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Unity Surface Shader Cartoon Renderer

September 6, 2015

In the newer versions of Unity, shaders use a Surface function, as opposed to a Vert/Frag combo to render everything.  But they also allow for a vertex function to be used if it’s needed.  The problem I was finding is, in the lower level vert/frag shader format the vertex function is in view space, whereas the vertex shader in a surface shader is in model space.  This makes it difficult to do things such as moving vertices along the XY plane while keeping the Z plane static.

It took me a little while, but I eventually managed to cobble together a function that achieves the cartoon look that I was looking for.  I still don’t quite understand why the normal has to be flipped, but it appears to work.  If anyone knows why I had to flip the normal, please let me know.

        void vert (inout appdata_full v) 
        {
             float4 eyePosition =  mul (UNITY_MATRIX_MV, v.vertex);
            float4x4 it_mv = UNITY_MATRIX_IT_MV;
            float3 norm   = normalize(mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal));
            float2 offset = -norm.xy;
            eyePosition.xy += offset * eyePosition.z * _Outline;
            v.vertex = mul(eyePosition, it_mv);
        }
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From → C#, Programming, Shaders

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