添加实时阴影

For the sake of anyone else who is trying to write a fragment shader that receives shadows, I figured it out.

You must do these things:

1. '#include "AutoLight.cginc"'
2. '#include "Lighting.cginc"'
3. Add "Tags {"LightMode" = "ForwardBase"}
4. '#pragma multi_compile_fwdbase'
5. Add the Unity macros to your VSOut struct, VS and PS: LIGHTING_COORDS, TRANSFER_VERTEX_TO_FRAGMENT, LIGHT_ATTENUATION.

None of this is documented in the Unity manual.

To access the primary directional light color, unity_LightColor[0] works as long as you don't add "Tags {"LightMode" = "ForwardBase"}". If you do add that line, then it doesn't work: use _LightColor0.rgb instead. Why? Who knows.. probably makes sense to someone with access to the Unity source code. Which means no one.

Good luck!

-Peter

Shader "Custom/PeterShader2" {
Properties
{
    _MainTex ("Base (RGB)", 2D) = "white" {}
}
 
CGINCLUDE
 
#include "UnityCG.cginc"
#include "AutoLight.cginc"
#include "Lighting.cginc"
 
uniform sampler2D _MainTex;
 
ENDCG
 
SubShader
{
    Tags { "RenderType"="Opaque" }
    LOD 200
 
    Pass
    {
       Lighting On
 
       Tags {"LightMode" = "ForwardBase"}
 
       CGPROGRAM
 
       #pragma vertex vert
       #pragma fragment frag
       #pragma multi_compile_fwdbase
 
       struct VSOut
       {
         float4 pos     : SV_POSITION;
         float2 uv       : TEXCOORD1;
         LIGHTING_COORDS(3,4)
       };
 
       VSOut vert(appdata_tan v)
       {
         VSOut o;
         o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
         o.uv = v.texcoord.xy;
 
         TRANSFER_VERTEX_TO_FRAGMENT(o);
 
         return o;
       }
 
       float4 frag(VSOut i) : COLOR
       {
         float3 lightColor = _LightColor0.rgb;
         float3 lightDir = _WorldSpaceLightPos0;
         float4 colorTex = tex2D(_MainTex, i.uv.xy * float2(25.0f));
         float  atten = LIGHT_ATTENUATION(i);
         float3 N = float3(0.0f, 1.0f, 0.0f);
         float  NL = saturate(dot(N, lightDir));
 
         float3 color = colorTex.rgb * lightColor * NL * atten;
         return float4(color, colorTex.a);
       }
 
       ENDCG
    }
} 
FallBack "Diffuse"
}