_global. This feature doesn't work for this entity.

Texture name Grad Texture (texname) <string>

This is FGD leftover from newxog_global. This feature doesn't work for this entity.

colorTop (colortop) <color255>

Xog top color. This is the main color of xog that uses if Enable Height Blend property is disabled.

Examples

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

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

colorBottom (colorbottom) <color255>

Xog bottom color. Requires enabled Enable Height Blend to be working.

Examples

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

distStart (diststart) <float>

distStart

Xog start draw distance.

Examples

distStart - 10. distEnd - 100. distStart - 70. distEnd - 100. distStart - 200. distEnd - 100.

Bug:Numbers lower than 1 cause xog graphics issues.

Bug examples

Black Mesa - bm_c1a2c. As you can see, the fog is drawn through the geometry and models (with exception of viewmodel). Black Mesa - bm_c1a2c. As you can see, the fog is drawn through the geometry and models (with exception of viewmodel).

distEnd (distend) <float>

distEnd

Xog end draw distance.

Examples

distStart - 10. distEnd - 100. distStart - 10. distEnd - 700. distStart - 10. distEnd - 2000.

Bug:Numbers lower than 1 cause xog graphics issues.

Bug examples

Black Mesa - bm_c1a2c. As you can see, the fog is drawn through the geometry and models (with exception of viewmodel). Black Mesa - bm_c1a2c. As you can see, the fog is drawn through the geometry and models (with exception of viewmodel).

Note:The difference in values of distStart and distEnd should be not too big, otherwise the fog will be unsmooth.

distDensity (distdensity) <float>

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

Examples

0 1

opacityOffsetTop (opacityoffsettop) <float>

Offsets top color of xog.

Examples

opacityOffsetTop - 0.0. opacityOffsetTop - 0.5. opacityOffsetTop - 2.0.

opacityOffsetBottom (opacityoffsetbottom) <float>

Offsets bottom color of xog.

Examples

opacityOffsetBottom - 0.0. opacityOffsetBottom - 0.2. opacityOffsetBottom - 1.0.

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 through 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 through 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 through 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

Enable Height Blend (enablevol_height) <choices>

Determines bottom color and blending is disabled or enabled.

• 0: Disabled
• 1: Enabled

Examples

Enable Height Blend - No. colorTop - 255 0 0 255, colorBottom - 0 255 0 255. Enable Height Blend - Yes. colorTop - 255 0 0 255, colorBottom - 0 255 0 255.

Inputs

TurnOn <void>

Turn xog on.

TurnOff <void>

Turn xog off.

Toggle <void>

Toggle the xog between on and off stages.

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.

Similar issue happen if use $alphatestreference incorrectly.
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.

---

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.

---

Motion blur blurring viewmodel xog layer

For some reason Motion blur blurring viewmodel xog layer, you can notice this when you just rotate camera. This issue happen even if xog behind other objects.

• 

  An example.

---

Xog incorrect work with -tools

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

• 

  An example.

---

Xog volume doesn't work with 3D Skybox

Don't use xog volumes in your 3D skyboxes, none of them will work at all.

• 

  An example. We see that xog volume works fine, but 3D Skybox don't draw it.

---

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.

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.

---

See also

• Xog Editor - the console-based xog editor.
• newxog_global - global xog, similar to env_fog_controller.
• 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)