// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
//扭曲外扩
Shader "YXJ/Effect/DistortionExternal" {
	Properties{
		_Alpha("Alpha", range(0,1)) = 1
		_MaskTex("Mask Tex (A)", 2D) = "white" {}
		_NoiseTex("Noise Texture (RG)", 2D) = "white" {}
		_HeatTime("Heat Time", range(0,1.5)) = 1
		_HeatForce("Heat Force", range(0,5)) = 0.1
		_CutAlpha("小于此alpha 跟着顶点a做渐变", range(0,1)) = 0.3
	}

	Category{
		Tags{ "Queue" = "Transparent+100" "IgnoreProjector" = "True"  "RenderType" = "Transparent" "LightMode" = "Grab_YXJ" }
		Cull Off Lighting Off ZWrite Off

		SubShader{
			LOD 300
			Blend SrcAlpha OneMinusSrcAlpha
			AlphaTest Greater .01

			Pass{
				HLSLPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma fragmentoption ARB_precision_hint_fastest
				#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
				#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"

				struct appdata_t {
					float4 vertex : POSITION;
					half4 color : COLOR;
					float2 texcoord: TEXCOORD0;
				};

				struct v2f {
					float4 vertex : SV_POSITION;
					half4 color : COLOR;
					float2 uvMask : TEXCOORD0;
					float4 uvGrab : TEXCOORD1;					
				};

				sampler2D _MaskTex; 
				float4 _MaskTex_ST;
				sampler2D _NoiseTex; 
				float4 _NoiseTex_ST;
				
				half _HeatTime;
				half _HeatForce;
				half _Alpha;
				half _CutAlpha;

				SAMPLER(_CameraTransparentTexture);

				v2f vert(appdata_t v)
				{
					v2f o;
					o.vertex = TransformObjectToHClip(v.vertex);
					o.color = v.color;
					o.uvMask = TRANSFORM_TEX(v.texcoord, _MaskTex);
					#if UNITY_UV_STARTS_AT_TOP
						float scale = -1.0;
					#else
						float scale = 1.0;
					#endif

					o.uvGrab.xy = (float2(o.vertex.x, o.vertex.y * scale) + o.vertex.w) * 0.5;
					o.uvGrab.zw = o.vertex.zw;

					return o;
				}
				
				half4 frag(v2f i) : COLOR
				{
					//noise effect, 外扩
					half4 offsetColor1 = tex2D(_NoiseTex, i.uvMask - _Time.xz * _HeatTime);

					i.uvGrab.x += ((offsetColor1.r + offsetColor1.r) - 1) * _HeatForce;
					i.uvGrab.y += ((offsetColor1.g + offsetColor1.g) - 1) * _HeatForce;

					half4 grab = tex2D(_CameraTransparentTexture, i.uvGrab.xy / i.uvGrab.w);
					half4 mask = tex2D(_MaskTex, i.uvMask);
					half maskA = min(mask.r, mask.a) * _Alpha;
					if(i.color.a < _CutAlpha) maskA = maskA * i.color.a;
					return half4(grab.rgb, maskA);
				}
				ENDHLSL
			}
		}

		
	}
}