_WorldSpaceLightPos0 giving no position information for point lights.

Hey, I have a question about shader writing in the Cg language.

I'm a little confused as to how this variable(_WorldSpaceLightPos0) works. In the docs, it says that it should return the direction when the light is set to directional, but otherwise, it should return a position.

And the direction works flawlessly. But when I switch my only light in the scene to a point light. I get all 0's as values.

To debug this I simply return the _WorldSpaceLightPos0 in my fragment function. If it's a directional light, I get colors, representing the direction. If it's a point light, I get just black, no matter where I move the light.

I'm lost and have no idea how to fix this. Maybe I'm missing a line of code or something.

Here's the full code for proof.

Code (CSharp):

1. Shader "ShaderTest/LitBlinnPhong"
2. {
3.     Properties
4.     {
5.         _MainTex("Texture", 2D) = "white" {}
6.         _SurfaceColor("Surface Color", Color) = (1,1,1,1)
7.         _Ambient("Ambient Light", Color) = (0,0,0,0)
8.         _Gloss("Glossiness", Range(1, 10)) = 1
9.         _RimPower("Rim Light", Range(0,1)) = 1
10.         _Point("Point", Vector) = (0,0,0,0)
11.     }
12.         SubShader
13.         {
14.             Tags { "RenderType" = "Opaque" }
15.             LOD 100
16.  
17.             Pass
18.             {
19.                 Tags { "LightMode" = "ForwardBase" }
20.                 CGPROGRAM
21.                 #pragma vertex vert
22.                 #pragma fragment frag
23.  
24.                 #include "UnityCG.cginc"
25.                 #include "UnityLightingCommon.cginc"
26.  
27.                 float _Gloss;
28.                 float _RimPower;
29.                 float4 _SurfaceColor;
30.                 float4 _Ambient;
31.                 float4 _Point;
32.  
33.                 struct appdata
34.                 {
35.                     float4 vertex : POSITION;
36.                     float3 normal : NORMAL;
37.                     float2 uv : TEXCOORD0;
38.                 };
39.  
40.                 struct v2f
41.                 {
42.                     float4 vertex : SV_POSITION;
43.                     float3 worldNormal : COLOR0;
44.                     float3 viewDir : COLOR1;
45.                     float2 uv : TEXCOORD0;
46.                 };
47.  
48.                 v2f vert(appdata v)
49.                 {
50.                     v2f o;
51.  
52.                     o.vertex = UnityObjectToClipPos(v.vertex);
53.                     o.worldNormal = UnityObjectToWorldNormal(v.normal);
54.                     o.viewDir = WorldSpaceViewDir(v.vertex);
55.                     return o;
56.                 }
57.  
58.                 fixed4 frag(v2f i) : SV_Target
59.                 {
60.  
61.                     float4 lightCol = _LightColor0;
62.  
63.                     float3 n = normalize(i.worldNormal);
64.                     float3 v = normalize(i.viewDir);
65.                     float3 l = _WorldSpaceLightPos0.xyz;
66.                     float3 r = reflect(-l, n);
67.                     float3 h = normalize(l + v);
68.  
69.                     float3 lambert = float3(0, 0, 0);
70.                     float3 blinn = float3(0, 0, 0);
71.                     float3 fresnel = float3(0, 0, 0);
72.  
73.                     float lightDist = 1 - distance(_Point, i.worldNormal);
74.                     float atten = 1.0;
75.  
76.                     float gloss = _Gloss * _Gloss;
77.                     float roughness = _Gloss / 10;
78.  
79.                     if (_WorldSpaceLightPos0.w == 0)
80.                     {
81.                         lambert = clamp(dot(n, l), 0, 1);
82.                         blinn = pow(max(0, dot(h, n)), gloss) * lambert;
83.                         fresnel = clamp(1 - pow(dot(n, v), 0.5), 0, 1) * lambert;
84.                     }
85.                     else
86.                     {
87.                         //lightDist = distance(n, l);
88.                         //atten = 1 / lightDist;
89.  
90.                         //lambert = atten;
91.                     }
92.  
93.                     float4 lambertLight = float4(lambert, 1) * _SurfaceColor;
94.                     float4 blinnLight = float4(blinn, 1);
95.                     float4 fresnelLight = float4(fresnel, 1) * _RimPower * roughness;
96.  
97.                     //float4 light = (blinnLight + lambertLight + fresnelLight) * lightCol;
98.                     float4 light = float4(lambert, 1);
99.  
100.                     float4 color = float4(1, 1, 1, 1);
101.  
102.                     float4 col = color * lightDist;
103.                     return _WorldSpaceLightPos0;
104.                 }
105.  
106.                 ENDCG
107.             }
108.         }
109. }
110.  

 

did you solve the bug?

 

In this thread bgolus writes

Also if "LightMode"="ForwardBase" is true then the _WorldSpaceLightPos0 is always for a directional light, even if none exists in the scene. Only "LightMode"="ForwardAdd" has support for passing the position of point lights.

 

Is your light baked?