【shader】体积光影

来源：互联网发布：必应词典网络连接超时编辑：程序博客网时间：2024/04/28 16:04

最终效果

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思路

为了投影出体积阴影，我们多用一个pass来渲染网格。

网格延伸的方向是灯光的方向。

我们将顶点转换到模型空间，然后计算和灯光的角度进行顶点的偏移。

btw:因为根据顶点偏移，所以不能对断开的顶点进行平滑的过度。

通过点乘插值我们来决定颜色的插值。

该shader不仅可以用来做体积投影，也可以在灯光下做体积光。

源代码

Shader "QQ/LightTrail"{Properties{//_FrontColor("FrontColor",Color) = (0.5,0.5,0.5,1)_BackColor("BackColor",Color) = (0,0,0,1)_LightColor("LightColor",Color) = (1,1,0,1)_MainTex("Texture", 2D) = "white" {}_SmoothRange("SmoothRange",Range(0,20)) = 1_TrailColor("TrailColor",Color) = (0,0,0,1)_TrailPower("TrailPower",Range(0,10)) = 2_TrailLength("TrailLength",Range(0,500)) = 100}SubShader{Tags{ "RenderType" = "Transparent""Queue" = "Transparent" }LOD 100Pass{Tags{ "LightMode" = "ForwardBase" }CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fog#include "UnityCG.cginc"struct a2v{float4 vertex : POSITION;float2 uv : TEXCOORD0;float3 normal:NORMAL;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;float4 wPos:TEXCOORD1;UNITY_FOG_COORDS(2)float3 normal:TEXCOORD3;float2 uv_mask:TEXCOORD4;};uniform float4 _LightColor0;//fixed4 _FrontColor;fixed4 _BackColor;fixed4 _LightColor;sampler2D _MainTex;float4 _MainTex_ST;float _SmoothRange;v2f vert(a2v v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.wPos = mul(unity_ObjectToWorld,v.vertex);_MainTex_ST.zw *= _Time.x;o.uv = TRANSFORM_TEX(v.uv, _MainTex);o.normal = UnityObjectToWorldNormal(v.normal);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag(v2f i) : SV_Target{float nor = dot(i.normal, normalize(UnityWorldSpaceLightDir(i.wPos)));fixed4 col = tex2D(_MainTex, i.uv);float _front = saturate(nor*_SmoothRange);col *= lerp(_BackColor, _LightColor0,_front);col += _LightColor*min(1 - _front,col.a);UNITY_APPLY_FOG(i.fogCoord, col);return col;}ENDCG}Pass{Tags{ "LightMode" = "ForwardBase" }ZWrite OffCull OffBlend SrcAlpha OneMinusSrcAlphaCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fog#include "UnityCG.cginc"struct a2v{float4 vertex : POSITION;float3 normal:NORMAL;};struct v2f{float4 vertex : SV_POSITION;float3 wPos:TEXCOORD1;float3 normal:TEXCOORD2;UNITY_FOG_COORDS(3)};fixed4 _TrailColor;float _TrailPower;float _TrailLength;v2f vert(a2v v){v2f o;o.wPos = mul(unity_ObjectToWorld,v.vertex);o.normal = UnityObjectToWorldNormal(v.normal);v.vertex.xyz += v.normal*0.01;o.vertex = mul(UNITY_MATRIX_M, v.vertex);float3 lightDir = normalize(UnityWorldSpaceLightDir(o.wPos));float NdotL = min(0,dot(o.normal, lightDir.xyz));o.vertex.xyz += lightDir *NdotL* _TrailLength;o.vertex = mul(UNITY_MATRIX_VP, o.vertex);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag(v2f i) : SV_Target{float nor = dot(i.normal, normalize(UnityWorldSpaceLightDir(i.wPos)));fixed4 col = _TrailColor*(pow(1.5*_TrailColor.a - abs(nor), _TrailPower));UNITY_APPLY_FOG(i.fogCoord, col);return col;}ENDCG}Pass{Blend One OneTags{ "LightMode" = "ForwardAdd" }CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fog#include "UnityCG.cginc"struct a2v{float4 vertex : POSITION;float2 uv : TEXCOORD0;float3 normal:NORMAL;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;float4 wPos:TEXCOORD1;UNITY_FOG_COORDS(2)float3 normal:TEXCOORD3;float2 uv_mask:TEXCOORD4;};uniform float4 _LightColor0;//fixed4 _FrontColor;fixed4 _BackColor;fixed4 _LightColor;sampler2D _MainTex;float4 _MainTex_ST;float _SmoothRange;v2f vert(a2v v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.wPos = mul(unity_ObjectToWorld,v.vertex);_MainTex_ST.zw *= _Time.x;o.uv = TRANSFORM_TEX(v.uv, _MainTex);o.normal = UnityObjectToWorldNormal(v.normal);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag(v2f i) : SV_Target{float nor = dot(i.normal, normalize(UnityWorldSpaceLightDir(i.wPos)));fixed4 col = tex2D(_MainTex, i.uv);float _front = saturate(nor*_SmoothRange);col *= lerp(_BackColor, _LightColor0,_front);col += _LightColor*min(1 - _front,col.a);UNITY_APPLY_FOG(i.fogCoord, col);return col;}ENDCG}Pass{Tags{ "LightMode" = "ForwardAdd" }ZWrite OffCull OffBlend SrcAlpha OneMinusSrcAlphaCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fog#include "UnityCG.cginc"struct a2v{float4 vertex : POSITION;float3 normal:NORMAL;};struct v2f{float4 vertex : SV_POSITION;float3 wPos:TEXCOORD1;float3 normal:TEXCOORD2;UNITY_FOG_COORDS(3)};fixed4 _TrailColor;float _TrailPower;float _TrailLength;v2f vert(a2v v){v2f o;o.wPos = mul(unity_ObjectToWorld,v.vertex);o.normal = UnityObjectToWorldNormal(v.normal);v.vertex.xyz += v.normal*0.01;o.vertex = mul(UNITY_MATRIX_M, v.vertex);float3 lightDir = normalize(UnityWorldSpaceLightDir(o.wPos));float NdotL = min(0,dot(o.normal, lightDir.xyz));o.vertex.xyz += lightDir *NdotL* _TrailLength;o.vertex = mul(UNITY_MATRIX_VP, o.vertex);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag(v2f i) : SV_Target{float nor = dot(i.normal, normalize(UnityWorldSpaceLightDir(i.wPos)));fixed4 col = _TrailColor*(pow(1.5*_TrailColor.a - abs(nor), _TrailPower));UNITY_APPLY_FOG(i.fogCoord, col);return col;}ENDCG}}}

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