How can I overwrite the built-in grass shader?

I am trying to overwrite the built-in terrain grass shader so that I can edit it. I have imported the built-in grass shader to work off of, but my terrain seems to not be using the imported shader. No matter what I do with the shader, my grass still looks the same. I have no errors or warnings, and I have not renamed or changed the built-in shader that I downloaded.

(I am using Unity 5.3.1)

Thank you for your time, I would greatly appreciate any input.

This is the shader I downloaded (I am aware that non-billboarded grass uses a different shader, and my grass is set to billboard):

Shader "Hidden/TerrainEngine/Details/BillboardWavingDoublePass" {
	Properties {
		_WavingTint ("Fade Color", Color) = (.7,.6,.5, 0)
		_MainTex ("Base (RGB) Alpha (A)", 2D) = "white" {}
		_WaveAndDistance ("Wave and distance", Vector) = (12, 3.6, 1, 1)
		_Cutoff ("Cutoff", float) = 0.5
	}
	
CGINCLUDE
#include "UnityCG.cginc"
#include "TerrainEngine.cginc"

struct v2f {
	float4 pos : SV_POSITION;
	fixed4 color : COLOR;
	float4 uv : TEXCOORD0;
};
v2f BillboardVert (appdata_full v) {
	v2f o;
	WavingGrassBillboardVert (v);
	o.color = v.color;
	
	o.color.rgb *= ShadeVertexLights (v.vertex, v.normal);
		
	o.pos = mul (UNITY_MATRIX_MVP, v.vertex);	
	o.uv = v.texcoord;
	return o;
}
ENDCG

	SubShader {
		Tags {
			"Queue" = "Geometry+200"
			"IgnoreProjector"="True"
			"RenderType"="GrassBillboard"
			"DisableBatching"="True"
		}
		Cull Off
		LOD 200
		ColorMask RGB
				
CGPROGRAM
#pragma surface surf Lambert vertex:WavingGrassBillboardVert addshadow exclude_path:deferred
			
sampler2D _MainTex;
fixed _Cutoff;

struct Input {
	float2 uv_MainTex;
	fixed4 color : COLOR;
};

void surf (Input IN, inout SurfaceOutput o) {
	fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * IN.color;
	o.Albedo = c.rgb;
	o.Alpha = c.a;
	clip (o.Alpha - _Cutoff);
	o.Alpha *= IN.color.a;
}

ENDCG			
	}

	Fallback Off
}

EDIT: From the comments below: “I found that it needed to refresh the grass somehow. I noticed this because I painted some more grass then hit ctrl-z and my grass refreshed with the new shader.”

OK, not sure what’s going on here but here’s what I did to test:

  1. Made a basic terrain
  2. Created a new ‘grass’ detail (billboard etc)
  3. Painted it on to test. Everything is fine.
  4. I then created a new shader file (I just called it “MyGrassShader”)
  5. Replaced the entire contents with what you provided above and everything was still fine
  6. I then just added ‘c.r =1.0’’ on line 55 to force the r channel to 1
  7. The detail changed to be more red.
  8. If I make a deliberate mistake then I get errors in the console as you would expect

So, as far as I can see this all works and the only thing I’ve done different is to basically rename the file as “MyGrassShader”.

To confirm, this was a completely new, empty project on unity 5.3.3f1

Not sure if that helps or not, but at least it’s something!