prop_data base types
Every Model that is to be used by prop_physics (and some that are to be used by prop_dynamic) must have a prop_data
block. The block is embedded with the QC command $keyvalues
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Breakable Brush propdata is configured via the relevant Entity Properties : see func_physbox, func_breakable_surf, func_breakable.
prop_data
co-exists with, but is distinct from, $surfaceprop
.

prop_data
cannot be prop_static.Should my model be physical?
In Half-Life 2, Valve tried to follow these general rules:
- If it's going to attach to or act as a support for a non-moving thing...
- It should be static.
- If it generates light...
- It should be static.
- If it's really big and the player couldn't possibly move it...
- It should be static.
- Otherwise...
- It should be physical.
QC syntax example
$keyvalues { prop_data { base Wooden.Small dmg.bullets 0 explosive_damage 100 explosive_radius 50 } }
- This example derives all its prop_data from the generic base_type "Wooden.Small".
- It then uses additional keyvalues to modify 3 special characteristics only for this model.
- So this particular small, wooden model will be bulletproof, but when it breaks it will explode, causing up to 100 damage to entities within a 50 unit radius.
Tips
- You don't need to override anything at all if you don't want to
- Just set a
base
and you've got a working physics prop. - Don't override health levels in all your props
- Instead, use the base_types and let them set the health. This way you won't have one chair that takes twice as much damage as every other chair.
- Whenever possible, avoid mixing material types inside the same prop
- Don't make half-metal, half-wood props.
- Follow Valve's rules above unless you have good reason to change them
- In addition: Valve consider metal and plastic invulnerable, but everything else breakable.
- Avoid collecting multiple objects into the same prop
- Especially if you or Valve individually simulate identical-looking objects elsewhere.
- Avoid moving parts and materials Source doesn't simulate
- Don't hang coats from a coat rack or put water in a physical fish tank.
Options
General
base
<base_type>- Defines the physical properties of the prop, according to the material from which it is made. All other keyvalues override those inherited from this!
- See prop_data base material guidelines for a list of the stock prop_data base_types from Source SDK Base.
health
<integer>- The amount of damage this prop should take before breaking.

allowstatic
<boolean>- Allow this model to be prop_static as well as prop_physics. For consistency, avoid using this.
physicsmode
<choices>- Sets the physics mode used by prop_physics_multiplayer.
Number | Name | Description |
---|---|---|
1 | Solid, Server-side | Solid, pushes the player away. |
2 | Non-Solid, Server-side | Non-solid, but gets pushed away by the player. |
3 | Non-Solid, Client-side | Non-solid, clientside simulated only. |
blockLOS
<boolean>- Overrides whether the prop should block NPC Line of Sight. If unspecified, the game engine will decide based on the model's dimensions.
AIWalkable
<boolean>- Set whether AI should try walking over this prop. Todo: Does the prop type matter?
Damage modifiers
Use damage modifiers to reflect differences between the amount of damage that an object takes from different attacks. Don't use them to reflect overall damage strength. (e.g. Stone is resilient to everything. To reflect this, increase the health of all stone objects, don't set the damage modifiers lower.)
dmg.bullets
<float>- Modifies damage done by bullets. Default is 1.0
- Paper, Cloth and Glass.Window base_types = 0.5
- Wooden base_types = 0.75
- Flesh = base_types 1.25.
dmg.club
<float>- Modifies damage done by blunt impacts. Default is 1.0
- Cloth base_types = 0.75
- Paper and Pottery base_types = 1.25
- Wooden base_types = 2.0
dmg.explosive
<float>- Modifies damage done by explosions. Default is 1.0
- Paper, Cloth, Pottery, Flesh and Wooden base_types = 1.5
damage_table
<choices>- Impact Damage Tables are defined in C++ code (in physics_impact_damage.cpp), and contain very detailed information about what damage a prop should take from different directions and forces. Only Glass and Pottery base_types inherit one.
Tip:Use
damage_table ""
to ignore an inherited table.
Flammable props
fire_interactions is a sub-set of the prop_data $keyvalues that defines flammability. There are only three known parameters, each with only one known value:
$keyvalues { prop_data { fire_interactions { ignite "halfhealth" // Will ignite on reaching 50% health. explosive_resist "yes" // Clamp blast damage so that the prop ignites instead of breaking. flammable "yes" // Can be ignited by fire and explosions. } } }
Exploding props
If these two fields are specified for a prop, then the prop will create an explosion with the specified values when it breaks.
$keyvalues { prop_data { health 1 // health must be >0 for the prop to be breakable. explosive_damage <float> // The amount of explosive damage done by this prop when it breaks. explosive_radius <float> // The radius of the explosion caused by this prop when it breaks. } }
Gibs
The prop_data system handles generic gibs. Generic gibs are used for any breakable object that doesn't have custom gibs. Custom gibs are assigned to a model using the $collisiontext QC command.
- breakable_model <choices>
- Defines the set of generic gibs this prop should break into.
- WoodChunks
- GlassChunks
- ConcreteChunks
- MetalChunks
- Only props with the Wooden base_type inherit a gibset (WoodChunks).
- This is only necessary if the prop doesn't have custom gibs. In general custom gibs are far superior to generic ones, but of course, there's a limit to how many custom gibs you can fit into memory.
- Generic Gibsets are defined at the bottom of
mod/scripts/propdata.txt
. - breakable_count <integer>
- The number of generic breakable gibs to break into. Required for gibs to appear.
- This allows you to hard-code the number gibs yourself. By default the game engine will attempt to attribute a sensible number of generic gib models within the volume of the breaking object, based upon their (and its) size.
- Only props with the Wooden base_type inherit a gib count - ranging from Wood.Tiny = 0 through to Wood.Huge =10.
- breakable_skin <integer>
- The skin to use on the generic breakable models.
- Allows you to specify a skin to use on the gib models, which is useful for matching the original prop's material.
- Only props with Wooden base_types inherit a gib skin (skin 0).
- multiplayer_break <choices>
- Determines whether the gibs from a prop_physics_multiplayer are simulated on the Client or Server or both.
Literal Value | Description |
---|---|
both | Creates gibs on both the server and the client. |
server | Only creates gibs on the server. |
client | Only creates gibs on the client. This is the default behavior. |
- Usually small gibs have no significant collision effect that might influence in-game events, so these are handled clientside rather than using up client-server connection bandwidth.
Generic prop_data
base_types
The purpose of the prop_data base_type is to apply generic, preset prop_data values to physics models. This ensures that in-game physics interactions are reasonably consistent for similar types of objects.
- Wherever possible, models should use one of these base_types instead of defining their own prop_data values. Once you have set a base_type for your model, it is not necessary to specify any other prop_data keyvalues - you have a working physics model.
- This table shows a list of the prop_data base_type names (and some guidance notes) available for Source SDK Base games. (A mod could conceivably use a different or modified list of prop_data base_type names, but this is unlikely.)
These are the prop_data base types available in Source SDK Base, as of April 2008:
Cardboard.Small
- Cardboard / Paper blocks, less than 1ft3
Cardboard.Medium
- Cardboard / Paper blocks, less than 3ft3
Cardboard.Large
- Large Cardboard / Paper blocks (boxes, paper stacks...)
Cloth.Small
- Small / thin cloth objects
Cloth.Medium
- Heavier cloth / leather objects
Cloth.Large
- Large / thick cloth objects (upholstery)
Wooden.Tiny
- Tiny Wooden pieces that should die in one hit
Wooden.Small
- Wooden blocks, less than 1ft3
Wooden.Medium
- Wooden blocks, less than 3ft3
Wooden.Large
- Large wooden blocks, less than 5ft3
Wooden.ExtraLarge
- Extra large wooden objects
Wooden.Huge
- Huge wooden objects (bookcases, wardrobes...)
Stone.Small
- Stone blocks, less than 1ft3
Stone.Medium
- Medium stone blocks, less than 3ft3
Stone.Large
- Large stone blocks, less than 5ft3
Stone.Huge
- Huge stone blocks, greater than 5ft3
Glass.Small
- Glass blocks, less than 1ft3
Glass.Window
- Window panes
Metal.Small
- Small metal blocks, less than 1ft3
Metal.Medium
- Medium metal objects
Metal.Large
- Large metal objects (cars, fridges...)
Plastic.Small
Item.Small
- Plastic blocks, less than 2ft3
Plastic.Medium
Item.Medium
- Plastic blocks, less than 4ft3
Plastic.Large
Item.Large
- Large Plastic objects, or medium objects with mixes of plastic & metal that you still want destructible (computers etc.)
Pottery.Small
- Pottery blocks, less than 2ft3
Pottery.Medium
- Medium pottery objects (flowerpots, plates...)
Pottery.Large
- Large pottery objects
Pottery.Huge
- Huge pottery objects (big ornate vessels)
Flesh.Tiny
- Flesh/fruit that should die in a single hit
Flesh.Small
- Flesh/fruit less than 1ft3
- Before 'overriding', say, the
health
of just one specific "Wooden.Small" model, consider whether it would in fact be more appropriate to change the health of all "Wooden.Small" models in your mod. If so, you will want to edit the "Wooden.Small" values inpropdata.txt
rather than the QC of your model.
editing propdata.txt
The purpose of game_dir/scripts/propdata.txt
is to define generic, preset prop_data for physics models. This ensures that in-game physics interactions are reasonably consistent for similar types of objects.
Editing propdata.txt is an easy way to apply tweaks to the entire set of prop models without having to recompile each mdl. For example, in response to HL2 playtesting, Valve tweaked the overall amount of health for all wooden objects in the game several times.
Whilst it is possible to define new prop_data base_types, or rename existing ones, this would undermine the whole purpose of the propdata.txt file (vis to preserve consistency between physics models) and may render the vast majority of models available for Source games incompatible with your mod. It is therefore recommended that whenever possible, you should only edit the keyvalues of the existing base_types, not their names. Example (section from Source SDK Base/scripts/propdata.txt):
//================================================================================= // PAPER //================================================================================= // Base damage modifiers for paper objects "Cardboard.Base" // DON'T USE THIS FOR A PROP. USE THE NON.BASE ONES. { "dmg.bullets" "0.5" "dmg.club" "1.25" "dmg.explosive" "1.5" } "Cardboard.Small" // Cardboard or Paper blocks, less than 1 foot cubed. eg small cardboard boxes, notepads, newspapers, thin books. { "base" "Cardboard.Base" "health" "10" } "Cardboard.Medium" // Cardboard or Paper blocks, less than 3 foot cubed. eg cardboard boxes. thick books { "base" "Cardboard.Base" "health" "20" } "Cardboard.Large" // Large Cardboard or Paper blocks. i.e. solid cardboard boxes { "base" "Cardboard.Base" "health" "40" }

Generic gibsets
Generic gibsets are also defined at the foot of propdata.txt. There are only four of them : "WoodChunks", "GlassChunks", "ConcreteChunks" and "MetalChunks". Only "WoodChunks" are assigned to a base_type (namely the "Wooden" base_types). However many models will make direct use of these generic gibsets via the prop_data "breakable_model" key.
- Example (section from Source SDK Base/scripts/propdata.txt):
"WoodChunks" // Sorted in order of smallest to largest { "models\Gibs\wood_gib01e.mdl" "1" "models\Gibs\wood_gib01d.mdl" "1" "models\Gibs\wood_gib01c.mdl" "1" "models\Gibs\wood_gib01b.mdl" "1" "models\Gibs\wood_gib01a.mdl" "1" }
Prototyping models
When working on prototypes, or when you don't have modellers handy, it's useful to be able to work around the prop data system's enforcement. To do this, use the prop_physics_override and prop_dynamic_override entities instead of prop_physics and prop_dynamic. A prop_physics_override entity will not remove itself if it is assigned a model that wants to be static (i.e. has no "prop_data" entry in its $keyvalues
.QC section). It will also allow the level designer to set its "health".
The override entities allow you to temporarily use models incorrectly while prototyping, or waiting for a modeller to finish up a new model that has the properties you desire. It is highly recommended that you use Hammer's Entity Report feature to check each of your maps to ensure you have no override entities left when you ship them. Otherwise you may be shipping physics inconsistencies, and players are extremely quick to notice them (the orange bucket won't move when I shoot it on this level, but it did on the previous one).
See also func_physbox for brush-based physics objects.
See also
- prop_static, prop_dynamic, prop_physics - common prop entities.
- Prop Types Overview - an article describing various prop types.
- physgun interactions - another QC $keyvalues block that defines some special interactions between prop_physics models and the physcannon.