Trying to make a raymarching shader

I'm trying to make a raymarching shader in unity thats currently only meant to display a simple circle. But for some reason it just doesn't want to work and is only showing the background colour i set. Dies anybody have any reason why this is?

 Shader "Unlit/RayMarcher"
 {
     Properties
     {
         _MainTex ("Texture", 2D) = "white" {}
         _MaxMarchSteps ("Max Marching Steps", int) = 255
         _Epsilion ("Epsilion", float) = 0.001
         _Pos ("Position", Vector) = (0.0,0.0,-5.0)
 
     }
     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;
                 float3 ro : TEXCOORD1;
                 float3 hitPos : TEXCOORD2;
             };
 
             sampler2D _MainTex;
             float4 _MainTex_ST;
 
             float _MaxMarchSteps;
             float _Epsilion;
             float minDist = 0.0;
             float maxDist = 1000.0;
             float3 _Pos;
 
             float sphereSDF(float3 p){
                 return length(p) - 1.0;
             }
 
             float sceneSDF(float3 p){
                 return sphereSDF(p);
             }
 
             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);
                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                 o.ro = mul(unity_WorldToObject, float4(_WorldSpaceCameraPos, 1));
                 o.hitPos = v.vertex;
                 return o;
             }
 
             float getDist(float3 cam, float3 dir, float start, float end){
                 float depth = start;
                 for(int i = 0; i < _MaxMarchSteps; i++){
                     float dist = sceneSDF(cam + depth * dir);
                     if(dist < _Epsilion){
                         return depth;
                     }
                     depth += dist;
                     if(depth >= end)
                         return end;
                 }
                 return end;
             }
 
             float3 rayDir(float FOV, float2 resolution, float2 fragCoord){
                 float2 xy = fragCoord - resolution / 2.0;
                 float z = resolution.y / tan(radians(FOV) / 2.0);
                 return normalize(float3(xy, -z));
             }
 
             fixed4 frag (v2f i) : SV_Target
             {
                 float2 resolution = float2(1920,1080);
                 float3 dir = rayDir(45, resolution, i.uv);
                 float3 camPos = _Pos;
                 float dist = getDist(camPos, dir, 0, 1000);
                 
                 if(dist > maxDist - _Epsilion){
                     return fixed4(0.0, 0.0, 0.0, 1.0);
                 }
 
                 return fixed4(1.0, 0.0, 0.0, 1.0);
             }
             ENDCG
         }
     }
 }