Unity 黑白闪效果

ainatipen 发表于 2022-10-27 11:09

游戏中经常会使用将画面通过短暂的黑白闪来实现激烈的表现效果.如下图:

为了让特效有跟好的控制,目前使用较大粒子片盖在相机前实现整体思路如下:
1、截取画面Pass

URP中自带了屏幕颜色_CameraOpaqueTexture, 使用SampleSceneColor来获取,但是这个只是不透明层的.如果需要加入透明层物体,需要在不透明渲染之后插入一个CopyColorPass来实现. 这里_CameraTransparentTexture就是包含了透明物体的颜色缓冲.
public class TransparentTextureFeature:ScriptableRendererFeature
{

   private CustomCopyColorPass _copyColorPass;
   private Material m_SamplingMaterial;
   RenderTargetHandle m_TransparentColor;
   RenderTargetHandle m_CameraColorAttachment;
   public override void Create()
   {
         m_SamplingMaterial = CoreUtils.CreateEngineMaterial(Shader.Find(&#34;Hidden/Universal Render Pipeline/Sampling&#34;));
         _copyColorPass = new CustomCopyColorPass(RenderPassEvent.AfterRenderingTransparents, m_SamplingMaterial);
         m_TransparentColor.Init(&#34;_CameraTransparentTexture&#34;);
         m_CameraColorAttachment.Init(&#34;_CameraColorTexture&#34;);
   }

   public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
   {
         if ( renderingData.cameraData.renderType == CameraRenderType.Base)
         {
            _copyColorPass.Setup(m_CameraColorAttachment.Identifier(), m_TransparentColor, UniversalRenderPipeline.asset.opaqueDownsampling);
            renderer.EnqueuePass(_copyColorPass);
         }

   }

}2、黑白闪shader

这里计算原理就是, 先计算当前像素在屏幕中的位置,然后采样_CameraTransparentTexture纹理,得到屏幕像素. 然后计算灰度值, 通过step控制黑白阀值. 在用oneminus 得到黑白相反的颜色.
Shader &#34;Effect/Effect_GJ_URP_BlackWhite&#34;
{
Properties
{
   _BlackWhiteBlend (&#34;【BlackWhiteBlend】&#34;, range (0,1) ) = 0
   _BlackWhitePower (&#34;BlackWhitePower&#34;, range(0.1,30) ) = 1
   _BlackWhiteAphaStrength (&#34;BlackWhiteAphaStrength&#34;, range (0,5) ) = 5
}
SubShader
{
   Tags
   {
         &#34;IgnoreProjector&#34;=&#34;True&#34;
         &#34;Queue&#34;=&#34;Transparent&#34;
         &#34;RenderType&#34;=&#34;Transparent&#34;
   }
   Pass
   {
         Tags
         {
            &#34;LightMode&#34; = &#34;UniversalForward_BlackWhite&#34;
         }

         ZWrite On
         HLSLPROGRAM
         #pragma vertex vert
         #pragma fragment frag
         #include &#34;Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl&#34;
         CBUFFER_START (UnityPerMaterial)
         float _BlackWhiteBlend;
         float _BlackWhitePower;
         float _BlackWhiteAphaStrength;
         CBUFFER_END
         SAMPLER(_CameraTransparentTexture);

         struct VertexInput
         {
            float4 vertex : POSITION;
         };

         struct VertexOutput
         {
            float4 pos : SV_POSITION;
         };

         VertexOutput vert(VertexInput v)
         {
            VertexOutput o = (VertexOutput)0;
            o.pos = TransformObjectToHClip( v.vertex.xyz);
            return o;
         }

         float4 frag(VertexOutput i, float facing : VFACE) : COLOR
         {
            //BlackWhite
            //float4 blackwhite = float4(SampleSceneColor(i.pos.xy / _ScreenParams.xy), 1);
            float4 blackwhite = tex2D(_CameraTransparentTexture, i.pos.xy / _ScreenParams.xy);
            float grey = dot(blackwhite.rgb, float3(0.22, 0.707, 0.071));
            blackwhite.rgb = step(0.5, pow(grey, _BlackWhitePower));
            blackwhite.a = _BlackWhiteAphaStrength;
            return lerp(blackwhite, float4((1 - blackwhite).rgb, blackwhite.a), _BlackWhiteBlend);
         }
         ENDHLSL
   }
}
}3、效果调试

再UniversalPipelineAsset中设置TransparentTextureFeature抓取颜色缓冲, 然后再beforerenderpostprocess阶段渲染单独该粒子即可(正常渲染通过shadertag排除该粒子的渲染),配置如下

粒子系统控制_BlackWhiteBlend来实现效果,

mypro334 发表于 2022-10-27 11:09

直接用URP中的CopyColorPass一样效果,

DomDomm 发表于 2022-10-27 11:10

大佬可以分享一下工程吗

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Unity 黑白闪效果