Unity URPShader：实现和PS一样的色相/饱和度调整参数效果（修复）
目录
前言：
一、问题原因
二、算法修复
三、全代码
前言：
在之前的文章我已经实现了标题所述的内容功能：Unity URPShader：实现和PS一样的色相/饱和度调整参数效果-CSDN博客
但在偶然测试的时候，发现当采样的图片为白色或者是调整的颜色为白色时，会导致最终的画面渲染为黑色，今天对其进行修复。
一、问题原因
产生这样的原因在于颜色传入时，色相算法与饱和度算法计算出的颜色都是黑色，所以导致问题出错。回到PS后，在调节色相或者是饱和度时，其中白色依然不会改变，唯有亮度参数会对其进行效果改变。
二、算法修复
只需要判断输入的颜色是否时白色即可，以下时算法调整的地方：
half isWhite = saturate(floor(color.r * color.g * color.b));if (isWhite < 0.5){//Huehalf3 hsv = RGB2HSV(color.rgb);hsv.x = frac(hsv.x + _Hue / 360.0);color.rgb = HSV2RGB(hsv);//Saturationcolor.rgb = Saturation(color.rgb, _Saturation);}三、全代码
Shader "Background_Custom_HSV"
{Properties{_PatternTex ("贴图", 2D) = "black" { }[Header(BaseColor)][Space][HDR]_Color0 ("颜色", Color) = (1, 1, 1, 1)[Header(HSL)][Space]_Hue ("Hue", Range(-180, 180)) = 0.0_Saturation ("Saturation", Range(-100, 100)) = 0.0_Lightness ("Lightness", Range(-100, 100)) = 0.0}SubShader{Tags { "RenderType" = "Transparent" "Queue" = "Transparent" "RenderPipeline" = "UniversalPipeline" "IgnoreProjector" = "True" }Pass{Blend SrcAlpha OneMinusSrcAlphaZWrite OffCull BackHLSLPROGRAM#pragma vertex vert#pragma fragment frag#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"TEXTURE2D(_PatternTex);SAMPLER(sampler_PatternTex);CBUFFER_START(UnityPerMaterial)half3 _Color0;float _Hue;float _Saturation;float _Lightness;CBUFFER_ENDstruct Attributes{float4 positionOS : POSITION;float2 texcoord : TEXCOORD0;};struct Varyings{float4 positionHS : SV_POSITION;float2 uv : TEXCOORD0;};// RGB转HSV/HSBhalf3 RGB2HSV(half3 c){half4 K = half4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);half4 P = lerp(half4(c.bg, K.wz), half4(c.gb, K.xy), step(c.b, c.g));half4 Q = lerp(half4(P.xyw, c.r), half4(c.r, P.yzx), step(P.x, c.r));half D = Q.x - min(Q.w, Q.y);half E = 1e-10;return half3(abs(Q.z + (Q.w - Q.y) / (6.0 * D + E)), D / (Q.x + E), Q.x);}// HSV/HSB转RGBhalf3 HSV2RGB(half3 c){half4 K = half4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);half3 P = abs(frac(c.xxx + K.xyz) * 6.0 - K.www);return c.z * lerp(K.xxx, saturate(P - K.xxx), c.y);}half3 Saturation(half3 color, float saturation){half rgbMax = max(color.r, max(color.g, color.b));half rgbMin = min(color.r, min(color.g, color.b));half delta = rgbMax - rgbMin;// if (delta > 0)// {// half value = rgbMax + rgbMin;// half L = value * 0.5;// half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));// half percent = saturation * 0.01;// half alpha = 0;// half3 final_color = 0;// if (percent >= 0)// {// if (percent + S >= 1)// alpha = S;// else// alpha = 1 - percent;// alpha = 1 / alpha - 1;// final_color = color + (color - half3(L, L, L)) * alpha;// }// else// {// alpha = percent;// final_color = L + (color - half3(L, L, L)) * (1 + alpha);// }// return final_color;// }// else// return color;half value = rgbMax + rgbMin;half L = value * 0.5;half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));half percent = saturation * 0.01;half3 final_color = lerp(L + (color - L.xxx) * (1 + percent),color + (color - L.xxx) * (1.0 / (lerp(1.0 - percent, S, step(1.0, percent + S))) - 1.0),step(0.0, percent));final_color = lerp(color, final_color, ceil(delta));return final_color;}Varyings vert(Attributes v){Varyings o;o.positionHS = TransformObjectToHClip(v.positionOS.xyz);o.uv = v.texcoord;return o;}half4 frag(Varyings i) : SV_Target{half4 color = SAMPLE_TEXTURE2D(_PatternTex, sampler_PatternTex, i.uv);color.rgb *= i.colors.rgb;half isWhite = saturate(floor(color.r * color.g * color.b));if (isWhite < 0.5){//Huehalf3 hsv = RGB2HSV(color.rgb);hsv.x = frac(hsv.x + _Hue / 360.0);color.rgb = HSV2RGB(hsv);//Saturationcolor.rgb = Saturation(color.rgb, _Saturation);}//Valuehalf value = _Lightness * 0.01;// if (value > 0)// color.rgb = (1 - value) * color.rgb + half3(1.0, 1.0, 1.0) * value;// else if (value < 0)// color.rgb = color.rgb * (1.0 + value);color.rgb = lerp(color.rgb * (1.0 + value), lerp(color.rgb, half3(1.0, 1.0, 1.0), value), step(0.0, _Lightness));color.rgb = saturate(color.rgb);return color;}ENDHLSL}}FallBack "Hidden/Universal Render Pipeline/FallbackError"
}