unity在定制的shader里面如何添加阴影

下面这段文字是在unity的官方论坛上发现的，下面的shader已经验证过，可以使用。

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"
    
    
    
    
}