Question by torano · Feb 26, 2019 at 11:04 AM · shader rendertexture ripple

How to make dynamic ripple with shader?

Hi. I want to make a dynamic ripple shader such that a player touch a plane (raycast from camera) and a ripple effect is produced there. I made a simple shader as below and with changing _Center by using Raycast and passing uv(or world pos) value in script, I can produce a ripple at the point I want it to be, but the problem is that I can't make several ripples. If a player touches the plane 3 times, then 3 ripples should be produced and overlay each other. How can I make that kind of shader?

I tried CustomRenderTexture and its update zone but not work well neither... any help appreciated.

 Shader "Custom/Ripple"
 {
     Properties
     {
         _CircleColor("Circle Color", Color) = (0,0,0,1)
         _Center("Center", Vector) = (0, 0, 0, 0)
         _CircleWidth("Circle Width", float) = 0.98
         _Amplitude("Amplitude", float) = 4
         _Speed("Speed", float) = 20
         _BaseColor ("Base Color", Color) = (1,1,1,1)
     }
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 200
 
         CGPROGRAM
         // Physically based Standard lighting model, and enable shadows on all light types
         #pragma surface surf Standard fullforwardshadows
 
         // Use shader model 3.0 target, to get nicer looking lighting
         #pragma target 3.0
 
         sampler2D _MainTex;
 
         struct Input
         {
             float3 worldPos;
         };
 
         fixed4 _CircleColor;
         float4 _Center;
         fixed4 _BaseColor;
         float _CircleWidth;
         float _Amplitude;
         float _Speed;
 
 
         void surf (Input IN, inout SurfaceOutputStandard o)
         {
             float dist = distance(IN.worldPos, _Center);
             float val = abs(sin(dist * _Amplitude - _Time * _Speed));
             _CircleWidth = saturate(_CircleWidth) ;
             
             fixed4 color;
             if (val >= _CircleWidth) {
                 color = _CircleColor;
             } else {
                 color = _BaseColor;
             }
 
             o.Albedo = color;
         }
         ENDCG
     }
     FallBack "Diffuse"
 }

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