Unity only render objects from a layer inside a 2D mesh

I'm trying to make a 2D top down game with a field of view.

My field of view is shown by a 2D mesh of the fov, not being able to pass through walls.

I need to be able to put some objects such as enemies in a layer that's only rendered when it's inside the view cone.

I was following this tutorial but couldn't find the overwrite setting shown at 18:16 (I believe this is because the LWRP no longer exists in Unity). Are there any alternatives or other solutions?

Solution

if you want to implement it from scratch and WITH BUILT-IN RENDER PIPELINE, you can read along :

lets say this is the scene , the white plane is fov and cubes are enemies:

the fov can have a simple shader. very simple shader. this for example:

Shader "Unlit/simple_shader"
{
    Properties
    {
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                return 1;
            }
            ENDCG
        }
    }
}

Then you'll need a seperate camera to render ONLY the fov mesh and save it as an image, which we know as RenderTexture. which will look like a black and white mask:

then make another camera layer that only renders enemies:

then add the generated mask to it:

then put it on top of the main camera:

here is the sample asset I exported along with the scene: https://usaupload.com/shared/hkcayffn-9psb5e_loknmu3086nnh2--tbk0fm5s8xqj8ilnyok2zklav8-4mk7i8tf1tsjfbstgzrpw3upwi_w2e96k9nqm05-knhk3m_1237myy8nvco910c67afmo