🏄 Breaking Waves - Realistic Surf Zone Simulation in NextGen 2.0

For years, the #1 feature request from our community has been realistic breaking waves. With NextGen 2.0, we're delivering a complete Coastal Wave System that simulates the entire lifecycle of waves as they approach and break on your shores.

🌊 Understanding Wave Breaking

When ocean waves approach a coastline, they undergo a dramatic transformation:

1. Shoaling: Waves slow down and increase in height
2. Steepening: Wave faces become asymmetric
3. Breaking: The crest collapses forward
4. Surf: Chaotic white water rushes shoreward
5. Swash: Water runs up the beach
6. Backwash: Water retreats to sea

Our Breaking Wave system simulates all six phases in real-time.

🔬 SDF-Driven Simulation

The system is powered by Signed Distance Fields (SDF) that encode your shoreline geometry:

• Positive values: Distance from shore (deep water)
• Zero: The shoreline itself
• Negative values: Distance inland

The SDF gradient provides the perpendicular direction to shore, guiding waves toward beaches naturally.

// SDF gradient normalization with fallback
float2 SlopeDirRaw = SDFGradient;
float  SlopeLen = length(SlopeDirRaw);
float2 SlopeDirection = (SlopeLen > 1e-4f) 
    ? (SlopeDirRaw / SlopeLen) 
    : float2(1.0f, 0.0f);

📊 Wave Lifecycle Parameters

Control every aspect of the wave lifecycle:

struct FOceanologyShoreWaves
{
    bool CoastalWaves = true;        // Enable system
    
    // Wave geometry
    float BreakerStrength = 1000.0f; // Wave height
    float WaveLength = 4000.0f;      // Distance between waves
    float GlobalWaveScale = 0.5f;    // Overall scale
    
    // Wave motion
    float WavePhaseSpeed = 1.0f;     // Cycle speed
    float DirectionWaveSpeed = 512.0f; // Shore approach speed
    
    // Wave sway (lateral wobble)
    float SwayFrequency = 8192.0f;   // Sway wavelength
    float WaveSwayAmplitude = 300.0f; // Sway amount
    
    // Zone control
    float ShoreSlopeRange = 1000.0f; // Transition width
    float SurfZoneWidth = -1000.0f;  // Surf zone extent
    
    // Effects
    float ShorelineFoam = 1000.0f;   // Foam band width
    float FlowStrength = 1.0f;       // Water flow intensity
};

🎬 The Breaking Animation

Waves progress through timed lifecycle windows:

// Phase clock from 0 to CYCLETIME (4.5 seconds default)
float PhaseClock = fmod(TimeWrapped - DepthProjection/LocalWaveLength, CYCLETIME);
float TimeRatio = PhaseClock / CYCLETIME;

// Lifecycle windows
float WindowForm = 1.0 - smoothstep(0.00, 0.30, TimeRatio);      // Building
float WindowBreak = smoothstep(0.10, 0.40, TimeRatio) * 
                    (1.0 - smoothstep(0.40, 0.70, TimeRatio));   // Breaking
float WindowDissipate = smoothstep(0.50, 0.80, TimeRatio);       // Dissipating

Each window controls different aspects of geometry, foam, and motion.

🌀 Barrel Formation

The system creates realistic barrel/tube shapes during the breaking phase:

// Roll geometry
float2 RollBreak = float2(
    lerp(4.0, 16.0, LateralBreak),  // Roll tightness
    0.2 * (4.0 + BreakRamp)          // Vertical scale
);

// Crest curl calculation
float RollAngle = RollFactor * CrestRight * HALF_PI;
float CosRoll, SinRoll;
sincos(RollAngle, SinRoll, CosRoll);

The RollFactor increases through the breaking phase, creating the characteristic curling motion.

💨 Dynamic Foam Generation

Foam is generated based on wave physics:

// Foam factors
float WaveSlope = abs(CrestHeightDeriv) * EffectiveHeight;
float SlopeFactor = saturate((WaveSlope - 0.04) / 0.18);
float CrestFactor = saturate((CrestRight - 0.60) / 0.25);
float StageBoost = WindowBreak * (1.0 - WindowDissipate);

// Combined foam
float BaseFoam = saturate(0.6 * SlopeFactor + 0.4 * CrestFactor);
float BreakingFoam = BaseFoam * exp2(-DissipateRamp * 2.2) * DepthAtten;

Foam appears on steep wave faces and persists through the dissipation phase.

🏖️ Shoreline Foam Band

A separate foam band follows the water's edge:

float ShoreBand = 1.0 - saturate(abs(SDF) / ShorelineFoam);
float ShoreFoam = saturate(max(FoamPhase * 1.3 - 0.5, -0.1) + ShoreBand);

This creates the characteristic white foam line at the water's edge.

🌊 Wave Sway

Waves don't approach perfectly perpendicular - they sway laterally:

// World-space sway calculation
float2 SwayBasisWS = normalize(float2(1.0, 1.0));
float SwayOmega = TWO_PI / SwayFrequency;
float SwayCoord = dot(WorldPosition, SwayBasisWS);
float SwayShift = sin(SwayOmega * SwayCoord) * WaveSwayAmplitude;

This breaks up the artificial regularity of perfectly aligned waves.

🔀 Ocean Blending

Breaking waves smoothly blend with the deep ocean system:

// Surf zone factor
float SurfZoneRaw = saturate((SDF + SurfZoneWidth) / SURFZONE_SCALE);
float OceanBlend = pow(SurfZoneRaw, SURFZONE_GATE_POWER);

// Final outputs blend ocean and breaking
OutNormal = normalize(lerp(BreakingNormal, OceanNormal, OceanBlend));
OutFoam = lerp(ShoreFoam, OceanFoam, OceanBlend);

No harsh transitions - just smooth blending from deep water to surf zone.

🎨 Wave Forge Integration

For ultimate artistic control, use Wave Forge Studio to create custom wave profiles:

• 21 Hermite splines define the complete wave shape
• Procedural mode: Real-time spline evaluation
• Baked mode: Texture-based for maximum performance

// Baked profile sampling
float2 Projection2D = Texture2DSample(
    BakeProjection2D, 
    BakeProjection2DSampler, 
    UVs
).rg;

// Convert to world displacement
float3 worldOffset = float3(
    Gradient * projectedDisplacement.x, 
    projectedDisplacement.y
);

⚙️ Best Practices

For Realistic Surf

BreakerStrength: 800-1200
WaveLength: 3000-5000
SurfZoneWidth: -800 to -1200
ShorelineFoam: 800-1200

For Gentle Beaches

BreakerStrength: 400-600
WaveLength: 5000-8000
SwayAmplitude: 150-200
ShorelineFoam: 500-800

For Dramatic Coastlines

BreakerStrength: 1500-2000
WaveLength: 2000-3000
GlobalWaveScale: 0.7-1.0
FlowStrength: 1.5-2.0

📊 Performance

Breaking waves only compute in the surf zone:

if (!WaveParams.CoastalWaves)
{
    // Skip computation, pass through ocean data
    OutWaves.WPO = WaterDisplacement;
    OutWaves.Normal = WaterNormal;
    OutWaves.Foam = WaterFoam;
    return OutWaves;
}

Outside the surf zone, there's zero overhead.

Benchmark (RTX 4070, 1080p, 500m coastline):

• Breaking waves: ~0.4ms
• With foam: ~0.5ms
• Full system: ~0.6ms

🎮 Use Cases

• Tropical beaches: Gentle rollers with clear barrels
• Rocky coasts: Dramatic plunging breakers
• River mouths: Complex wave interference
• Harbors: Calm protected waters with distant breaking

🚀 Coming in 2.0

Breaking Waves will be available as a free update for all NextGen customers. Start planning your coastlines now!

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Questions about Breaking Waves? Join our Discord!