长沙网站建计,公司搜索seo,a5站长网,镇江丹阳建设局网站阴影生成原理 以平行光为例#xff0c;把相机移动到光源位置#xff0c;计算阴影映射纹理#xff08;shadowmap#xff09;#xff0c;这张shadowmap本质上是一张深度图#xff0c;它记录了从该光源的位置出发、能看到的场景中距离它最近的表面位置#xff08;深度信息把相机移动到光源位置计算阴影映射纹理shadowmap这张shadowmap本质上是一张深度图它记录了从该光源的位置出发、能看到的场景中距离它最近的表面位置深度信息。渲染时中把顶点位置变换到光源空间下得到它在光源空间中的三维位置信息。然后我们使用xy分量对shadowmap进行采样得到shadowmap中该位置的深度信息。如果该深度值小于该顶点的深度值通常由z分量得到那么说明该点位于阴影中。如图将顶点P转换到光源空间得到Px, Py, PzPz 0.9用Px, Py对shadowmap采样得到C点的深度0.40.4 0.9所以P点在阴影中
需要注意的细节
使用内置阴影的shader大致框架如下这里略去一些不重要的部分
Shader MyCustom/BuildinShadow
{Properties{}SubShader{Tags { RenderTypeOpaque }Pass{Tags {LightModeForwardBase}CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdbase#include UnityCG.cginc#include Lighting.cginc#include AutoLight.cgincstruct appdata{float4 vertex : POSITION;};struct v2f{float4 pos : SV_POSITION;SHADOW_COORDS(x) //x表示第几个纹理};v2f vert (appdata v){v2f o;//...TRANSFER_SHADOW(o);return o;}fixed4 frag (v2f i) : SV_Target{//...//fixed atten 1.0;//fixed shadow SHADOW_ATTENUATION(i);//return fixed4(ambient (diffuse specular) * atten * shadow, 1.0);UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);return fixed4(ambient (diffuse specular) * atten, 1.0);}ENDCG}Pass{Tags {LightModeForwardAdd}Blend One OneCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdadd// #pragma multi_compile_fwdadd_fullshadows#include UnityCG.cginc#include Lighting.cginc#include AutoLight.cgincstruct appdata{float4 vertex : POSITION;};struct v2f{float4 pos : SV_POSITION;SHADOW_COORDS(x) //x表示第几个纹理};v2f vert (appdata v){v2f o;//...TRANSFER_SHADOW(o);return o;}fixed4 frag (v2f i) : SV_Target{//...UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);return fixed4((diffuse specular) * atten, 1.0);}ENDCG}// 自己实现阴影额外添加一个Pass这个Pass是为了更新光源的阴影映射纹理//Pass//{// Tags {LightModeShadowCaster}//}}Fallback Specular
}需要注意的细节
光源设置阴影类型Hard Shadows或者Soft Shadows物体的Mesh Renderer上设置Cast Shadows和Receive ShadoesPlane或一些半透明物体需要设置双面投射阴影即Cast Shadows设置为Two Sided使用内置阴影需要在shader结尾加上 Fallback “Specular”Specular的Fallback调用了VertexLitVertexLit中有个Pass渲染光源的阴影映射纹理或是摄像机的深度纹理。如果要自己实现阴影需要额外写一个Pass并把LightMode设置为ShadowCasterBase Pass计算平行光和环境光申明编译指令#pragma multi_compile_fwdbaseAdditional Pass计算其他类型的光源如果点光源或聚光灯也要计算阴影需要申明编译指令#pragma multi_compile_fwdadd_fullshadows 代替 #pragma multi_compile_fwdaddAdditional Pass需要设置混合 Blend One One引用内置文件 #include “AutoLight.cginc”计算阴影时所用的宏都是在这个文件中声明的SHADOW_COORDSTRANSFER_SHADOW和SHADOW_ATTENUATION这三个宏是计算阴影时的“三剑客”SHADOW_COORDS就是声明一个用于对阴影纹理采样的坐标TRANSFER_SHADOW将顶点从模型空间转换到光源空间后存储到_ShadowCoord中SHADOW_ATTENUATION使用阴影坐标采样阴影贴图也可以使用UNITY_LIGHT_ATTENUATION代替SHADOW_ATTENUATION它用于计算光照衰减和阴影接受3个参数将光照衰减和阴影值相乘后的结果存储到第一个参数中使用UNITY_LIGHT_ATTENUATION使得Base Pass和Additional Pass的代码得以统一这些宏中会使用上下文变量来进行计算所以变量名称需要和宏中使用的名称一致a2v或appdata结构体中的顶点坐标变量名必须是vertex顶点着色器的输入结构体a2v或appdata必须命名为vv2f中的顶点位置变量必须命名为pos
完整的Shader
Shader MyCustom/BuildinShadow
{Properties{_MainTex (Texture, 2D) white {}_Diffuse (Diffuse, Color) (0.5, 0.5, 0.5, 1)_Specular (Specular, Color) (1, 1, 1, 1)_SpecularPower (SpecularPower, Range(0, 150)) 20_SpecularIntensity (SpecularIntensity, Range(0, 10)) 1.5}SubShader{CGINCLUDEfloat _specular(float3 worldViewDir, float3 worldLightDir, float3 worldNormal, float power, float intensity){float3 halfVector normalize(worldLightDir worldViewDir);float hdotn max(0, dot(halfVector, worldNormal));float specular pow(hdotn, power) * intensity;return specular;}ENDCGTags { RenderTypeOpaque }LOD 100Pass{Tags {LightModeForwardBase}CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdbase#include UnityCG.cginc#include Lighting.cginc#include AutoLight.cgincstruct appdata{float4 vertex : POSITION;float3 normal : NORMAL;float2 uv : TEXCOORD0;};struct v2f{float4 pos : SV_POSITION;float2 uv : TEXCOORD0;float3 worldNormal : TEXCOORD1;float3 worldPos : TEXCOORD2;SHADOW_COORDS(3)};sampler2D _MainTex;float4 _MainTex_ST;float4 _Diffuse;float4 _Specular;float _SpecularPower;float _SpecularIntensity;v2f vert (appdata v){v2f o;o.pos UnityObjectToClipPos(v.vertex);o.uv TRANSFORM_TEX(v.uv, _MainTex);o.worldNormal UnityObjectToWorldNormal(v.normal);o.worldPos mul(unity_ObjectToWorld, v.vertex).xyz;TRANSFER_SHADOW(o);return o;}fixed4 frag (v2f i) : SV_Target{float3 worldLightDir UnityWorldSpaceLightDir(i.worldPos);float3 worldViewDir normalize(UnityWorldSpaceViewDir(i.worldPos));fixed4 texColor tex2D(_MainTex, i.uv);fixed3 albedo texColor.rgb * _Diffuse.rgb;// 环境光float3 ambient UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;// 漫反射float3 diffuse _LightColor0.rgb * albedo * max(0, dot(i.worldNormal, worldLightDir));// 高光float3 specular _LightColor0.rgb * _Specular.rgb * _specular(worldViewDir, worldLightDir, i.worldNormal, _SpecularPower, _SpecularIntensity);// atten为阴影和衰减的乘积UNITY_LIGHT_ATTENUATION针对不同类型的光源进行计算UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);float4 finalColor 1;finalColor.rgb ambient (diffuse specular) * atten;return finalColor;}ENDCG}Pass{Tags {LightModeForwardAdd}Blend One OneCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdadd// 其他光源使用阴影使用下面的指令替换掉 multi_compile_fwdadd// #pragma multi_compile_fwdadd_fullshadows#include UnityCG.cginc#include Lighting.cginc#include AutoLight.cgincstruct appdata{float4 vertex : POSITION;float3 normal : NORMAL;float2 uv : TEXCOORD0;};struct v2f{float4 vertex : SV_POSITION;float2 uv : TEXCOORD0;float3 worldNormal : TEXCOORD1;float3 worldPos : TEXCOORD2;SHADOW_COORDS(3)};sampler2D _MainTex;float4 _MainTex_ST;float4 _Diffuse;float4 _Specular;float _SpecularPower;float _SpecularIntensity;v2f vert (appdata v){v2f o;o.vertex UnityObjectToClipPos(v.vertex);o.uv TRANSFORM_TEX(v.uv, _MainTex);o.worldNormal UnityObjectToWorldNormal(v.normal);o.worldPos mul(unity_ObjectToWorld, v.vertex).xyz;TRANSFER_SHADOW(o);return o;}fixed4 frag (v2f i) : SV_Target{float3 worldLightDir UnityWorldSpaceLightDir(i.worldPos);float3 worldViewDir normalize(UnityWorldSpaceViewDir(i.worldPos));// 漫反射float3 diffuse _LightColor0.rgb * _Diffuse.rgb * max(0, dot(i.worldNormal, worldLightDir));// 高光float3 specular _LightColor0.rgb * _Specular.rgb * _specular(worldViewDir, worldLightDir, i.worldNormal, _SpecularPower, _SpecularIntensity);UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);float4 finalColor 1;finalColor.rgb (diffuse specular) * atten;return finalColor;}ENDCG}}Fallback Specular
}通过Frame Debug观察阴影的渲染过程UpdateDepthTexture即更新摄像机的深度纹理RenderShadowmap即渲染得到平行光的阴影映射纹理CollectShadows即根据深度纹理和阴影映射纹理得到屏幕空间的阴影图最后绘制渲染结果
透明物体的阴影 需要注意的细节
Tags设置 “Queue”“AlphaTest” “RenderType”“TransparentCutout”Cull Off 关闭剔除FallBack “Transparent/Cutout/VertexLit” 它含有透明度测试功能的ShadowCaster Pass为了保证命名统一必须使用_Cutoff来命名透明度阈值Mesh Renderer组件中的Cast Shadows属性设置为Two Sided强制Unity在计算阴影映射纹理时计算所有面的深度信息
完整的shader
Shader MyCustom/AlphaTestShadow
{Properties {_MainTex (Main Tex, 2D) white {}_Color (Color Color, Color) (1, 1, 1, 1)_Cutoff (Alpha Cutoff, Range(0, 1)) 0.5}SubShader {Tags { QueueAlphaTest IgnoreProjectorTrue RenderTypeTransparentCutout }Pass {Tags { LightModeForwardBase }Cull OffCGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile_fwdbase#include Lighting.cginc#include AutoLight.cgincsampler2D _MainTex;float4 _MainTex_ST;fixed4 _Color;fixed _Cutoff;struct a2v{float4 vertex : POSITION;float3 normal : NORMAL;float4 uv : TEXCOORD0;};struct v2f{float4 pos : SV_POSITION;float3 worldNormal : TEXCOORD0;float3 worldPos : TEXCOORD1;float2 uv : TEXCOORD2;SHADOW_COORDS(3)};v2f vert(a2v v){v2f o;o.pos UnityObjectToClipPos(v.vertex);o.worldNormal UnityObjectToWorldNormal(v.normal);o.worldPos mul(unity_ObjectToWorld, v.vertex).xyz;o.uv TRANSFORM_TEX(v.uv, _MainTex);TRANSFER_SHADOW(o);return o;}fixed4 frag(v2f i) : SV_Target{fixed3 worldLightDir normalize(UnityWorldSpaceLightDir(i.worldPos));fixed4 texColor tex2D(_MainTex, i.uv);clip(texColor.a - _Cutoff);fixed3 albedo texColor.rgb * _Color.rgb;// 环境光fixed3 ambient UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;// 漫反射fixed3 diffuse _LightColor0.rgb * albedo * max(0, dot(i.worldNormal, worldLightDir));UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);return fixed4(ambient diffuse * atten, 1.0);}ENDCG}}FallBack Transparent/Cutout/VertexLit
}参考
《Shader 入门精要》 查看Build-in Shaders 需要科学上网
