//UNITY_SHADER_NO_UPGRADE
#ifndef WIND_ANIM
#define WIND_ANIM

// SmoothTriangleWave function
inline float SmoothTriangleWave(float x)
{
    // 将输入值限制在 [0, 1] 范围内，使用 frac 函数保证值是周期性的
    x = frac(x);

    // 使用三角函数生成平滑的波形，注意：frac(x) 生成的是 [0, 1] 之间的值
    return 1.0 - abs(2.0 * x - 1.0);  // 生成平滑的三角波
}

// SmoothTriangleWave function for a 4-component vector
inline float4 SmoothTriangleWave(float4 x)
{
    return float4(SmoothTriangleWave(x.x), SmoothTriangleWave(x.y), SmoothTriangleWave(x.z), SmoothTriangleWave(x.w));
}

inline void WindVert_float(float4 pos, float3 normal, float3 vertColor, float4 wind, float speed, float amplitude, out float4 aniPos)
{	
    // animParams.x = branch phase
    // animParams.y = edge flutter factor
    // animParams.z = primary factor
    // animParams.w = secondary factor


    float bendingFact = 1 - vertColor.b;
    //wind.xyz = TransformWorldToObject(wind.xyz);
    //wind.z = wind.z * bendingFact;

    float4 animParams = float4(0, amplitude, bendingFact.xx);
    float time = _Time.y * float2(speed, 1);


    float fDetailAmp = 0.1f;
    float fBranchAmp = 0.3f;

    // Phases (object, vertex, branch)
    float fObjPhase = dot(unity_ObjectToWorld[3].xyz, 1);
    float fBranchPhase = fObjPhase + animParams.x;

    float fVtxPhase = dot(pos.xyz, animParams.y + fBranchPhase);

    // x is used for edges; y is used for branches
    float2 vWavesIn = time  + float2(fVtxPhase, fBranchPhase );

    // 1.975, 0.793, 0.375, 0.193 are good frequencies
    float4 vWaves = (frac( vWavesIn.xxyy * float4(1.975, 0.793, 0.375, 0.193) ) * 2.0 - 1.0);

    vWaves = SmoothTriangleWave( vWaves );
    float2 vWavesSum = vWaves.xz + vWaves.yw;

    // Edge (xz) and branch bending (y)
    float3 bend = animParams.y * fDetailAmp * normal.xyz;
    bend.y = animParams.w * fBranchAmp;
    pos.xyz += ((vWavesSum.xyx * bend)*wind.w + (wind.xyz * vWavesSum.y * animParams.w)) * wind.w; 

    // Primary bending
    // Displace position
    pos.xyz += animParams.z * wind.xyz;

    aniPos = pos;
	
}


#endif