How to convert vertex coordinates correctly in shader?

[yhl533556]

i just want do step-by-step with this tutorial: https://roystan.net/articles/grass-shader.html

but ,the position is not right. i donot know why?
shader Test17XuKongShengCao01 :ShaderBase,ComputeColor , Texturing ,Transformation
{
stream bool colorGreen;
stream float4 vertex : POSITION;
stream float3 normal : NORMAL;
stream float4 tangent :TANGENT;

float4 vertexOutput(float4 pos0, float3 posX)
{
float4 pos=mul(float4(posX,1),WorldViewProjection);
return pos+pos0;
}

[maxvertexcount(21)]
void GSMain(triangle  Input input[3] , inout TriangleStream<Output> triStream)
{
            float3 vNormal =input[0].normal;
            float4 vTangent =input[0].tangent;
            float3 vBinormal=cross(vNormal,vTangent)*vTangent.w;

            float3x3 tangentToLcal= float3x3(
            	vTangent.x, vBinormal.x, vNormal.x,
            	vTangent.y, vBinormal.y, vNormal.y,
            	vTangent.z, vBinormal.z, vNormal.z
            	);

            streams=input[0];                
            float4 posss0=streams.ShadingPosition;              
            streams.colorGreen=false;
            triStream.Append(streams);

            streams=input[1];
            streams.colorGreen=false;
            triStream.Append(streams);

            streams=input[2];
            streams.colorGreen=false;
            triStream.Append(streams);


            float4 f1=float4(-0.1, 0, 0 ,1);
            float4 f2=float4( 0.1, 0,0 ,1);
            float4 f3=float4(0, 0,1 ,1);


            float3 posss1=mul(tangentToLcal,f1.xyz);
            float3 posss2=mul(tangentToLcal,f2.xyz);
            float3 posss3=mul(tangentToLcal,f3.xyz);

            streams.ShadingPosition=vertexOutput(posss0,posss1);
            streams.colorGreen=true;
            triStream.Append(streams);
  
            streams.ShadingPosition=vertexOutput(posss0,posss2);
            streams.colorGreen=true;
            triStream.Append(streams);
                   
            streams.ShadingPosition=vertexOutput(posss0,posss3);
            streams.colorGreen=true;
            triStream.Append(streams);
}

    override stage void PSMain()
{
        if(streams.colorGreen)
        {
            streams.ColorTarget=float4(1,50,1,1);
        }
        else
        {
            streams.ColorTarget = float4(1,1,1,1);
        }
}

};

    public override void Update()
    {
        this.Entity.Get<ModelComponent>().Materials[0].Passes[0].Parameters.Set<Matrix>(WorldViewProjection, this.Entity.Get<TransformComponent>().WorldMatrix * Camera.ViewProjectionMatrix);
    }

[tebjan]

The ShadingPosition is usually already in screen space if you have a regular vertex shader.

float4 posss0=streams.ShadingPosition;

so maybe try:

float4 posss0=streams.Position;

because you multiply by WorldViewPostion in the vertexOutput method.