一个剪切shader 液体水

水柱效果 半成品

Shader "Unlit/剪切"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_h("h",float)=0.5
		_Color ("Section Color", Color) = (1,1,1,0)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100
		cull off
		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			#pragma multi_compile_fog
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
				float3 normal:NORMAL;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				UNITY_FOG_COORDS(1)
				float4 vertex : SV_POSITION;
				float3 worldPos:TEXCOORD2;
				// float3 worldPos:TEXCOORD1;
             float3 viewDir:TEXCOORD3;
             float3 worldNormal:TEXCOORD4;
			};
			float _h;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			float4  _Color;
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				UNITY_TRANSFER_FOG(o,o.vertex);
				o.worldPos=mul((float3x3)_Object2World,v.vertex);
				o.viewDir=WorldSpaceViewDir(v.vertex);
                o.worldNormal=UnityObjectToWorldNormal(v.normal);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				// sample the texture
				fixed4 col;
				if(i.worldPos.y>_h)
				{
				 clip(_h);
				 //return _Color;
				}

				float fd = dot( i.viewDir, i.worldNormal);

				if (fd.x > 0)
                {
                  col = tex2D (_MainTex, i.uv);
                  return col;
                }
				UNITY_APPLY_FOG(i.fogCoord, col);
				return col=_Color;
			}
			ENDCG
		}
	}
}