MatrixOperations.cs

//  https://gist.github.com/hecomi/9580605
//Dirctionary:

View Matrix : camera.worldToCameraMatrix


// How to project a texture:
      //cs:
      projectionMatrix = camera.projectionMatrix * camera.worldToCameraMatrix
      //vert:
      o.coords = mul(projectionMatrix, o.worldPos);
      //frag:
      o.coords.xy /= o.coords.w;
      o.coords.xy = (o.coords.xy+1) * 0.5;
      float4 col = tex2D(_MainTex, o.shadowCoords);
      
 // Sampling custom shadow
 
 //cs:
  private readonly ShaderProperty.MatrixValue _spMatrix = new ShaderProperty.MatrixValue("pp_ProjectorMatrix");
        private readonly ShaderProperty.TextureValue _spDepth = new ShaderProperty.TextureValue("pp_DepthProjection");
        private readonly ShaderProperty.VectorValue _spPos = new ShaderProperty.VectorValue("pp_ProjectorPosition");
        private readonly ShaderProperty.VectorValue _spZBuffer = new ShaderProperty.VectorValue("pp_ProjectorClipPrecompute");
        private readonly ShaderProperty.VectorValue _camParams = new ShaderProperty.VectorValue("pp_ProjectorConfiguration");

        private void OnPostRender() {

            if (!_depthCamera) return;

            _spMatrix.GlobalValue = _depthCamera.projectionMatrix * _depthCamera.worldToCameraMatrix;
            _spDepth.GlobalValue = _depthTarget;
            _spPos.GlobalValue = transform.position.ToVector4(0);

            var far = _depthCamera.farClipPlane;
            var near = _depthCamera.nearClipPlane;

            _camParams.GlobalValue = new Vector4(
                _depthCamera.aspect,
                Mathf.Tan(_depthCamera.fieldOfView * Mathf.Deg2Rad * 0.5f),
                near,
                1f/far);
            
            var zBuff = new Vector4(1f - far / near, far / near, 0, 0);
                zBuff.z = zBuff.x / far;
                zBuff.w = zBuff.y / far;

            _spZBuffer.GlobalValue = zBuff;
            
        }
	// Struct:
		float4 worldPos : 	TEXCOORD0; // Make sure it is float4
		float4 shadowCoords : TEXCOORD6;
	
	
  // In Vert:
 o.worldPos = mul(unity_ObjectToWorld, float4(v.vertex.xyz,1.0f));
 o.shadowCoords = mul(pp_ProjectorMatrix, o.worldPos); 
  // In Frag:
  				float camAspectRatio = pp_ProjectorConfiguration.x;
				float camFOVDegrees = pp_ProjectorConfiguration.y;
				float deFar = pp_ProjectorConfiguration.w;

				o.shadowCoords.xy /= o.shadowCoords.w;

				float alpha = max(0, 1 - dot(o.shadowCoords.xy, o.shadowCoords.xy));

				float viewPos = length(float3(o.shadowCoords.xy * camFOVDegrees,1))*camAspectRatio;

				float depth = tex2D(pp_DepthProjection, (o.shadowCoords.xy + 1) * 0.5);

				float dist = viewPos / (pp_ProjectorClipPrecompute.x * (1 - depth) + pp_ProjectorClipPrecompute.y); 

				float True01Range = length(o.worldPos - pp_ProjectorPosition.xyz) * deFar;

				return  max(0, alpha - abs(True01Range - dist) * 100);