// Upgrade NOTE: upgraded instancing buffer 'Props' to new syntax.

Shader "Custom/JellyShader" {
	Properties {
		_Color ("Color", Color) = (1,1,1,1)
		_MainTex ("Albedo (RGB)", 2D) = "white" {}
		_Glossiness ("Smoothness", Range(0,1)) = 0.5
		_Metallic ("Metallic", Range(0,1)) = 0.0

		_ControlTime ("Time", float) = 0
		_ModelOrigin ("Model Origin", Vector) = (0,0,0,0)
		_ImpactOrigin ("Impact Origin", Vector) = (-5,0,0,0)

		_Frequency ("Frequency", Range(0, 1000)) = 10
		_Amplitude ("Amplitude", Range(0, 5)) = 0.1
		_WaveFalloff ("Wave Falloff", Range(1, 8)) = 4
		_MaxWaveDistortion ("Max Wave Distortion", Range(0.1, 2.0)) = 1
		_ImpactSpeed ("Impact Speed", Range(0, 10)) = 0.5
		_WaveSpeed ("Wave Speed", Range(-10, 10)) = -5
	}
	SubShader {
		Tags { 
			"RenderType"="Opaque" 
			"RenderPipeline"="UniversalPipeline"
			"UniversalMaterialType" = "SimpleLit"
			"LightMode"="UniversalForward"
		}
		LOD 200
		
		// Render State Commands
        // Use same blending / depth states as Standard shader
        Blend[_SrcBlend][_DstBlend], [_SrcBlendAlpha][_DstBlendAlpha]
        ZWrite[_ZWrite]
        Cull[_Cull]
        AlphaToMask[_AlphaToMask]

		HLSLPROGRAM
		// Use shader model 3.0 target, to get nicer looking lighting
		#pragma target 3.0
		#pragma vertex vert
		#pragma fragment frag
		#pragma surface surf Standard fullforwardshadows
        // -------------------------------------
        // Includes
        #include "Packages/com.unity.render-pipelines.universal/Shaders/SimpleLitInput.hlsl"
        #include "Packages/com.unity.render-pipelines.universal/Shaders/SimpleLitForwardPass.hlsl"

		sampler2D _MainTex;

		struct Input {
			float2 uv_MainTex;
		};

		half _Glossiness;
		half _Metallic;
		half4 _Color;

		float _ControlTime;
		float4 _ModelOrigin;
		float4 _ImpactOrigin;

		half _Frequency; //Base frequency for our waves.
		half _Amplitude; //Base amplitude for our waves.
		half _WaveFalloff; //How quickly our distortion should fall off given distance.
		half _MaxWaveDistortion; //Smaller number here will lead to larger distortion as the vertex approaches origin.
		half _ImpactSpeed; //How quickly our wave origin moves across the sphere.
		half _WaveSpeed; //Oscillation speed of an individual wave.

		// Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
		// See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
		// #pragma instancing_options assumeuniformscaling
		UNITY_INSTANCING_BUFFER_START(Props)
			// put more per-instance properties here
		UNITY_INSTANCING_BUFFER_END(Props)

		void vert (inout appdata_base v) {
			float4 world_space_vertex = mul(unity_ObjectToWorld, v.vertex);

			float4 direction = normalize(_ModelOrigin - _ImpactOrigin);
			float4 origin = _ImpactOrigin + _ControlTime * _ImpactSpeed * direction;
			
			//Get the distance in world space from our vertex to the wave origin.
			float dist = distance(world_space_vertex, origin);

			//Adjust our distance to be non-linear.
			dist = pow(dist, _WaveFalloff);

			//Set the max amount a wave can be distorted based on distance.
			dist = max(dist, _MaxWaveDistortion);

			//Convert direction and _ImpactOrigin to model space for later trig magic.
			float4 l_ImpactOrigin = mul(unity_WorldToObject, _ImpactOrigin);
			float4 l_direction = mul(unity_WorldToObject, direction);

			//Magic
			float impactAxis = l_ImpactOrigin + dot((v.vertex - l_ImpactOrigin), l_direction);

			v.vertex.xyz += v.normal * sin(impactAxis * _Frequency + _ControlTime * _WaveSpeed) * _Amplitude * (1 / dist);
		}

		void surf (Input IN, inout SurfaceOutputStandard o) {
			// Albedo comes from a texture tinted by color
			float4 c = _Color;
			//half4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			o.Albedo = c.rgb;
			// Metallic and smoothness come from slider variables
			o.Metallic = _Metallic;
			o.Smoothness = _Glossiness;
			o.Alpha = c.a;
		}
		ENDHLSL
	}
	FallBack "Diffuse"
}