Bicolor viewshed shader

Hi

I'm a total beginner with shader.

What i want to achieve is a shader wich would color any surface hit by light in green, and the other in red.

(Final goal would be to achieve this effect :

So right now i have done that :

Code (CSharp):

1. Shader "Custom/TESTSHADER" {
2.     Properties {
3.         _FirstColor ("First Color", Color) = (1,1,1,1)
4.         _SecondColor("Second Color", Color) = (0,0,0,0)
5.     }
6.     SubShader {
7.         Tags { "RenderType"="Opaque" }
8.         LOD 200
9.  
10.         CGPROGRAM
11.         #pragma surface surf ViewShed
12.  
13.         float4 _FirstColor;
14.         float4 _SecondColor;
15.         float4 c;
16.  
17.         struct Input {
18.             float2 uv_MainTex;
19.         };
20.  
21.         inline float4 LightingViewShed(SurfaceOutput surface, float3 lightDirection, float attenuation) {
22.             float delta = dot(surface.Normal, lightDirection);
23.          
24.             if (delta > 0) {
25.                 c.rgb = _FirstColor.rgb;
26.             }
27.             else {
28.                 c.rgb = _SecondColor.rgb;
29.             }
30.  
31.             c.a = surface.Alpha;
32.             return c;
33.         }
34.  
35.         void surf (Input IN, inout SurfaceOutput surface) {
36.             surface.Albedo = fixed3(1.0, 1.0, 1.0);
37.         }
38.         ENDCG
39.     }
40.     FallBack "Diffuse"
41. }

So basically it is a first try, but the result is not a total crap



However, when using a spotLight instead of directionnal light, it doesn't behave has intended:



There is also the fact that i want to be able see the shadows in red :O

Any help or advices would be so appreciate ! I'm still very far from my final goal :0

 

I am trying to achieve the same behavior have you figured it out?

 

You could get the same effect with two directional lights pointing in opposite directions and with high intensity.