Choosing a wave spectrum

DRW ships three wave spectrum models. Each represents a different sea state. Picking the right one is the single most impactful decision you’ll make about ocean look.

The three spectra

Phillips

The classic textbook spectrum: simple, fast, tunable. Pick Phillips when:

• You’re prototyping and want a working ocean fast.
• You want the most direct control over wave amplitude per cascade.
• Your scene calls for stylised / non-realistic water.

Phillips is forgiving but doesn’t model “fully developed” or “growing” sea states with much physical fidelity. It’s the default in BP_DynamicRealWater for that reason.

Pierson-Moskowitz (PM)

A “fully developed sea” model: wind has been blowing long enough that wave energy has saturated. Looks smooth, regular, oceanic.

Pick PM when:

• The scene is set in open ocean far from shore.
• You want a “stable weather” look.
• Long swells and a settled feel are the goal.

JONSWAP

The “growing sea” / “fetch-limited” model. Sharper energy peaks than PM, with more pronounced dominant waves.

Pick JONSWAP when:

• You want stormy or coastal seas with definite character.
• Storm fronts, weather transitions, dramatic cinematic shots.
• The water is “doing something”: not at rest, not fully developed.

Authoring per-cascade values

DRW runs four wave cascades simultaneously (short, medium, long, very-long wavelengths). Most spectrum properties are FVector4: one value per cascade. This is why you can have, say, a heavy long-wave swell with calm short-wave detail (or vice-versa).

The shipped wave presets in Plugins/DynamicRealWater/Content/Blueprints/WaterStates/Waves/ (DA_P_SmallWaves, DA_P_MediumWaves, DA_P_HighWaves) are good study material: each is built from the same spectrum but with different amplitude / damping per cascade.

Switching at runtime

SetOceanWaveData(WaveData, BlendDuration) blends from the current spectrum into a new one over time. Use this for storm rolls-in, day / night calm transitions, or dynamic weather.

Tip

When in doubt, start with Phillips for prototyping, then switch to JONSWAP for the final look: it’s the most cinematic of the three for most scenes.