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Breakable surf.jpg

func_breakable_surf is a brush entity available in all Source games. It defines a breakable surface, for partially breakable glass/tile/etc. All faces that are not ever visible to the player should use nodraw. Faces that will be broken must have exactly four sides. The material applied to the visible face must be set up to be breakable.

Note:Despite common misconception, this entity is available and functional in <Team Fortress 2>, although without sounds.

The following standard textures are meant to work with this entity (using any other may crash the game on startup!):

  • glass/glasswindowbreak070a (but not glass/glasswindowbreak070b!)
  • tile/tilebreak001c (using this will stretch the texture if broken)
  • glass/urban_glass_3 (New with Counter-Strike: Global Offensive)

To do: What does a material need in order to work correctly?

Bug: Using Tile as the Surface Type in Half-Life 2 will show missing textures and make the whole surface non-solid when damaged.
Bug: The break sound will play from both the entity and the origin of the map (0,0,0), if this entity is placed on the boundary of the default visleaf cuts (indicated by blue lines in Hammer 2D view).


  • 1: Physics damage decals
  • 2: Take damage from held objects
Note:The 1 and 2 flags listed below (from CBreakable) do not apply to this entity! CBreakableSurface overrides them.

Breakable (brush):

  • 1: Only Break on Trigger
  • 2: Break on Touch
  • 4: Break on Pressure
  • 512: Break immediately on Physics
  • 1024: Don't take physics damage
  • 2048: Don't allow bullet penetration


Fragility (fragility) <integer>
If the 'Surface Type' is set to Glass, this value sets how fragile the glass pieces are after the surface has been broken.
Surface Type (surfacetype) <choices>
Surface material type
  • 0: Glass
  • 1: Tile
error <choices> !FGD
Set automatically by Hammer to indicate an invalid glass/tile surface, when non-zero the entity will be removed when spawned, and a error message will be thrown in the console. This keyvalue is not included in Valve's FGDs, but is still fully functional.
  • 0: No Error
  • 1: Multiple Textured Faces
Note:You must use tools/toolsnodraw to no draw the 5 remaining sides, or otherwise this error will be thrown!
  • 2: Non-Square Face

Breakable (brush):

Prop Data (propdata) <choices>
Set to the best approximation of the size and material of this entity's brushes. If set, this will override Strength and Material Type. If set, it will override this entity's health and damage taken from various weapons. See prop_data base types for what each entry specifies.
Note:Some settings can make the brush unbreakable.
  • 0: None
  • 1: Wooden.Tiny
  • 2: Wooden.Small
  • 3: Wooden.Medium
  • 4: Wooden.Large
  • 5: Wooden.Huge
  • 6: Metal.Small
  • 7: Metal.Medium
  • 8: Metal.Large
  • 9: Cardboard.Small
  • 10: Cardboard.Medium
  • 11: Cardboard.Large
  • 12: Stone.Small
  • 13: Stone.Medium
  • 14: Stone.Large
  • 15: Stone.Huge
  • 16: Glass.Small
  • 17: Plastic.Small
  • 18: Plastic.Medium
  • 19: Plastic.Large
  • 20: Pottery.Small
  • 21: Pottery.Medium
  • 22: Pottery.Large
  • 23: Pottery.Huge
  • 24: Glass.Window
Strength/Health (health) <integer>
The damage to take before breaking. The brush will not break from damage if this is 0.
Material Type (material) <choices>
Set to the material type of the brush. Decides what sounds to make when damaged, and what gibs to produce when broken.
  • 0: Glass - As stated, uses glass gibs and sounds. Gibs may not match with material used.
  • 1: Wood - As stated, uses wood gibs and sounds. Gibs may not match with material used, and may be too big for certain brushes.
  • 2: Metal - As stated, uses metal gibs and sounds. Gibs are very small, and evidently made for vents. May not match material.
  • 3: Flesh - Uses HL1 gib death sounds and wood gibs. Not much practicality for this type unless one is making a meat slab (With proper gibs, of course).
  • 4: CinderBlock - Uses concrete gibs and sounds. Gibs may not match with material and be too big for the brush.
  • 5: Ceiling Tile - Uses tile sounds, wood gibs and HL1 plaster gib death sound.
  • 6: Computer - Uses spark sounds and wood gibs, coupled with an HL1 gib death sound.
  • 7: Unbreakable Glass - Uses glass sounds. Using this material type overrides any Strength value previously set to 0, making it unbreakable.
  • 8: Rocks - Uses concrete gibs and sounds. Gibs may not match with material, and don't even look like rocks to begin with.
  • 9: Web !FGD - Only functional in Half Life Source.
  • 10: None
Gibs Direction (explosion) <choices>
Used to decide which direction to throw gibs when broken.
  • 0: Random
  • 1: Relative to Attack
  • 2: Use Precise Gib Dir (see below)
Precise Gib Direction (gibdir) <angle>
An exact direction in which to throw gibs when breaking. Be sure to select "Use Precise Gib Dir" in Gibs Direction!
Damaging it Doesn't Push It (nodamageforces) <boolean>
When enabled the brush will move in response to damage.
Gib Model (gibmodel) <string>
Used by HL1Port to specify a custom gib model to break into, overriding the Material Type.
Spawn On Break (spawnobject) <choices>
When broken, an entity of the selected type will be created.
Note:Only these entities may be spawned. This can be fixed by modifying func_break.cpp.
  1. item_battery
  2. item_healthkit
  3. item_ammo_pistol
  4. item_ammo_pistol_large
  5. item_ammo_smg1
  6. item_ammo_smg1_large
  7. item_ammo_ar2
  8. item_ammo_ar2_large
  9. item_box_buckshot
  10. item_flare_round
  11. item_box_flare_rounds
  12. item_ml_grenade
  13. item_smg1_grenade (unusable!)
  14. item_box_sniper_rounds
  15. Unused
  16. weapon_stunstick
  17. weapon_ar1 (unusable!)
  18. weapon_ar2
  19. Unused
  20. weapon_ml
  21. weapon_smg1
  22. weapon_smg2 (unusable!)
  23. weapon_slam (unusable!)[Why?]
  24. weapon_shotgun
  25. weapon_molotov (unusable!)
  26. item_dynamic_resupply
Explode Magnitude (explodemagnitude) <integer>
If non-zero, when this entity breaks it will create an explosion that causes the specified amount of damage.
Confirm:Damage radius is proportional to magnitude.
Dead model (deadmodel) <model> !FGD
Deprecated. Purpose unknown. Does absolutely nothing inside code.
Shards (shards)  !FGD
Deprecated. Purpose unknown. Does absolutely nothing inside code.
Lip (lip)  !FGD
Deprecated. Purpose unknown. Does absolutely nothing inside code.

Breakable (common):

Performance Mode (PerformanceMode) <choices>
Used to limit the amount of gibs produced when this entity breaks, for performance reasons.
  • 0: Normal
  • 1: No Gibs
  • 2: Full Gibs on All Platforms (Xbox 360, PS3, etc)
  • 3: Reduced gibs
Min Damage to Hurt (minhealthdmg) <integer>
If a single hit to the object doesn't do at least this much damage, the prop won't take any of the damage it attempted to give.
Pressure Delay (PressureDelay) <float>
Seconds to delay breaking from pressure. Allows creaking/groaning sounds to play.
Health (health) <integer>
How close to breaking the object is.
Maximum Health (max_health) <integer>
Health cannot exceed this amount.
Physics Impact Damage Scale (physdamagescale) <float>
Multiplier for damage amount when this entity is hit by a physics object. With a value of 0 the entity will take no damage from physics.
Breakable By (BreakableType) <choices> (New with Left 4 Dead)
<Left 4 Dead><Left 4 Dead 2> only. Who can break this?
  • 0: Everyone
  • 1: All Infected
  • 2: Only Tanks

Visible Brush:

Minimum Light (_minlight) <float>
Minimum amount of light to hit this brush. 0 is none, 1 is normal, and 2 is doubled.
Damage Filter Name (damagefilter) <targetname>
When this entity receives damage, it will filter by this entity.
Render Mode (rendermode) <choices>
Set a non-standard rendering mode on this entity.
Render FX (renderfx) <choices>
Preset pattern of appearance effects.
To do: 18-21, 25
Render FX / Transparency (0 - 255) (renderamt) <integer>
Transparency amount, requires a Render Mode other than Normal. 0 is invisible, 255 is fully visible.
Render Color (R G B) (rendercolor) <color255>
Color tint.
Shadow Cast Distance (shadowcastdist) <integer> !FGD
Sets how far the entity casts dynamic shadows. 0 means default distance from the shadow_control entity.
Shadows (vrad_brush_cast_shadows) <integer> !FGD
Determines if this entity will cast lightmap shadows.
  • 0: No shadows
  • 1: Cast shadows
Disable Shadows (disableshadows) <boolean>
Prevent the entity from creating cheap render-to-texture shadows. Does not affect shadow mapping.
Disable Receiving Shadows (disablereceiveshadows) <boolean>
Prevent the entity from receiving shadows on itself.
Texture Frame (texframeindex) <integer> !FGD
The frame number for any animated textures on this entity.
Minimum CPU Level (mincpulevel) <choices> (New with Left 4 Dead)
A user with a CPU level lower than this will not see this object rendered in-game. It's unclear how the CPU level is decided, but most systems are classified as "high".
Maximum CPU Level (maxcpulevel) <choices> (New with Left 4 Dead)
  • 0: Default
  • 1: Low
  • 2: Medium
  • 3: High
Minimum GPU Level (mingpulevel) <choices> (New with Left 4 Dead)
Maximum GPU Level (maxgpulevel) <choices> (New with Left 4 Dead)
  • 0: Default
  • 1: Very low
  • 2: Low
  • 3: Medium
  • 4: High


Minimum Bounding Box Size (mins) <vector> !FGD
Co-ordinate of the minimum bounding box corner. The bounding box is drawn from this corner to the other one. Requires Bounding Box collisions (solid 2) to be used. Can be used to overwrite the collision shape of a brush, although it can only be a cuboid.
Maximum Bounding Box Size (maxs) <vector> !FGD
Co-ordinate of the maximum bounding box corner. The bounding box is drawn from this corner to the other one. Requires Bounding Box collisions (solid 2) to be used. Can be used to overwrite the collision shape of a brush, although it can only be a cuboid.
Collisions (solid) <choices> !FGD
Method of collision for this entity.
Model Index (modelindex) <short> !FGD
Changes the entity's model to a precached model on the map.


Classname (classname) <string>
The classname defines the type of entity. Classnames can be changed using AddOutput, which will influence how the engine deals with the entity in certain circumstances.
Name (targetname) <string>
The name that other entities refer to this entity by.
Global Entity Name (globalname) <string>
Name by which this entity is linked to another entity in a different map. When the player transitions to a new map, entities in the new map with globalnames matching entities in the previous map will have the previous map's state copied over their state.
Parent (parentname) <targetname>
Specifies a movement parent. An entity will maintain its initial offset from its parent. An attachment point can be added to the end of the name, separated by a comma. Every entity can be parented, even point entities. Entities which are parented will be forced to transition to the next map, such as from a trigger_transition. Some entities which aren't intended to be parented may not function correctly. phys_constraint can be used as a workaround to parenting.
Origin (X Y Z) (origin) <coordinates>
The position of this entity's center in the world. Rotating entities typically rotate around their origin.
Pitch Yaw Roll (X Y Z) (angles) <angle>
This entity's orientation in the world. Pitch is rotation around the Y axis, yaw is the rotation around the Z axis, roll is the rotation around the X axis.
Note:This works on brush entities, although Hammer doesn't show the new angles.
Flags (spawnflags) <integer>
Toggles features of an entity, its specific number is determined by the combination of flags added.
Response Contexts (ResponseContext) <string>
Pre-defined response system contexts for this entity. Format is key:value,key:value,.... Contexts may be filtered.
Effects (effects) <integer> !FGD
Combination of effect flags to use.
Local Time (ltime) <float> !FGD
The local time of the entity, independent of the global clock. Used mainly for physics calculations.
Next Think (nextthink) <float> !FGD
Amount of time before the entity thinks again.
Hammer ID (hammerid) <integer> !FGD
The entity's Hammer ID. Mainly used by plugins and debugging commands, such as ent_keyvalue. Can be manually assigned with the "hammerid" or "id" keyvalue. Entities spawned at run-time are not assigned any Hammer ID.
Disable for Xbox 360 (disableX360) <boolean> (New with Left 4 Dead 2) !FGD
If Yes, disables this entity on the Xbox 360 version of Source.
Entity Scripts (vscripts) <scriptlist> (New with Left 4 Dead 2)
Space delimited list of VScript files (without file extension) that are executed after all entities have spawned. The scripts are all executed in the same script scope, later ones overwriting any identical variables and functions.
Script think function (thinkfunction) <string> (New with Left 4 Dead 2)
Name of a function in this entity's script which will be called automatically every 100 milliseconds (ten times a second) for the duration of the script. It can be used to create timers or to simulate autonomous behavior. The return value (if present) will set the time until the next call. Try to avoid expensive operations in this function, as it may cause performance problems.
Lag Compensation (LagCompensate) <boolean> (New with Left 4 Dead 2) !FGD
Set to Yes to lag compensate this entity. Should be used very sparingly!
Is Automatic-Aim Target (is_autoaim_target) <boolean> (New with Counter-Strike: Global Offensive) !FGD
If set to 1, this entity will slow down aiming movement for consoles and joystick controllers when the entity is under the crosshairs.


Shatter  <vector>
Shatter the window. Input a vector. First two coordinates are the X,Y center of the shattering (as values from 0-1). The third coordinate is the radius of the shatter, in hammer units.

Breakable (brush):

SetMass  <float>
Damaging the entity applies physics forces to it.


Breaks the breakable.
SetHealth  <integer>
Sets a new value for the breakable's health. If the breakable's health reaches zero it will break.
AddHealth  <integer>
Adds health to the breakable.
RemoveHealth  <integer>
Removes health from the breakable.

Visible Brush:

Alpha  <integer>
Sets the entity's transparency to a number from 0 (invisible) to 255 (fully visible). Requires the entity to have its Render Mode (rendermode) set to a number other than 0.
AlternativeSorting  <boolean>
Swaps the rendering order of the entity. Used to attempt to fix sorting problems when rendering, for example an object rendering in front of translucent materials.
Color  <color255>
Sets an RGB color for the entity.
SetDamageFilter  <targetname>
Sets a filter for this entity for when it receives damage.
Allows the entity to be pushed by damage done to it (usually force amount correlates with the damage done).
Prevents the entity from being pushed by damage done to it.
Allows the entity to draw a render target shadow.
Prevents the entity from drawing a render target shadow.
EnableDraw  (New with Portal 2)
Removes EF_NODRAW from the entity.
DisableDraw  (New with Portal 2)
Applies EF_NODRAW to the entity. Note that this is different than rendermode 10.
EnableReceivingFlashlight  (New with Portal 2)
Makes it so that the entity is lit by env_projectedtextures.
DisableReceivingFlashlight  (New with Portal 2)
Prevents the entity from being lit by env_projectedtextures. The shadow made by the texture will still cast.
EnableDrawInFastReflection  (New with Portal 2)
Makes the entity be rendered in reflections from water materials using $reflectonlymarkedentities.
DisableDrawInFastReflection  (New with Portal 2)
Prevents the entity from rendering in fast reflections.


Removes this entity and any entities parented to it from the world.
Functions the same as Kill, although this entity and any entities parented to it are killed on the same frame.
SetParent  <string>
Move with this entity. See Entity Hierarchy (parenting).
SetParentAttachment  <string>
Change this entity to attach to a specific attachment point on its parent. The entity will teleport so that the position of its root bone matches that of the attachment. Entities must be parented before being sent this input.
SetParentAttachmentMaintainOffset  <string>
As above, but without teleporting. The entity retains its position relative to the attachment at the time of the input being received.
Removes this entity from the the movement hierarchy, leaving it free to move independently.
AddOutput  <string>
Evaluates a keyvalue/output on this entity.
Format: <key> <value>
Format: <output name> <targetname>:<inputname>:<parameter>:<delay>:<max times to fire, -1 means infinite>
FireUser1 to FireUser4
Fire the OnUser outputs; see User Inputs and Outputs.
Use  !FGD
Same as a player invoking +use; may not do anything. Can also be invoked by creating an output that does not specify an input.
This input is not included in Valve's FGDs.
DispatchEffect  <string> !FGD
Dispatches a special effect from the entity's origin. Removed and replaced entirely by the particle system since <Left 4 Dead>.
DispatchResponse  <string> !FGD
Dispatches a response to the entity. See Response and Concept.
AddContext  <string>
Adds to the entity's list of response contexts. Format is <key>:<value>.
RemoveContext  <string>
Remove a context from this entity's list. The name should match the key of an existing context.
ClearContext  <string>
Removes all contexts from this entity's list.
RunScriptFile  <script> (New with Left 4 Dead 2)
Execute a VScript file from disk, without file extension. The script contents are merged with the script scope of the receiving entity.
RunScriptCode  <string> (New with Left 4 Dead 2)
Execute a string of VScript source code in the scope of the entity receiving the input. String quotation may be needed when fired via console.
Bug:  In <Left 4 Dead 2>, the code is executed in the script scope of the entity that fires the output, not the one receiving the input.
Warning: Never try to pass string parameters to a script function with this input. It will corrupt the VMF structure because of the nested quotation marks, which then must be removed manually with a text editor.
CallScriptFunction  <string> (New with Left 4 Dead 2) !FGD
Execute a VScript function in the scope of the receiving entity.
SetLocalOrigin  <coordinates> (New with Portal 2) !FGD
Send this entity to a spot in the map. If the entity is parented to something, it will be offset from the parent by this amount.
SetLocalAngles  <angles> (New with Portal 2) !FGD
Set this entity's angles.


Breakable (common):

Fired when this object breaks. !activator is whatever breaks the object.
OnHealthChanged  <float>
Fired whenever the health of the breakable has increased or decreased. This output automatically puts the new health amount as a decimal percent (e.g. 45% = 0.45) into the parameter box for inputs, if the mapper does not override the parameter with something else.


OnUser1 to OnUser4
These outputs each fire in response to the firing of the like-numbered FireUser1 to FireUser4 Input; see User Inputs and Outputs.
OnKilled  (New with Left 4 Dead)
This output fires when the entity is killed and removed from the game. <Left 4 Dead> only.

See Also