95-Shader__GrabTexture Shader-NewUnlitShader.shader.txt

Shader "Unlit/#NAME#"
{
// The grab pass lets you access a texture of what has been rendered before.
// https://docs.unity3d.com/Manual/SL-GrabPass.html
// If you're just changing colour, you probably just want to use blend modes,
//  but using the grab pass lets you change what pixel you're sampling for distortion effects.
// This shader should appear invisible because I'm not changing anything yet.

	Properties
	{
		
	}
	SubShader
	{
		Tags {
			"RenderType"="Opaque"
			"Queue" = "Transparent"
			}
		LOD 100
		// _BackgroundTexture is an arbitrary name
		// If multiple meshes or shaders use the same name, it will use the same texture for all of them
		// If another shader uses a different name, it's supposed to grab another grab pass at that time
		GrabPass{
			"_BackgroundTexture"
		}
		Pass
		{
			
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
			};

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

			sampler2D _BackgroundTexture;
			float4 _BackgroundTexture_TexelSize;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				//this is a dumb thing where some computers have inverted y co-ordinates from others
				//but at least Unity provides a constant that lets you know if that's the case
#if UNITY_UV_STARTS_AT_TOP
				float scale = -1;
#else
				float scale = 1;
#endif
				o.uv.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;
				//----------------------
				o.uv.zw = o.vertex.zw;
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				// sample the grab texture
				fixed4 col = tex2Dproj( _BackgroundTexture, UNITY_PROJ_COORD(i.uv));
				return col;
			}
			ENDCG
		}
	}
}