Water (WATR)¶

Fallout 4 water is defined by WATR records that control visual appearance (fog, reflections, specular, noise, silt) and gameplay effects (damage spells, sounds). Each exterior cell or worldspace references a water type and a water height, and the engine renders a flat plane at that elevation using the WATR's material properties.

Data Flow¶

WRLD record
  -> default water type (DNAM -> WATR FormID)
  -> default water height (NAM2 -> float32)

CELL record
  -> XCLW (water height, float32) — overrides worldspace default
  -> XCWT (water type, FormID)   — overrides worldspace default

Interior cells can also have water if the Has Water flag (bit 1 of CELL DATA) is set.

WATR Record¶

Type code: WATR

Top-Level Subrecords¶

Subrecord	Type	Description
EDID	zstring	Editor ID
FULL	lstring	Display name
ANAM	uint8	Opacity (0-255)
FNAM	uint8	Flags (see below)
TNAM	formid	Material type (MATT)
SNAM	formid	Open sound (SoundDescriptor)
XNAM	formid	Consume spell (on drinking)
YNAM	formid	Contact spell (on touching)
INAM	formid	Image space modifier
DATA	bytes	Unknown
DNAM	struct	Main visual data (201 bytes, see below)
GNAM	bytes	Unknown
NAM0	3x float32	Linear velocity (X, Y, Z)
NAM1	3x float32	Angular velocity (X, Y, Z)
NAM2	zstring	Noise layer 1 texture path
NAM3	zstring	Noise layer 2 texture path
NAM4	zstring	Noise layer 3 texture path

Flags (FNAM)¶

Bit	Name
0x01	Dangerous
0x04	Directional Sound

DNAM — Visual Data (201 bytes)¶

Fog Properties¶

Offset	Type	Field
0x00	float32	Fog Depth Amount
0x04	RGBA	Fog Shallow Color
0x08	RGBA	Fog Deep Color
0x0C	float32	Fog Color Shallow Range
0x10	float32	Fog Color Deep Range
0x14	float32	Fog Shallow Alpha
0x18	float32	Fog Deep Alpha
0x1C	float32	Fog Alpha Shallow Range
0x20	float32	Fog Alpha Deep Range
0x24	RGBA	Fog Underwater Color
0x28	float32	Fog Underwater Amount
0x2C	float32	Fog Underwater Near
0x30	float32	Fog Underwater Far

Physical Properties¶

Offset	Type	Field
0x34	float32	Normal Magnitude
0x38	float32	Shallow Normal Falloff
0x3C	float32	Deep Normal Falloff
0x40	float32	Reflectivity Amount
0x44	float32	Fresnel Amount
0x48	float32	Surface Effect Falloff
0x4C	float32	Displacement Simulator Force
0x50	float32	Displacement Simulator Velocity
0x54	float32	Displacement Simulator Falloff
0x58	float32	Displacement Simulator Dampener
0x5C	float32	Displacement Simulator Starting Size
0x60	RGBA	Reflection Color

Specular Properties¶

Offset	Type	Field
0x64	float32	Sun Specular Power
0x68	float32	Sun Specular Magnitude
0x6C	float32	Sun Sparkle Power
0x70	float32	Sun Sparkle Magnitude
0x74	float32	Interior Specular Radius
0x78	float32	Interior Specular Brightness
0x7C	float32	Interior Specular Power

Noise Layers (3 layers, interleaved)¶

Fields are grouped by property, with all 3 layers stored consecutively.

Offset	Type	Field
0x80	float32 x3	Wind Direction (layers 1, 2, 3)
0x8C	float32 x3	Wind Speed (layers 1, 2, 3)
0x98	float32 x3	Amplitude Scale (layers 1, 2, 3)
0xA4	float32 x3	UV Scale (layers 1, 2, 3)
0xB0	float32 x3	Noise Falloff (layers 1, 2, 3)

Each layer also has a texture path in NAM2/NAM3/NAM4 (see top-level subrecords).

Silt & Screen-Space¶

Offset	Type	Field
0xBC	float32	Silt Amount
0xC0	RGBA	Silt Light Color
0xC4	RGBA	Silt Dark Color
0xC8	uint8 (bool)	Screen Space Reflections

Total DNAM size: 201 bytes (0xC9).

Velocity¶

NAM0 and NAM1 define water flow as linear and angular velocity vectors. These control the direction and speed of surface animation and physics interaction. Both are world-space float32 triplets (X, Y, Z).

Cell & Worldspace References¶

Water type and height are resolved per-cell with a fallback chain:

CELL override: XCWT (water type) and XCLW (water height) on the cell record
Worldspace default: DNAM (default water type) and NAM2 (default water height) on the WRLD record
Interior cells: water only renders if Has Water flag is set in CELL DATA