Paths (GTA IV)

Paths in Grand Theft Auto IV are similar to the 64 node-files introduced with GTA San Andreas. Like the first version of the format there are 64 node files where each file corresponds to a 750x750 square unit starting with  in the south-west corner (-3000.0, -3000.0) and ending in the north-east corner (3000.0, 3000.0) of the game's world in row-major order.

Preamble
Before trying to understand the format of GTA IV's path files, it is recommended to read the GTA San Andreas paths article, since GTA IV paths are an update of the old format.

Unlike San Andreas, paths are not stored in the major archive file (gta3.img) and the node files also do not have the extension  anymore. In GTA IV, paths are stored in the  file as 64   files. Furthermore the file structure has generally changed: If San Andreas had 7 sections per node file, GTA IV only has 2. Linking works in a different way and there are no navi nodes any longer.

File Format
The following data types and structures are used within this article:
 * INT8/UINT8 - signed/unsigned 8 bit integer (1 byte)
 * INT16/UINT16 - signed/unsigned 16 bit integer (2 byte)
 * INT32/UINT32 - signed/unsigned 32 bit integer (4 byte)
 * FLOAT - single precision floating point number (4 byte)

Header
The header is a structure of 4 values with a size of 16 bytes.

4b - UINT32 - Number of nodes (section 1) 4b - UINT32 - Number of car-nodes 4b - UINT32 - Number of intersection nodes 4b - UINT32 - Number of links (section 2)

Section 1 - Nodes
4b - UINT32 - MemAddress 4b - UINT32 - Zero (Allways) 2b - UINT16 - Area ID 2b - UINT16 - Node ID 4b - UINT32 - Unknown - may be related into interpolation 2b - UINT16 - Allways 0x7FFE 2b - UINT16 - LinkID 6b - INT16[3] - Position (XYZ) 1b - BYTE - Path Width 1b - BYTE - Path Type 4b - UINT32 - Flags


 * Area ID
 * defines the area where the node lays in. Usually this is the same number as the one of the node file.


 * Node ID
 * defines the id of the node. This is important for linking the node to others. Using the node and area id nodes can be identified as unique. There cannot be 2 nodes with the same area and node id.


 * Link ID
 * points to an link in section 2. The link ID cannot point into another node file. It points to a link in the same node file. However this link is able to point to an node in another or the same area.


 * Position (X,Y,Z)
 * The world-coordinates of the node. To get the floating point X and Y coordinates divide the 16 bit integer by 8. For Z coords you have to divide by 128 (Unlike San Andreas).


 * Path Width
 * used to set the width of the paths. For cars this is related in how much space there is between 2 lanes. Divide the 8 bit unsigned integer by 8 to get the floating point value.


 * Path Type
 * descripes the type of an node. This is used to isolate certain nodes from others. For boats this is allways 0x01.


 * Flags
 * the flags are used to influence the behaviour of non-person-characters (NPC's), which are spawned along the paths on the nodes (See below).

Path Node Flags
0-4: unknown Flag 05: Emergency only Flag 06: Boats Flag 07: Unknown Flag 08: Exactly the same as 05 Flag 09: Intersection central node Flag 10: Is highway Flag 11: Is not highway 12-15: Link count Flag 16: Disable linking 17-23: unknown (Perhaps related to lanes or other earlier Navi node flags) Flag 24: Is ped node? Flag 25: Rarely used, police controls or roadblocks? Flag 26: unknown ped flag Flag 27: Unknown ped flag 28-31: unknown


 * Structure unconfirmed and partially incomplete

Section 2 - Links
2b - UINT16 - Area ID 2b - UINT16  - Node ID 1b - UINT8   - Unknown 1b - UINT8  - Link length 2b - UINT16 - Flags


 * Structure unconfirmed and partially incomplete

Tools and Scripts

 * – a tool by which allows to view paths and highlight nodes with special flags in 3D.