文章目录

许多游戏使用非真实感渲染（NPR）的方法渲染游戏画面，例如卡通和水彩风格等；

卡通渲染

渲染轮廓线

这里使用过程式几何轮廓线渲染：使用两个Pass，第一个Pass使用轮廓线颜色渲染整个背面的面片，并在视角空间下把模型顶点沿着法线方向向外扩张一段距离，让背部轮廓线清晰可见；为了防止对于一些内凹的模型，背面面片遮挡正面面片的情况，在扩张背面顶点之前，先对顶点法线的z分量处理，使它们等于一个定值，然后把法线归一化后再对顶点扩张，使扩展后的背面更加扁平化，降低了遮挡正面面片的可能性。

优点是快速有效，适用于绝大多数表面平滑的模型，但不适合立方体这样平整的模型；

viewNormal.z=-0.5;viewNormal=normalize(viewnormal);viewPos=viewPos+viewNormal*_Outline;

高光

以往的高光模型不再可用，这里计算normal和halfDir的点乘结果，和一个阈值比较，为了防止高光边界出现锯齿，可以使用以下代码：

float spec=dot(worldNormal,worldHalfDir);spec=lerp(0,1,smoothstep(-w,w,spec-threshold));

w是一个很小的值，当spec-threshold小于-w时，高光系数返回0，大于w时返回1，否则在0到1之间插值，这样可以使高光区域的边界处得到一个从0到1平滑变化的spec值；

这里使用领域像素之间的近似导数值，使用fwidth函数实现；

实现

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'Shader "Unity Shaders Book/Chapter 14/Toon Shading" {Properties {_Color ("Color Tint", Color) = (1, 1, 1, 1)_MainTex ("Main Tex", 2D) = "white" {}_Ramp ("Ramp Texture", 2D) = "white" {} //控制漫反射色调的渐变纹理_Outline ("Outline", Range(0, 1)) = 0.1 //控制轮廓线宽度_OutlineColor ("Outline Color", Color) = (0, 0, 0, 1) //轮廓线颜色_Specular ("Specular", Color) = (1, 1, 1, 1)//高光反射颜色_SpecularScale ("Specular Scale", Range(0, 0.1)) = 0.01//计算高光反射时使用的阈值}SubShader {Tags {"RenderType"="Opaque" "Queue"="Geometry"}Pass {NAME "OUTLINE"//只渲染背面Cull Front CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"float _Outline;fixed4 _OutlineColor;struct a2v {float4 vertex : POSITION;float3 normal : NORMAL;}; struct v2f {float4 pos : SV_POSITION;};v2f vert (a2v v) {v2f o;//变化到视角空间是为了让描边在观察空间达到最好的效果float4 pos = mul(UNITY_MATRIX_MV, v.vertex); float3 normal = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal); normal.z = -0.5;pos = pos + float4(normalize(normal), 0) * _Outline;o.pos = mul(UNITY_MATRIX_P, pos);return o;}float4 frag(v2f i) : SV_Target {return float4(_OutlineColor.rgb, 1);}ENDCG}Pass {Tags {"LightMode"="ForwardBase" }//渲染正面Cull BackCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdbase#include "UnityCG.cginc"#include "Lighting.cginc"#include "AutoLight.cginc"#include "UnityShaderVariables.cginc"fixed4 _Color;sampler2D _MainTex;float4 _MainTex_ST;sampler2D _Ramp;fixed4 _Specular;fixed _SpecularScale;struct a2v {float4 vertex : POSITION;float3 normal : NORMAL;float4 texcoord : TEXCOORD0;float4 tangent : TANGENT;}; struct v2f {float4 pos : POSITION;float2 uv : TEXCOORD0;float3 worldNormal : TEXCOORD1;float3 worldPos : TEXCOORD2;SHADOW_COORDS(3)};v2f vert (a2v v) {v2f o;o.pos = UnityObjectToClipPos( v.vertex);o.uv = TRANSFORM_TEX (v.texcoord, _MainTex);o.worldNormal = UnityObjectToWorldNormal(v.normal);o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;TRANSFER_SHADOW(o);return o;}float4 frag(v2f i) : SV_Target {fixed3 worldNormal = normalize(i.worldNormal);fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));fixed3 worldViewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));fixed3 worldHalfDir = normalize(worldLightDir + worldViewDir);fixed4 c = tex2D (_MainTex, i.uv);fixed3 albedo = c.rgb * _Color.rgb;fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);//漫反射系数和阴影值相乘得到最终的漫反射系数fixed diff = dot(worldNormal, worldLightDir);diff = (diff * 0.5 + 0.5) * atten;//对渐变纹理采样并和反射率、光照颜色相乘fixed3 diffuse = _LightColor0.rgb * albedo * tex2D(_Ramp, float2(diff, diff)).rgb;fixed spec = dot(worldNormal, worldHalfDir);fixed w = fwidth(spec) * 2.0; //抗锯齿处理//step是为了_SpecularScale=0时能完全消除高光反射的光照fixed3 specular = _Specular.rgb * lerp(0, 1, smoothstep(-w, w, spec + _SpecularScale - 1)) * step(0.0001, _SpecularScale);return fixed4(ambient + diffuse + specular, 1.0);}ENDCG}}FallBack "Diffuse"}

素描风格渲染

这里不采用mipmap，使用6张素描纹理渲染

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'////// Reference: Praun E, Hoppe H, Webb M, et al. Real-time hatching[C]///Proceedings of the 28th annual conference on Computer graphics and interactive techniques. ACM, 2001: 581.///Shader "Unity Shaders Book/Chapter 14/Hatching" {Properties {_Color ("Color Tint", Color) = (1, 1, 1, 1)_TileFactor ("Tile Factor", Float) = 1 //纹理平铺系数，值越大，素描线条越密_Outline ("Outline", Range(0, 1)) = 0.1//渲染时使用的6张纹理，线条密度一次增大_Hatch0 ("Hatch 0", 2D) = "white" {}_Hatch1 ("Hatch 1", 2D) = "white" {}_Hatch2 ("Hatch 2", 2D) = "white" {}_Hatch3 ("Hatch 3", 2D) = "white" {}_Hatch4 ("Hatch 4", 2D) = "white" {}_Hatch5 ("Hatch 5", 2D) = "white" {}}SubShader {Tags {"RenderType"="Opaque" "Queue"="Geometry"}//必须大写，因为unity会自动把Pass名字转换成大写UsePass "Unity Shaders Book/Chapter 14/Toon Shading/OUTLINE"Pass {Tags {"LightMode"="ForwardBase" }CGPROGRAM#pragma vertex vert#pragma fragment frag #pragma multi_compile_fwdbase#include "UnityCG.cginc"#include "Lighting.cginc"#include "AutoLight.cginc"#include "UnityShaderVariables.cginc"fixed4 _Color;float _TileFactor;sampler2D _Hatch0;sampler2D _Hatch1;sampler2D _Hatch2;sampler2D _Hatch3;sampler2D _Hatch4;sampler2D _Hatch5;struct a2v {float4 vertex : POSITION;float4 tangent : TANGENT; float3 normal : NORMAL; float2 texcoord : TEXCOORD0; };struct v2f {float4 pos : SV_POSITION;float2 uv : TEXCOORD0;//6张纹理的需要6个混合权重，存在两个fixed3中fixed3 hatchWeights0 : TEXCOORD1;fixed3 hatchWeights1 : TEXCOORD2;//阴影效果使用float3 worldPos : TEXCOORD3;SHADOW_COORDS(4)};v2f vert(a2v v) {v2f o;o.pos = UnityObjectToClipPos(v.vertex);//纹理采样坐标o.uv = v.texcoord.xy * _TileFactor;//计算漫反射系数fixed3 worldLightDir = normalize(WorldSpaceLightDir(v.vertex));fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);fixed diff = max(0, dot(worldLightDir, worldNormal));//初始化权重o.hatchWeights0 = fixed3(0, 0, 0);o.hatchWeights1 = fixed3(0, 0, 0);//把diff缩放[0,7],得到hatchFactorfloat hatchFactor = diff * 7.0;//将其分为7个子区间，判断所处区间计算混合权重if (hatchFactor > 6.0) {// Pure white, do nothing} else if (hatchFactor > 5.0) {o.hatchWeights0.x = hatchFactor - 5.0;} else if (hatchFactor > 4.0) {o.hatchWeights0.x = hatchFactor - 4.0;o.hatchWeights0.y = 1.0 - o.hatchWeights0.x;} else if (hatchFactor > 3.0) {o.hatchWeights0.y = hatchFactor - 3.0;o.hatchWeights0.z = 1.0 - o.hatchWeights0.y;} else if (hatchFactor > 2.0) {o.hatchWeights0.z = hatchFactor - 2.0;o.hatchWeights1.x = 1.0 - o.hatchWeights0.z;} else if (hatchFactor > 1.0) {o.hatchWeights1.x = hatchFactor - 1.0;o.hatchWeights1.y = 1.0 - o.hatchWeights1.x;} else {o.hatchWeights1.y = hatchFactor;o.hatchWeights1.z = 1.0 - o.hatchWeights1.y;}o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;TRANSFER_SHADOW(o);return o; }fixed4 frag(v2f i) : SV_Target {//采样并和对应的权重相乘得到每张纹理的采样颜色fixed4 hatchTex0 = tex2D(_Hatch0, i.uv) * i.hatchWeights0.x;fixed4 hatchTex1 = tex2D(_Hatch1, i.uv) * i.hatchWeights0.y;fixed4 hatchTex2 = tex2D(_Hatch2, i.uv) * i.hatchWeights0.z;fixed4 hatchTex3 = tex2D(_Hatch3, i.uv) * i.hatchWeights1.x;fixed4 hatchTex4 = tex2D(_Hatch4, i.uv) * i.hatchWeights1.y;fixed4 hatchTex5 = tex2D(_Hatch5, i.uv) * i.hatchWeights1.z;//计算纯白在渲染中的贡献度，通过1减去所有6张纹理的权重得到。是光照最亮的部分是纯白色fixed4 whiteColor = fixed4(1, 1, 1, 1) * (1 - i.hatchWeights0.x - i.hatchWeights0.y - i.hatchWeights0.z - i.hatchWeights1.x - i.hatchWeights1.y - i.hatchWeights1.z);fixed4 hatchColor = hatchTex0 + hatchTex1 + hatchTex2 + hatchTex3 + hatchTex4 + hatchTex5 + whiteColor;UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);return fixed4(hatchColor.rgb * _Color.rgb * atten, 1.0);}ENDCG}}FallBack "Diffuse"}