Create a screen shatter effect

EDIT: SOLUTION FOUND - But still looking for optimizations / suggestions

Through many hours of tinkering and cursing the lack of Shader documentation for Unity I finally achieved what I was looking for.

I have removed all obsolete code from this thread and also included the up-to-date, working shader code + complementing C# code. It's not perfect by any means (I could probably shift all the transformations into a single matrix but instead I manually move one of the internal positions to satisfy the screen ratio adjustment. The whole process is probably wrong, as I recon I should have passed in screen space positions originally instead of passing in NDC's from the start.

SHADER - Code commented out is for calculating and rendering edges, but this looks crap

 Shader "J/Shatter"
 {
     Properties
     {
         _MainTex ("Texture", 2D) = "white" {}
     }
         SubShader
     {
         Tags
         {
             "Queue" = "Overlay"
         }
 
         Cull Off ZWrite Off ZTest Always
         Blend SrcAlpha OneMinusSrcAlpha
 
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
 
             #include "UnityCG.cginc"
 
             struct appdata
             {
                 float4 vertex : POSITION;
                 float2 uv : TEXCOORD0;
                 float4 vbc : TEXCOORD2;
             };
         
             half _ScreenRatio;
 
             struct v2f
             {
                 float2 uv : TEXCOORD0;
                 float4 vertex : SV_POSITION;
                 float4 vbc : TEXCOORD2;
             };
 
             v2f vert (appdata v)
             {
                 v2f o;
 
                 // write vertex data to local var
                 o.vertex = v.vertex;
 
                 // adjust x to compensate for screen ratio
                 o.vertex.x = o.vertex.x * _ScreenRatio;
 
                 // transform vertex
                 o.vertex.xyz = UnityObjectToViewPos(o.vertex);
 
                 // revert x value to NDCs
                 o.vertex.x = o.vertex.x / _ScreenRatio;
 
                 // update barycentric coord
                 o.vbc = v.vbc;
                 
                 // I don't know why this works but this prevents clipping when rotating 
                 o.vertex.z = 0;
 
                 // Pass in uv coords
                 o.uv = v.uv;
 
                 return o;
             }
             
             sampler2D _MainTex;
             
             half _Alpha;
 
             fixed4 frag (v2f i) : SV_Target
             {
                 //i.vbc.b = (1 - i.vbc.r - i.vbc.g);
                 //half3 a3 = i.vbc;
 
                 //half3 d = fwidth(i.vbc);
                 //half3 a3 = smoothstep(half3(0, 0, 0), d * 3, i.vbc);
                 //half minimum = min(min(a3.x, a3.y), a3.z);
 
                 fixed4 col = tex2D(_MainTex, i.uv);
 
                 //col = lerp(col, fixed4(1, 1, 1, 1), 1 - minimum);
 
                 col.a = _Alpha;
 
                 return col;
             }
             ENDCG
         }
     }
 }
 

C#- Code commented out is for calculating and rendering edges, but this looks crap

     IEnumerator RenderTriangles()
     {
         if (m_tex == null) yield return null;
 
         float offset = 0;
         float alpha = 1;
         float rotation = 0;
         float transformDelay = 0.5f;
         float transitionTime = 0;
 
         while (alpha > 0)
         {
             yield return new WaitForEndOfFrame();
 
             if (!m_underlayEnabled)
             {
                 GameManager.EnableLoadingScreen();
                 m_underlayEnabled = true;
 
                 Time.timeScale = 1;
             }
 
             if (!m_mat)
             {
                 var shader = Shader.Find("J/Shatter");
                 m_mat = new Material(shader);
                 m_mat.hideFlags = HideFlags.HideAndDontSave;
 
                 m_mat.mainTexture = m_tex;
             }
 
             GL.LoadOrtho();
             m_mat.SetPass(0);
 
             var screenratio = (float)Screen.width / Screen.height;
             m_mat.SetFloat("_ScreenRatio", screenratio);
             m_mat.SetFloat("_Alpha", alpha);
 
             for (int i = 0; i < m_triData.Count; i++)
             {
                 GL.Begin(GL.TRIANGLES);
 
                 for (int j = 0; j < 3; j++)
                 {
                     GL.MultiTexCoord(0, m_triData[i].UV[j]);
                     GL.Vertex(m_triData[i].Vertices[j]);
                     //GL.MultiTexCoord(2, m_triData[i].BC[j]);
                 }
 
                 var c = m_triData[i].Center;
                 c.x *= screenratio;
                 m_triData[i].Matrix = Matrix4x4.Translate(m_triData[i].Dir * offset);
                 m_triData[i].Matrix = m_triData[i].Matrix * Matrix4x4.Translate(c);
                 m_triData[i].Matrix = m_triData[i].Matrix * Matrix4x4.Rotate(Quaternion.Euler(m_triData[i].Rotation * rotation));
                 m_triData[i].Matrix = m_triData[i].Matrix * Matrix4x4.Scale(new Vector3(0.97f, 0.97f, 0.97f));
                 m_triData[i].Matrix = m_triData[i].Matrix * Matrix4x4.Translate(-c);
 
                 GL.MultMatrix(m_triData[i].Matrix);
 
                 GL.End();
             }
 
             if (transformDelay < transitionTime)
             {
                 alpha -= 0.4f * Time.deltaTime;
                 offset += 0.1f * Time.deltaTime;
                 rotation += 0.4f * Time.deltaTime;
             }
             else
             {
                 transitionTime += Time.deltaTime;
             }
         }
 
         //GameManager.DisableLoadingScreen();
     }

I was trying to figure out how to achieve a screen shatter effect like THIS