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.   1 "Test" {
     2     SubShader {
     3         Tags { "RenderType" = "Opaque"}
     4 
     5         // This pass acts the same as the surface shader first pass.
     6         // Calculates per-pixel the most important directional light with shadows,
     7         // then per-vertex the next 4 most important lights,
     8         // then per-vertex spherical harmionics the rest of the lights,
     9         // and the ambient light value.
    10  
    11         Pass {
    12             Tags {"LightMode" = "ForwardBase"}
    13             CGPROGRAM
    14 
    15                 #pragma multi_compile_fwdbase
    16                 #pragma vertex vert
    17                 #pragma fragment frag
    18                 #pragma fragmentoption ARB_precision_hint_fastest
    19                 #include "UnityCG.cginc"
    20                 #include "AutoLight.cginc"
    21  
    22                 struct Input
    23                 {
    24                     float4 pos : SV_POSITION;
    25                     float3 vlight : COLOR;
    26                     float3 lightDir : TEXCOORD1;
    27                     float3 vNormal : TEXCOORD2;
    28                     LIGHTING_COORDS(3,4)
    29                 };
    30  
    31                 Input vert(appdata_full v)
    32                 {
    33                     Input o;
    34                     o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
    35                     // Calc normal and light dir.
    36                     o.lightDir = normalize(ObjSpaceLightDir(v.vertex));
    37                     o.vNormal = normalize(v.normal).xyz;
    38  
    39                     // Calc spherical harmonics and vertex lights. Ripped from compiled surface shader
    40                     float3 worldPos = mul(_Object2World, v.vertex).xyz;
    41                     float3 worldNormal = mul((float3x3)_Object2World, SCALED_NORMAL);
    42                     o.vlight = float3(0);
    43                     #ifdef LIGHTMAP_OFF
    44  
    45                         float3 shlight = ShadeSH9(float4(worldNormal, 1.0));
    46                         o.vlight = shlight;
    47                         #ifdef VERTEXLIGHT_ON
    48                             o.vlight += Shade4PointLights (
    49  
    50                                 unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0,
    51  
    52                                 unity_LightColor[0].rgb, unity_LightColor[1].rgb, unity_LightColor[2].rgb, unity_LightColor[3].rgb,
    53  
    54                                 unity_4LightAtten0, worldPos, worldNormal
    55  
    56                                 );
    57  
    58                         #endif // VERTEXLIGHT_ON
    59                     #endif // LIGHTMAP_OFF
    60                     TRANSFER_VERTEX_TO_FRAGMENT(o);
    61                     return o;
    62                 }
    63  
    64                 float4 _LightColor0; // Contains the light color for this pass.
    65 
    66                 half4 frag(Input IN) : COLOR
    67                 {
    68                     IN.lightDir = normalize ( IN.lightDir );
    69                     IN.vNormal = normalize ( IN.vNormal );
    70  
    71                     float atten = LIGHT_ATTENUATION(IN);
    72                     float3 color;
    73                     float NdotL = saturate( dot (IN.vNormal, IN.lightDir ));
    74                     color = UNITY_LIGHTMODEL_AMBIENT.rgb * 2;
    75  
    76                     color += IN.vlight;
    77  
    78                     color += _LightColor0.rgb * NdotL * ( atten * 2);
    79                     return half4(color, 1.0f);
    80                  }
    81  
    82             ENDCG
    83         }
    84  
    85         // Take this pass out if you don't want extra per-pixel lights.
    86         // Just set the other lights' Render Mode to "Not Important",
    87         // and they will be calculated as Spherical Harmonics or Vertex Lights in the above pass instead.
    88  
    89         Pass {
    90  
    91             Tags {"LightMode" = "ForwardAdd"}
    92  
    93             CGPROGRAM
    94 
    95                 #pragma multi_compile_fwdadd
    96                 #pragma vertex vert
    97                 #pragma fragment frag
    98                 #pragma fragmentoption ARB_precision_hint_fastest
    99                 #include "UnityCG.cginc"
   100                  #include "AutoLight.cginc"
   101 
   102                 struct Input
   103                 {
   104                     float4 pos : SV_POSITION;
   105                     float3 lightDir : TEXCOORD1;
   106                     float3 vNormal : TEXCOORD2;
   107                 }; 
   108  
   109                 Input vert(appdata_full v)
   110                  { 
   111                     Input o;
   112                     o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
   113  
   114                     // Calc normal and light dir.
   115                     o.lightDir = normalize(ObjSpaceLightDir(v.vertex));
   116                     o.vNormal = normalize(v.normal).xyz;
   117  
   118                     // Don't need any ambient or vertex lights in here as this is just an additive pass for each extra light.
   119                     // Shadows won't work here, either.
   120                     return o;
   121                 }
   122   
   123                 float4 _LightColor0; // Contains the light color for this pass.
   124 
   125                 half4 frag(Input IN) : COLOR
   126                 {
   127                     IN.lightDir = normalize ( IN.lightDir );
   128                     IN.vNormal = normalize ( IN.vNormal );
   129                  
   130                     float3 color;
   131                     float NdotL = saturate( dot (IN.vNormal, IN.lightDir ));
   132                     color = _LightColor0.rgb * NdotL;
   133                     return half4(color, 1.0f); 
   134                 }
   135 
   136             ENDCG
   137  
   138         }
   139     }
   140  
   141     FallBack "Diffuse"
   142  
   143 }

    

 

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)