关于Unity动态物体无法向使用使用custom shader和lightmap的物体投射阴影

  最近在做unity shader forge和marmoset的优化，TA那边遇到了一个阴影显示的问题，具体如下：

  在Forward Rendering状态下，静态场景使用了是shader forge生成的blendlayer类的shader，使用lightmap烘培贴图后，动态角色走到静态物体附近时，方向光在角色上的投影，无法投射到使用shader forge材质的物体上，但其他材质和使用marmoset的材质可以正常接收。查询了一些网站解决方案后，最终确定是custom shader 写法的问题，shader forge生成的shader属于自己实现vs和ps的功能，和写surface shader不同，除了着色用的shader pass（"LightMode" = "ForwardBase"）外需要Cast shadow用的第2个pass {"LightMode" = "ForwardAdd"}。

 

下面是一个参考方案的代码

1. "Test" {
       SubShader {
           Tags { "RenderType" = "Opaque"}
   
           // This pass acts the same as the surface shader first pass.
           // Calculates per-pixel the most important directional light with shadows,
           // then per-vertex the next 4 most important lights,
           // then per-vertex spherical harmionics the rest of the lights,
           // and the ambient light value.
    
           Pass {
               Tags {"LightMode" = "ForwardBase"}
               CGPROGRAM
   
                   #pragma multi_compile_fwdbase
                   #pragma vertex vert
                   #pragma fragment frag
                   #pragma fragmentoption ARB_precision_hint_fastest
                   #include "UnityCG.cginc"
                   #include "AutoLight.cginc"
    
                   struct Input
                   {
                       float4 pos : SV_POSITION;
                       float3 vlight : COLOR;
                       float3 lightDir : TEXCOORD1;
                       float3 vNormal : TEXCOORD2;
                       LIGHTING_COORDS(3,4)
                   };
    
                   Input vert(appdata_full v)
                   {
                       Input o;
                       o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                       // Calc normal and light dir.
                       o.lightDir = normalize(ObjSpaceLightDir(v.vertex));
                       o.vNormal = normalize(v.normal).xyz;
    
                       // Calc spherical harmonics and vertex lights. Ripped from compiled surface shader
                       float3 worldPos = mul(_Object2World, v.vertex).xyz;
                       float3 worldNormal = mul((float3x3)_Object2World, SCALED_NORMAL);
                       o.vlight = float3(0);
                       #ifdef LIGHTMAP_OFF
    
                           float3 shlight = ShadeSH9(float4(worldNormal, 1.0));
                           o.vlight = shlight;
                           #ifdef VERTEXLIGHT_ON
                               o.vlight += Shade4PointLights (
    
                                   unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0,
    
                                   unity_LightColor[0].rgb, unity_LightColor[1].rgb, unity_LightColor[2].rgb, unity_LightColor[3].rgb,
    
                                   unity_4LightAtten0, worldPos, worldNormal
    
                                   );
    
                           #endif // VERTEXLIGHT_ON
                       #endif // LIGHTMAP_OFF
                       TRANSFER_VERTEX_TO_FRAGMENT(o);
                       return o;
                   }
    
                   float4 _LightColor0; // Contains the light color for this pass.
   
                   half4 frag(Input IN) : COLOR
                   {
                       IN.lightDir = normalize ( IN.lightDir );
                       IN.vNormal = normalize ( IN.vNormal );
    
                       float atten = LIGHT_ATTENUATION(IN);
                       float3 color;
                       float NdotL = saturate( dot (IN.vNormal, IN.lightDir ));
                       color = UNITY_LIGHTMODEL_AMBIENT.rgb * 2;
    
                       color += IN.vlight;
    
                       color += _LightColor0.rgb * NdotL * ( atten * 2);
                       return half4(color, 1.0f);
                    }
    
               ENDCG
           }
    
           // Take this pass out if you don't want extra per-pixel lights.
           // Just set the other lights' Render Mode to "Not Important",
           // and they will be calculated as Spherical Harmonics or Vertex Lights in the above pass instead.
    
           Pass {
    
               Tags {"LightMode" = "ForwardAdd"}
    
               CGPROGRAM
   
                   #pragma multi_compile_fwdadd
                   #pragma vertex vert
                   #pragma fragment frag
                   #pragma fragmentoption ARB_precision_hint_fastest
                   #include "UnityCG.cginc"
                    #include "AutoLight.cginc"
   
                   struct Input
                   {
                       float4 pos : SV_POSITION;
                       float3 lightDir : TEXCOORD1;
                       float3 vNormal : TEXCOORD2;
                   }; 
    
                   Input vert(appdata_full v)
                    { 
                       Input o;
                       o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
    
                       // Calc normal and light dir.
                       o.lightDir = normalize(ObjSpaceLightDir(v.vertex));
                       o.vNormal = normalize(v.normal).xyz;
    
                       // Don't need any ambient or vertex lights in here as this is just an additive pass for each extra light.
                       // Shadows won't work here, either.
                       return o;
                   }
     
                   float4 _LightColor0; // Contains the light color for this pass.
   
                   half4 frag(Input IN) : COLOR
                   {
                       IN.lightDir = normalize ( IN.lightDir );
                       IN.vNormal = normalize ( IN.vNormal );
                    
                       float3 color;
                       float NdotL = saturate( dot (IN.vNormal, IN.lightDir ));
                       color = _LightColor0.rgb * NdotL;
                       return half4(color, 1.0f); 
                   }
   
               ENDCG
    
           }
       }
    
       FallBack "Diffuse"
    
   }

 

而使用surface shader时候，只需要在声明surface时，设置制定的option（fullforwardshadows）就可以了

1. #pragma surface MarmosetSurfMarmosetDirect vertex:MarmosetVert fullforwardshadows

回过头来说shader forge插件,场景左侧使用sf生成的shader，use lightmap后，实时阴影果断看不到了

 

左边木板为surface shader，右边为VS+PS Shader，阴影无法投射到石头上

 

将shader forge设置为multi-light，他会自动生成ForwardAdd的pass，这样阴影就显示出来了。但照明效果也完全变了样子

 

这个问题，在shader forge的论坛上也有提过，作者也说修改过这个bug了，但实际上最新的0.36还是没有完全解决

 

如果设置ForwardAdd后还没有投影，可以把light的lightmapping 设置为realtimeOnly。或者是再复制一个投影的主光源。

 

结论，Shader forge还是慎用吧，而且shader node也远没有比sky shop这类 uber shader要节省，为了投影，导致使用lightmap和real time的效果差别很大，

完全是得不偿失的。

 

 

 

 

 

 

 

 
 

来自为知笔记(Wiz)