Hello,

I wrote a MatCap shader following this idea:

Given the image representing the texture, we compute the sample point by taking the dot product of the vertex normal and the camera position and remapping this to [0,1].

This seems to work well when I look straight at an object with this shader. However, in cases where the camera points slightly on the side, I can see the texture stretch a lot.

Could anyone give me a hint as how to get a nice matcap shader ?

Here's what I wrote:

Shader "Unlit/Matcap"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
            };

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

            sampler2D _MainTex;            

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.worldNormal = mul((float3x3)UNITY_MATRIX_V, UnityObjectToWorldNormal(v.normal)).xy*0.3 + 0.5;  //UnityObjectToClipPos(v.normal)*0.5 + 0.5;
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.worldNormal);
                // apply fog
                return col;
            }
            ENDCG
        }
    }
}

Thanks!