创建一个瀑布效果着色器，包含瀑布流动、湍流、泡沫和冲击效果，支持下落速度和湍流强度调节。

float waterfallFlow(vec2 uv, float time) {
    float flow = 0.0;
    
    // 创建多层瀑布效果
    for (int i = 0; i < 3; i++) {
        float layer = float(i) * 0.2;
        float speed = fallSpeed * (1.0 + layer * 0.5);
        
        // 垂直流动效果
        float verticalFlow = sin(uv.y * 20.0 - time * speed + layer * 3.14);
        
        // 水平波动
        float horizontalWave = sin(uv.x * 10.0 + time * speed * 0.5) * 0.3 + 0.7;
        
        flow += verticalFlow * horizontalWave * (1.0 - layer * 0.3);
    }
    
    return flow * 0.5 + 0.5;
}

float turbulenceEffect(vec2 uv, float time) {
    float turb = 0.0;
    
    for (int i = 0; i < 2; i++) {
        float frequency = float(i + 1) * 5.0;
        turb += sin(uv.x * frequency + time * 2.0) * 
               sin(uv.y * frequency + time * 2.0) * 0.1;
    }
    
    return turb * turbulence;
}

float foamEffect(vec2 uv, float time) {
    float foam = 0.0;
    
    // 创建泡沫图案
    for (int i = 0; i < 4; i++) {
        float offset = float(i) * 0.5;
        foam += sin(uv.x * 15.0 + time * 3.0 + offset) * 
               sin(uv.y * 15.0 - time * 2.0 + offset) * 0.05;
    }
    
    return max(0.0, foam) * foamIntensity;
}

uniforms: {
    time: { value: 0 },
    resolution: { value: new THREE.Vector2(_width, _height) },
    fallSpeed: { value: 2.0 },
    turbulence: { value: 0.5 },
    foamIntensity: { value: 0.3 },
    waterColor: { value: new THREE.Color(0x4a90e2) }
}