NAV (file format)
A NAV file is a map specific Navigation Mesh file that defines the walkable space in a level for bots in GoldSrc (CS:CZ) and Source games. They usually reside in <game folder>/maps
and can be integrated into BSPs in some Source games.[Clarify]
Contents
Games
In Counter-Strike: Source and Counter-Strike: Global Offensive, the file is generated automatically when bots are played or being added into a map for the first time on a specific map that doesn't have one.
Nav Mesh file write is open source in Source SDK 2013: https://github.com/ValveSoftware/source-sdk-2013/blob/0d8dceea4310fde5706b3ce1c70609d72a38efdf/mp/src/game/server/nav_file.cpp#L1071
Nav Mesh generation is also open source in Source SDK 2013: https://github.com/ValveSoftware/source-sdk-2013/blob/0d8dceea4310fde5706b3ce1c70609d72a38efdf/sp/src/game/server/nav_generate.cpp#L3399
Left 4 Dead games have extra data per nav-area, as well as in after the nav place directory (null term string + short?), both of which have unknown format.
File format
unsigned int magicNumber; // Magic number to check if the file is a .nav file (little endian 0xFEEDFACE)
unsigned int version; // Version of the .nav file, for example GMod and TF2 has 16
if ( version >= 10 ) {
unsigned int subVersion; // Sub version of the .nav file, for example GMod has 0, TF2 has 2. This is usedt
}
if ( version >= 4 ) {
unsigned int saveBspSize; // Size of source bsp file to verify that the bsp hasn't changed
}
if ( version >= 14 ) {
unsigned char isAnalyzed;
}
if ( version >= 5 ) {
// Callouts. Places data. This is the "Mid", "Banana", etc stuff that is used in this nav mesh
unsigned short count;
for( int i = 0; i < count; ++i ) {
unsigned short len; // length of the name
char name[len]; // The name. Maximum len is 256
}
if ( version > 11 ) {
unsigned char m_hasUnnamedAreas;
}
}
{
// PreLoadAreas( count )
// This is by default is completely unused, it is left for mods to store custom data
// Assuming that the data is per nav area
//for( int i = 0; i < count; ++i ) {
//}
}
unsigned int areaCount; // number of CNavAreas
area_t area[areaCount]; // Area Data
if ( version >= 6 ) {
unsigned int ladderCount; // number of CNavLadders
ladder_t ladders[ladderCount]; // Ladder Data
}
{
// Load Custom Data
// Again, by default this is unused
}
Area
A navigation area is a bounding square in which bots can move.
struct nav_area_t {
unsigned int ID; // Identifier of the navigation area.
union AttributeBitField {
unsigned char; // In NAV versions ≤ 8
unsigned short; // In NAV versions ≤ 12
unsigned int; // In NAV Versions ≥ 13
};
float nwCorner[3]; // North-West corner vector.
float seCorner[3]; // South-East corner vector.
float NorthEastZ; // Z coordinate of North-East corner.
float SouthWestZ; // Z coordinate of South-West corner.
connectionData_t connectionData[4]; // Connection data in NESW (North, East, South, West) order.
unsigned char hidingSpotCount; // Amount of hiding spots.
hidingSpot_t hidingSpots[hidingSpotCount]; // Hiding spot data.
/* Approach spots were removed in NAV version 15.
unsigned char approachSpotCount; // Amount of approach spots
approachSpot_t approachSpotData[approachSpotCount]; // Approach spot data.
*/
unsigned int encounterPathCount; // Amount of encounter paths.
encounterPath_t encounterPaths[encounterPathCount]; // Encounter path data.
unsigned short PlaceID; // ID of place.
// Ladder data stored in order of vertical direction (up then down).
struct ladderIDSequence_t {
unsigned int ladderCount; // Amount of ladder Ids.
unsigned int ladderIDs[ladderCount]; // Ladder IDs
} ladderIDSequence[2];
float EarliestOccupyTimes[2]; // Earliest occupy times for teams.
float LightIntensity[4]; // Light Intensities for each corner.
unsigned int areaBindCount; // Amount of area-binds stored.
nav_area_bind_t areaBindSequence[areaBindCount]; // Sequence of area-binds stored.
unsigned int InheritVisibilityFromAreaID; // Inherit visibility from area.
void* customData; // Game-specific data.
}
Approach Spot
struct approachSpot_t {
uint approachHereId;
uint approachPrevId;
byte approachType;
uint approachNextId;
byte approachHow;
}
Area-bind
Area-binds are a structure type used in nav areas to determine the visibility between the parent area and another navigation area, based on area ID.
struct nav_area_bind_t {
unsigned int target_area_id; // Area ID of area.
unsigned char AttributeBitField; // Attribute flag field that determines the visibility type.
};
Area-binds were added in NAV version 16.
Connection
struct connectionData_t {
unsigned int count; // Amount of connections.
unsigned int AreaIDs[count]; // List of area IDs that each connection points to.
};
Hiding Spot
Hiding spots are data structures used to determine points in a nav mesh that bots can hide at.
enum Attribute : unsigned char // Hiding Spot attribute values.
{
IN_COVER = 0x01, // In a corner with good hard cover nearby
GOOD_SNIPER_SPOT = 0x02, // Had at least one decent sniping corridor
IDEAL_SNIPER_SPOT = 0x04, // Can see either very far, or a large area, or both
EXPOSED = 0x08 // Spot in the open, usually on a ledge or cliff
};
struct hidingSpot_t {
unsigned int ID; // Identifier of hide spot. Added in NAV version 2.
float position[3]; // Position of the hiding spot. Added in NAV version 1.
unsigned char Attributes; // Attribute field. Added in NAV version 2. Defaults to IN_COVER for version 1
};
Game | Used For |
---|---|
Team Fortress 2 | Determines where Spy bots can lurk for targets. |
Counter-Strike: Source | Determines where bots can take cover and shoot at. |
Counter-Strike: Global Offensive | Determines where bots can take cover and shoot at. |
Encounter Path
Encounter paths are structures used to determine routes to take to get to certain areas.
struct encounterPath_t {
unsigned int EntryAreaID; // ID of the Area entered from.
unsigned byte EntryDirection; // Direction of entry.
unsigned int DestAreaID; // ID of the Area destination.
unsigned byte DestDirection; // Direction towards the destination area.
unsigned char encounterSpotCount; // Amount of encounter spots.
encounterSpot_t encounterSpots[encounterSpotCount]; // Encounter spots.
};
Encounter Spot
Encounter Spots (better termed waypoints) are data structures used in encounter paths to determine the order of area IDs in a route.
struct encounterSpot_t {
unsigned int AreaID; // The Area ID to go to.
unsigned char ParametricDistance; // Parametric distance in bytes.
};
Ladder
A navigation mesh ladder.
struct nav_ladder_t {
unsigned int ID; // Identifier of the navigation ladder.
float width; // extent of ladder
float top[3]; // top endpoint of ladder
float bottom[3]; // bottom endpoint of ladder
float length; // ladder length
unsigned int direction; // Direction of the ladder (NavDirType)
unsigned char bDangling; // if version 6, dangling status
unsigned int topForwardArea; // area ID
unsigned int topLeftArea; // area ID
unsigned int topRightArea; // area ID
unsigned int topBehindArea; // area ID
unsigned int bottomArea; // area ID
}
Custom Data
Some games store custom data in areas.
Subversion | Data | Label |
---|---|---|
2 | unsigned int | Team Fortress 2 specific attributes. |
1 | char[14] | Counter-Strike: Global Offensive unknown data. |
Versions Used By Games
Game | Version | Subversion |
---|---|---|
Team Fortress 2 | 16 | 2 |
Garry's Mod | 16 | 0 |
Left 4 Dead 2 | 16 | 14 |
Left 4 Dead | 15 | 13 |
Counter-Strike: Source | 9 | n/a |
Counter-Strike: Condition Zero | 5 | n/a |
See also
NAV processors
- Nav file parser in C++.
- libSourceNav — a NAV parser in Common Lisp.
- Base NAV file format in Kaitai Struct.
- Nav file parser in Go. (Outdated)