UnlitGrid.shader

Shader "Unlit/Grid"
{
	Properties
	{
		_GridColour("Grid Colour", color) = (1, 1, 1, 1)
		_BaseColour("Base Colour", color) = (1, 1, 1, 0)
		_GridSpacing("Grid Spacing", float) = 0.1
		_LineThickness("Line Thickness", float) = 1
	}
		SubShader
	{
		Tags { "RenderType" = "Transparent" "Queue" = "Transparent"}
		LOD 100

		Blend SrcAlpha OneMinusSrcAlpha
		ZWrite Off

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			fixed4 _GridColour;
			fixed4 _BaseColour;
			float _GridSpacing;
			float _LineThickness;

			v2f vert(appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = mul(unity_ObjectToWorld, v.vertex).xz / _GridSpacing;

				return o;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				float2 wrapped = frac(i.uv) - 0.5f;
				float2 range = abs(wrapped);

				float2 speeds;
				/* // Euclidean norm gives slightly more even thickness on diagonals
				float4 deltas = float4(ddx(i.uv), ddy(i.uv));
				speeds = sqrt(float2(
							dot(deltas.xz, deltas.xz),
							dot(deltas.yw, deltas.yw)
						 ));
				*/  // Cheaper Manhattan norm in fwidth slightly exaggerates thickness of diagonals
				speeds = fwidth(i.uv);

				float2 pixelRange = range / speeds;
				float lineWeight = saturate(min(pixelRange.x, pixelRange.y) - _LineThickness);

				return lerp(_GridColour, _BaseColour, lineWeight);
			}
			ENDCG
		}
	}
}