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" {
  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