Shader "Custom/WaterWave Effect"
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{
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Properties
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{
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_MainTex ("Base (RGB)", 2D) = "white" {}
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}
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CGINCLUDE
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#include "UnityCG.cginc"
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uniform sampler2D _MainTex;
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uniform float _distanceFactor;
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uniform float _timeFactor;
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uniform float _totalFactor;
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uniform float _waveWidth;
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uniform float _curWaveDis;
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fixed4 frag(v2f_img i) : SV_Target
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{
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//计算uv到中间点的向量(向外扩，反过来就是向里缩)
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float2 dv = float2(0.5, 0.5) - i.uv;
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//按照屏幕长宽比进行缩放
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dv = dv * float2(_ScreenParams.x / _ScreenParams.y, 1);
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//计算像素点距中点的距离
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float dis = sqrt(dv.x * dv.x + dv.y * dv.y);
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//用sin函数计算出波形的偏移值factor
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//dis在这里都是小于1的，所以我们需要乘以一个比较大的数，比如60，这样就有多个波峰波谷
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//sin函数是（-1，1）的值域，我们希望偏移值很小，所以这里我们缩小100倍，据说乘法比较快,so...
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float sinFactor = sin(dis * _distanceFactor + _Time.y * _timeFactor) * _totalFactor * 0.01;
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//距离当前波纹运动点的距离，如果小于waveWidth才予以保留，否则已经出了波纹范围，factor通过clamp设置为0
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float discardFactor = clamp(_waveWidth - abs(_curWaveDis - dis), 0, 1);
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//归一化
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float2 dv1 = normalize(dv);
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//计算每个像素uv的偏移值
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float2 offset = dv1 * sinFactor * discardFactor;
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//像素采样时偏移offset
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float2 uv = offset + i.uv;
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return tex2D(_MainTex, uv);
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}
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ENDCG
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SubShader
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{
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Pass
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{
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ZTest Always
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Cull Off
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ZWrite Off
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Fog { Mode off }
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CGPROGRAM
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#pragma vertex vert_img
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#pragma fragment frag
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#pragma fragmentoption ARB_precision_hint_fastest
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ENDCG
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}
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}
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Fallback off
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}
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