How am I implementing this grass shader incorrectly?

Hey folks,

I'm trying to follow this tutorial, but I'm running into problems.. can anybody suggest a solution?

I'm supposed to be getting a response like this...

...but instead, my model is showing up as this:

I assume this is to do with the relative positions of the origins on the respective models. Presuming this is to do with world origins... but trying to subtract -5 from the normalised values seems to do very little. My code is as follows...

 Shader "RS/LRGrass"
 {
     Properties
     {
         _Color        ("Color", Color)            = (1,1,1,1)
         _MainTex    ("Albedo (RGB)", 2D)        = "white" {}
         _Glossiness ("Smoothness", Range(0,1))    = 0.5
         _Metallic    ("Metallic", Range(0,1))    = 0.0
  
         _WindTex ("Wind Texture", 2D) = "white" {}
         _WorldSize    ("World Size", vector)        = (1,1,1,1)
         _WindSpeed ("Wind Speed", vector)        = (1,1,1,1)
     }
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 200
  
         Pass
         {
             CGPROGRAM
  
             #pragma vertex vert
             #pragma fragment frag
            
             struct vertexInput
             {
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
             };
  
             struct vertexOutput
             {
                 float4 pos : SV_POSITION;
                 float3 normal : NORMAL;
                 float2 sp : TEXCOORD0; //Test sample position
             };
  
             sampler2D    _WindTex;
             vector        _WorldSize;
             vector        _WindSpeed;
  
             vertexOutput vert(vertexInput input)
             {
                 vertexOutput output;
  
                 // convert input to clip and world space
                 output.pos        = UnityObjectToClipPos(input.vertex);
                 float4 normal4    = float4(input.normal, 0.0f);
                 output.normal    = normalize(mul(normal4, unity_WorldToObject).xyz);
  
                 // get vertex world position
                 float4 worldPos = mul(input.vertex, unity_ObjectToWorld);
                 // normalize position based on world Size
                 float2 samplePos = worldPos.xz / _WorldSize.xz;
  
                 // scroll sample position based on time
                 // samplePos += _Time.x * _WindSpeed.xy;
  
                 // Sample wind texture
                 //float windSample = tex2Dlod (_WindTex, float4(samplePos, 0, 0));
  
                 output.sp = samplePos; // Test sample position.
  
                
  
                 return output;
             };
            
             float4 frag (vertexOutput input) : COLOR
             {
                 return float4(input.sp.x, 0, 0, 1); // Temporary measure!
             };
  
             ENDCG
         }
  
         /*
         CGPROGRAM
         // Physically based Standard lighting model, and enable shadows on all light types
         #pragma surface surf Standard fullforwardshadows
        
         // Use shader model 3.0 target, to get nicer looking lighting
         #pragma target 3.0
  
         sampler2D _MainTex;
  
         struct Input
         {
             float2 uv_MainTex;
         };
  
         half _Glossiness;
         half _Metallic;
         fixed4 _Color;
  
         // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
         // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
         // #pragma instancing_options assumeuniformscaling
         UNITY_INSTANCING_BUFFER_START(Props)
             // put more per-instance properties here
         UNITY_INSTANCING_BUFFER_END(Props)
  
         void surf (Input IN, inout SurfaceOutputStandard o)
         {
             // Albedo comes from a texture tinted by color
             fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
             o.Albedo = c.rgb;
             // Metallic and smoothness come from slider variables
             o.Metallic = _Metallic;
             o.Smoothness = _Glossiness;
             o.Alpha = c.a;
         }
         ENDCG
         */
     }
     FallBack "Diffuse"
 }

 

Can anybody help me out with this? Really confused here and I'd like to have it sorted soon...!