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(,)
                    };
   
                    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();
                        #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[].rgb, unity_LightColor[].rgb, unity_LightColor[].rgb, unity_LightColor[].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 * ;
   
                        color += IN.vlight;
   
                        color += _LightColor0.rgb * NdotL * ( atten * );
                        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)