Stop projector shader from blending between pixels

Hello,

I am trying to use this following projector for making an overlay over buildings.
The input texture has pixels that represent each game tiles.
The projector shader will shade buildings with color corresponding to the game tile.
The problem I have is with shader blending between pixels as shown in pictures below.
At the joint part, I don't want blue and red to blend into purple.
Is there anyway to fix this?

Shader code is here:

Code (CSharp):

1. Shader "Projector/Overlay Projector"
2. {
3.     Properties
4.     {
5.        _Color ("Main Color", Color) = (1,1,1,1)
6.        _ShadowTex ("Projected Image", 2D) = "white" {}
7.     }
8.  
9.     SubShader
10.     {
11.           Pass
12.           {    
13.           Blend srcalpha OneMinusSrcAlpha
14.           ZWrite Off // don't change depths
15.           Offset -1, -1 // avoid depth fighting
16.  
17.           CGPROGRAM
18.  
19.           #pragma vertex vert
20.           #pragma fragment frag
21.  
22.           uniform sampler2D _ShadowTex;
23.  
24.           // Projector-specific uniforms
25.           uniform float4x4 _Projector; // transformation matrix
26.               // from object space to projector space
27.           struct vertexInput {
28.              float4 vertex : POSITION;
29.              float3 normal : NORMAL;
30.           };
31.  
32.           struct vertexOutput {
33.              float4 pos : SV_POSITION;
34.              float4 posProj : TEXCOORD0;
35.                 // position in projector space
36.           };
37.  
38.           vertexOutput vert(vertexInput input)
39.           {
40.              vertexOutput output;
41.  
42.              output.posProj = mul(_Projector, input.vertex);
43.              output.pos = mul(UNITY_MATRIX_MVP, input.vertex);
44.  
45.              return output;
46.           }
47.  
48.  
49.           float4 frag(vertexOutput input) : COLOR
50.           {
51.              if (input.posProj.w > 0.0) // in front of projector?
52.              {
53.                 return tex2D(_ShadowTex , input.posProj);//.xy / input.posProj.w);
54.                 // alternatively: return tex2Dproj(
55.                 //    _ShadowTex, input.posProj);
56.              }
57.              else // behind projector
58.              {
59.                 return float4(0.0, 0.0, 0.0, 0.0);
60.              }
61.           }
62.  
63.           ENDCG
64.        }
65.     }
66.     // Fallback "Projector/Light"
67. }

Thank you very much in advance

 

Try changing the filter mode of the texture to point.
That will disable bilinear filtering, (blending between pixels).

 

Yes that works!
Thank you very much.