Skyrim Mod:Mod File Format/NVNM Field

NVNM fields contain navmesh geometry data.

Name	Type/Size	Info
Unknown	uint32	Seems to always be 12 or 0x0000000C. I suspect it's a copy of NVER.
Location Marker?	uint32	Appears before location info.
World Space	formid	Formid of the world space. If World Space = 0x0000003C then the following uint32 contains grid info, otherwise it contains a cell formid. Is null(0x0000000) for interior cells.
Cell/Grid	formid or sint16 & sint16	These four bytes are the UInt32 Formid of the cell if the World Space above is null(0x0000), Otherwise this is a pair of two signed shorts representing grid coordinates of the exterior cell. Note that grid coordinates are in reverse order (first one is Y and second one is X).
Vertices	struct Vertex[num]	List of vertices in the navmesh. It contains the length of the list followed by repeating sequence of three floats that correspond to the 3d position of each vertex.
Num_Vertices (nvert)	int32	This is a number of vertices in the navmesh.
X:	float32	This is a repeating structure (occurs num_Vertices times) of X,Y and Z coordinates that make up the vertices in the navmesh. The values are the game coordinates of the vertices (same coordinate system as placed objects. A vertex at 0,0,0 will overlap with an object placed at 0,0,0 in the Creation Kit)
Y:	float32
Z:	float32
Triangles	struct Triangle[num]	List of Triangles in the navmesh. rowspan=8|struct Triangle: This is a repeating structure (occurs Num_Tris times) of 3 vertex indices, 3 edge neighbour indices, a cover marker and cover flags. The edges are either -1 if they don't border another triangle, or they hold the index of the triangle they do border. The cover marker seems to be an indicator of where the cover flags begin and usually contains 0x0008 or 0x0408. Flags Info 0000 No cover 0001 Open edge with no cover 0010 Wall with no cover 0011 Ledge cover 0100 64(units) 0101 80(units) 0110 96(units) 0111 112(units) 1000 128(units) 1001 144(units) 1010 160(units) 1011 176(units) 1100 192(units) 1101 208(units) 1110 224(units) 1111 Max cover(255 units) The cover flags are contained in a uint16 size of data. Only 2 edges of a triangle are allowed to have cover. size of uint16 Unknown edge 1 Unknown edge 0 1111 00 1111 00 1111
Num_Tris	int32	This is the number of triangles in the list.
Vertex 0	int16	Index of first vertex from the above Vertices list.
Vertex 1	int16	Index of second vertex from the above Vertices list.
Vertex 2	int16	Index of third vertex from the above Vertices list.
Edge 0	int16	Index within this list of the triangle that neighbors the first edge (vertex 0 to vertex 1)
Edge 1	uint16	Index within this list of the triangle that neighbors the second edge (vertex 1 to vertex 2)
Edge 2	uint16	Index within this list of the triangle that neighbors the third edge (vertex 2 to vertex 1)
Cover marker?	uint16
Cover flags	uint16
External Connections	struct Connection[num]	This is a list of triangles that border other navmeshes
Unknown	uint32	struct Connection: This struct is made up of an unknown int32, Navmesh formid and triangle index. The triangle index identifies the triangle that connects to the external navmesh, indicated by the navmesh formid.
Navmesh	formid
Triangle	int16
Door triangles	struct Door triangle[num]	This is a list of triangles at the door threshold.
Number	int32	Number of Triangles in the list
Triangle	int16	Index of a triangle from triangles list above.
Unknown	uint32	Appears to be a marker for door REFR formids.
Door REFR	formid	Form-ID of the linked DOOR reference.
Cover triangles	int16[num]	This is a list of triangles that have cover.
Cover triangle	int16	Index of triangle that has cover.
Divisor?	uint32	This appears to be a divisor to determine distance. The formula is ABS(( MaxX - MinX ) / Divisor ) = Max X Distance. (It may not necessarily be the maximum distance, but the formula fits the result).
Max X Distance	float32	This is result for X from the formula above.
Max Y Distance	float32	This is result for Y from the formula above.
Min X	float32	Min X of the navmesh.
Min Y	float32	Min Y of the navmesh.
Min Z	float32	Min Z of the navmesh.
Max X	float32	Max X of the navmesh.
Max Y	float32	Max Y of the navmesh.
Max Z	float32	Max Z of the navmesh.
Triangles	structure as follows:	This is a repeating sequence of lists that occurs divisor^2 times. It appears to divide the navmesh into 2d segments.
Length	uint32	The number of indexes in this segment.
Triangle index	uint16	Index of triangle from the triangle list that belong to this segment.