ModifyProjectionMatrix.cs

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

public class ModifyProjectionMatrix : MonoBehaviour {

    public Camera camera;
    public Matrix4x4 currentMatrix;
    public Matrix4x4 newMatrix;

	// Use this for initialization
    void Start () {
        camera = GetComponent<Camera>();
        
        currentMatrix = camera.projectionMatrix;
        newMatrix = modifyProjection(currentMatrix, newMatrix);
        camera.projectionMatrix = newMatrix;

     }
	
    Matrix4x4 modifyProjection(Matrix4x4 mat, Matrix4x4 matOut)
    {
        Debug.Log("Generating new matrix");
        //get current near and far
        float k = (mat[10] - 1.0f) / (mat[10] + 1.0f);
        float near = (mat[14] * (1.0f - k)) / (2.0f * k);
        float far = k * near;

        //extract constants
        float n2 = (near + near);
        float diffNF = (near - far);
        float diffRL = n2 / mat[0];
        float diffTB = n2 / mat[5];
        float sumRL = mat[8] * diffRL;
        float sumTB = mat[9] * diffTB;
        float sumNF = mat[10] * diffNF;

        //New near and far plane
        float newNear = 0.011f;
        float newFar = 100.0f;


        sumNF = (newNear + newFar);
        diffNF = (newNear - newFar);
        n2 = (newNear + newNear);
        float factor = newNear / near;
        diffRL *= factor;
        diffTB *= factor;
        sumRL *= factor;
        sumTB *= factor;

        matOut = new Matrix4x4();
        //generate the new matrix
        matOut[0] = n2 / diffRL;
        matOut[1] = 0.0f;
        matOut[2] = 0.0f;
        matOut[3] = 0.0f;

        matOut[4] = 0.0f;
        matOut[5] = n2 / diffTB;
        matOut[6] = 0.0f;
        matOut[7] = 0.0f;

        matOut[8] = sumRL / diffRL;
        matOut[9] = sumTB / diffTB;
        matOut[10] = sumNF / diffNF;
        matOut[11] = -1.0f;

        matOut[12] = 0.0f;
        matOut[13] = 0.0f;
        matOut[14] = (n2 / diffNF) * newFar;
        matOut[15] = 0.0f;
        Debug.Log(matOut);
        return matOut;
    }
}