Crepuscupular CS Script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(Camera))]
[AddComponentMenu("Effects/Crepuscular Rays", -1)]
public class Crepuscular : MonoBehaviour
{

    public Material material;
    public GameObject mainLight;
    public RenderTexture stencilRT;
    static readonly int blurTexString = Shader.PropertyToID("_BlurTex");
    static readonly int cosAngle = Shader.PropertyToID("_CosAngle");
    [Range(0, 20)]
    public int blurSize = 3;
    [Range(1, 16)]
    public int resolutionDivisor = 1;

    public static readonly int LightPos = Shader.PropertyToID("_LightPos");
    public Vector4 lightVector;
    private static readonly int Parameter = Shader.PropertyToID("_Parameter");
    public float cosineAngle;

    // Start is called before the first frame update
    void Start()
    {

    }

    void Update()
    {
        var getAngle = material.GetFloat(cosAngle);
        cosineAngle = getAngle;
    }

    private void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        var blurTex = RenderTexture.GetTemporary(256, 128, 0, source.format);
        lightVector =GetComponent<Camera>().WorldToViewportPoint(transform.position - mainLight.transform.forward);
        material.SetVector(LightPos, lightVector);
        Graphics.Blit(source, blurTex, material, 0);
        material.SetTexture(blurTexString, blurTex);

        float widthMod = 1.0f / resolutionDivisor;
//only execute this block if blurSize is > 0, otherwise we will skip this RT and two SGX blur passes (horiz/vert) in the shader
    if (blurSize > 0){
        for(int i = 0; i < 1; i++) {
                float iterationOffs = (i*1.0f);
                material.SetVector (Parameter, new Vector4 (blurSize * widthMod + iterationOffs, -blurSize * widthMod - iterationOffs, 0.0f, 0.0f));

                // vertical blur
                RenderTexture rt2 = RenderTexture.GetTemporary(256, 128, 0, source.format);
                rt2.filterMode = FilterMode.Bilinear;
                Graphics.Blit (blurTex, rt2, material, 1);
                RenderTexture.ReleaseTemporary (blurTex);
                blurTex = rt2;

                // horizontal blur
                rt2 = RenderTexture.GetTemporary(256, 128, 0, source.format);
                rt2.filterMode = FilterMode.Bilinear;
                Graphics.Blit (blurTex, rt2, material, 2);
                RenderTexture.ReleaseTemporary (blurTex);
                blurTex = rt2;
        }
    }
        RenderTexture.ReleaseTemporary(blurTex);
        Graphics.Blit(source, destination, material, 3);
    }
}