Detail props

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Detail props create the foliage in this screenshot from Dear Esther.

Detail props are reflected by water in this Orion screen. Note the far hillside, beyond the fadeout distance.

Detail props blend with static props in Prison Island.

Detail props are cheap, non-solid objects that randomly emit from materials used by brushes and displacements. They fade out at a distance (by default 1200 units, or 4096 in 20th anniversary and May 2025 update), so are only good for small, surface-hugging features like grass and shrubs.

There are two types of detail prop:

Sprite

Two polygons forming a square, covered with a $translucent material. The prop can be configured to rotate so that it always faces the camera, to sway in the breeze (which soon becomes costly), and/or to bend as players brush past. Cannot cross the surface of water.

Model

3D models should be used sparsely, if at all. There is a per-object DirectX overhead that becomes more and more pronounced as the number of models increases, regardless of how many polygons are being drawn.

Confirm:Verify if true:

Bug:In the vanilla shaders, only the first group defined in the .vbsp file will work on LightmappedGeneric; any other group will not be applied to LightmappedGeneric (only WorldVertexTransition). As such, brushes must use the first group of the first detail type defined, and displacements should use WorldVertexTransition.

Code:Stock compilers limit the number of detail props to 65535. This is not an engine limit, and can technically be raised if necessary by modifying a sanity check in AddDetailSpriteToLump from utils/vbsp/detailobjects.cpp. Raising it too high can cause performance issues, however.

Warning:Left 4 Dead 2 has mutually exclusive detail props. You may not be able to mix nature materials because it would show broken detail props. See L4D2 Detail props for more info.

Usage

Types of detail prop cover ("detail types") are defined in a .vbsp script file (in ANSI format).

Detail props are referenced in materials (VMT file) with the %detailtype parameter (e.g. "%detailtype" "grass01").

VBSP then generates detail props on the material randomly when the map is compiled.

Detail props can be placed manually with the prop_detail and prop_detail_sprite entities, but doing so is rare and can be tedious (especially for sprites).

Tip:The default VBSP file is root\detail.vbsp, but you can create your own as long as you remember to change the corresponding worldspawn setting (Map > Map Properties...). See New detail types (below).

Stock detail types

These types are available in Source SDK Base

Type	View
swamp_land_002
grass01
grass02
coastline_grass01
coastline_grass02
coastline_redgrass01
coastline_redgrass02
coastline_redgrass03
citygrass01
redgrass
redgrass_light
short_redgrass
canal_reeds
PerfTest1
lostcoast_grass
lostcoast_grass2

These types are present but rely on unavailable models:

• swamp_land_001
• swamp_water_001
• grassland1
• grassland2
• grassland3
• rocks3
• test
• coast_pebbles
• street_junk

New detail types

Here is a custom .VBSP file. It requires detail shape support. Use this detail texture with it.

detail
{
	forest_floor_01
	{
		density 1600
		GrassTex
		{
			alpha 0
			RoseFlower
			{
				sprite "0 0 83 128 512"
				spritesize "0.5 0.05 7 13"
				spriterandomscale .3
				amount 0.02
				detailorientation 2
				sway 0.2
				upright 1
				maxangle 70
			}
			FernShrub
			{
				sprite "120 0 136 256 512"
				spritesize "0.5 0.05 17 28"
				spriterandomscale .15
				amount 0.03
				sprite_shape tri
				shape_size 0
				sway 0.3
				upright 1
				maxangle 50
			}
			GrassTuft
			{
				sprite "0 199 120 57 512"
				spritesize "0.5 0 20 10"
				spriterandomscale .2
				amount .6
				sprite_shape cross
				sway .1
				maxangle 95
			}
			PinkFlower
			{
				sprite "83 0 38 128 512"
				spritesize "0.5 0 6 18"
				spriterandomscale .1
				amount 0.02
				detailorientation 2
				sway 0.3
				upright 1
				maxangle 70
			}
			LushShrub
			{
				sprite "256 128 172 128 512"
				spritesize "0.5 0 32 21"
				spriterandomscale .3
				amount 0.01
				sprite_shape tri
				shape_size 0.1
				sway 0.1
				maxangle 40
			}
		}
		LeavesTex
		{
			alpha 1
			DriedGrass
			{
				sprite "256 0 92 120 512"
				spritesize "0.5 0 13 17"
				spriterandomscale .15
				amount .3
				sprite_shape cross
				sway .3
				maxangle 95
			}
			GrassTuft
			{
				sprite "0 199 120 57 512"
				spritesize "0.5 0 20 10"
				spriterandomscale .2
				amount .6
				sprite_shape cross
				sway .1
				maxangle 95
			}
			RoseFlower
			{
				sprite "0 0 83 128 512"
				spritesize "0.5 0.05 7 13"
				spriterandomscale .3
				amount 0.02
				detailorientation 2
				sway 0.2
				upright 1
				maxangle 70
			}
		}
	}
}

The syntax is:

detail
{
	<Detail type>
	{
		density <float>

		<Group>
		{
			alpha <normal>

			<Prop>
			{
				<settings>
			}
		}
	}
}

The commands are:

Detail type

The name for use in %detailtype.

density <float>

How frequently to generate detail props on surfaces using this type. The equation is (surface area * density * 0.000001).

Tip:density 1000000 means one detail prop per unit. Values of 1000 to 1500 are generally used.

Group

Even if you are only defining one detail prop, you must create a group. The name doesn't seem to be used anywhere; it's just for reference.

Note:Non-displacement surfaces use only the first detail group!

alpha <normal>

The displacement alpha value on which the current prop group prefers to be generated. Every time a detail prop is generated, VBSP will choose from the group with the closest alpha value to the one at the current location. If alpha is undefined, all groups will appear in all areas.

Prop

Defines a detail prop. Although uniquely named, there is no way to reference an existing prop later on in the .VBSP: it must be redefined every time it's needed. It's still a good idea to use descriptive names, though!

Prop settings

amount <normal>

The proportion of the group that this model (or sprite) will account for. If the amount values of a group add up to less than 1, fewer detail props will be emitted than specified by density.

upright <bool>

If present (with any value), the model will always point directly upwards. If not present, the model will orient itself to the angle of the surface it sits on.

minangle <float>

maxangle <float>

Used to control emission on steep surfaces. Default values for both are 180 (no restriction).

Tip:By setting a high minangle you can target overhangs. 0 is a flat surface, 90 is straight up.

Sprites

sprite <int|X, Y, W, H, VTF width>

The subregion of the map's detail material to use for this prop.

• X/Y are the top-left position
• W/H are the dimensions of the prop in texels
• VTF width is the X-axis resolution of the whole detail texture.
  Bug:In Valve's code any custom texture must be of the same aspect ratio as detail\detailsprites! Get the fix here.

spritesize <normal|U, V> <float|W, H>

The origin (U/V) and size in units (W/H) of the sprite when it is in the world.

spriterandomscale <normal>

The sprite's size will vary from 100% by this degree. A value of 1 means that the sprite could be generated at anything between 0% and 200% of its normal size.

detailOrientation <int>

How the sprite will react to the camera:

• 0: It will not rotate.
• 1: It will rotate around its origin to always face the camera head-on
• 2: It will rotate around its Z-axis only to face the camera. This is the most common setting, as it foreshortens the sprite while keeping it otherwise head-on.

Note:In Counter-Strike: Global Offensive , sprites seem to always use 2, ignoring what is set in the vbsp.

Note:The detail texture will be stretched to a square with the same height as the VTF width. Consider this when setting the Y and H values.

Note:The sprite is rendered inverted in the X-axis

Shapes

sprite_shape tri

sprite_shape cross

Shapes are props where two or three sprites are arranged in a 3D shape. They can be made to sway as if in a breeze, and can bend away from intersecting players.

Note: sprite shapes work with UnlitGeneric and LightmappedGeneric, but not the grass shader

Warning:Shapes place more load on the GPU, while sway places more load on the CPU. Use both as sparingly as possible. (The Dear Esther team have developed GPU-accelerated sway which is faster and more realistic, but their code is unreleased.)

Bug:Shapes are extremely sensitive to shadows being cast onto them. If you encounter a shape completely dark while being lit (by the sun for example), increase the lightmaps value on your displacement surface or avoid using shapes at all.

Note:Detail shapes are only available in some games, such as and the SDK source code. If you try to create shapes in a game without support for them, the detail props will not be created at all.

Tip:To enable shapes in your mod, either compile with SDK_DLL or open \game\client\detailobjectsystem.cpp and remove the #ifdef from line 27.

sprite_shape <choices>

Creates a set of sprites at different angles, allowing for a pseudo-3D effect.

tri

Three sprites sitting equidistant from each other in a triangle formation.

cross

Two sprites which cross over one another in the middle.

sway <normal>

Percentage of cl_detail_max_sway that the prop bends to.

Tip:The prop doesn't need a sprite_shape to sway, but you do need shape support in your game.

shape_angle <float>

sprite_shape tri only. Number of degrees outward at which to angle the individual sprites. Unfortunately it is not possible to angle inward, for some reason! Useful range is 0-45.

shape_size <normal>

sprite_shape tri only. Percentage of the sprites' width to put between them and the centre of the triangle. 0 means that the sprites cross at the prop's origin.

There are several console commands which affect shapes:

cl_detail_avoid_force

Force with which to avoid players.

cl_detail_avoid_radius

Radius around sprite to avoid players.

cl_detail_avoid_recover_speed

How fast to recover position after avoiding players.

cl_detail_max_sway

Amplitude of the detail prop sway.

If you can't find these, then there is no detail shape support.

Models

Remember that models have a performance overhead that sprites do not. Use them only when needed!

Warning:Keep a very low amount of models even if in game performance is alright. They will make the game/mod crash upon building cubemaps, at least those based in SDK 2013. May not occur on modern branches, however.

Good candidates for models are contiguous objects that need to spread out along the ground, like small rocks, fallen branches and ground-covering plants including ivy and brambles. Things that stand upright are better off as sprites or shapes.

model <string>

A model to use; must be $staticprop and UnlitGeneric (ALL skins). Include \models and .mdl in the path.

Code:To allow VertexLitGeneric models, open game\client\detailobjectsystem.cpp and remove the conditional block from CDetailObjectSystem::UnserializeModelDict().

New detail materials

The sample .VBSP's detail texture.

There are a few hoops to jump through when creating new detail sprite materials:

• Leave at least a one-pixel gap between subregions, or you may find parts of one sprite bleeding over into the next.
• The material must use the UnlitGeneric or (only in ) Grass shader. You'll probably want to use the $vertexcolor, $receiveflashlight, $nocull and $translucent or $alphatest parameters.

Note:Detail sprite shapes will suffer from alpha sorting issues if using $translucent. $allowalphatocoverage is not supported for detail sprites.

• Unless you are overwriting detail\detailsprites.vmt, mappers must remember to select the correct material in Map > Map Properties....

Bug:In Valve's code, detail textures at custom locations must be of the same aspect ratio as detail\detailsprites. You can fix this if you are shipping your own binaries.

Blocking detail props

If you do not want to have detail props being generated in a specific area, use func_detail_blocker (in all games since )(also in ). If func_detail_blocker is not available in the target game, a duplicate VMT of the material could be made without the %detailtype parameter.

Utilities

XBLAH's Modding Tool

XBLAH's Modding Tool - Detail Editor.

Can create or edit detail props files (.vbsp). The editor shows a preview of the detail props, showing both sprites and props, and is integrated with the File Explorer to make it really easy to create new detail props. See more.