Repeat texture in mirror mode

Question

Is it possible to set your uv tiling on mirror repeat? I do know that OpenGL supports it and DirectX does so too.

So, instead of just repeating the texture, the texture needs to be flipped instead of just repeated.

http://www.opengl.org/registry/specs/ARB/texture\_mirrored\_repeat.txt

mirror repeated texture

Answer 1

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Answer by Mortennobel · Sep 17, 2011 at 02:19 PM

No it is not possible to change the UV to mirror mode. However if your UVs is set to repeat, you can easily achieve the same effect by writing a custom shader.

I have implemented a simple diffuse shader that does the trick:

 Shader "Custom/DiffuseUVMirrowShader" {
 Properties {
     _Color ("Main Color", Color) = (1,1,1,1)
     _MainTex ("Base (RGB)", 2D) = "white" {}
 }
 SubShader {
     Tags { "RenderType"="Opaque" }
     LOD 200
 
 CGPROGRAM
 #pragma surface surf Lambert
 
 sampler2D _MainTex;
 float4 _Color;
 
 struct Input {
     float2 uv_MainTex;
 };
 
 void surf (Input IN, inout SurfaceOutput o) {
     float2 t = frac(IN.uv_MainTex*0.5)*2.0;
     float2 length = {1.0,1.0};
     float2 mirrorTexCoords = length-abs(t-length);
     half4 c = tex2D(_MainTex,  mirrorTexCoords) * _Color;
     o.Albedo = c.rgb;
     o.Alpha = c.a;
 }
 ENDCG
 }
 
 Fallback "VertexLit"
 }

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Marnix · Sep 17, 2011 at 02:53 PM 0

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Ok thanks for the confirmation and the shader example. That was my second option, but I don't like writing shaders for every different kind of change I want to make. Because I would need to write shaders for every kind of lighting that needs this functionality. So: Diffuse, Specular, Transparent of all... It wouldn't make it better. I think I can better change my texture to make it seamless. That will be an easier solution.

Mortennobel · Sep 17, 2011 at 07:27 PM 0

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I you change your $$anonymous$$d and want to play with shaders: I have written a blog post about how I changed the diffuse shader to use UV mirroring: http://blog.nobel-joergensen.com/2011/09/17/mirror-texture-coordinates-in-unity/

jnt · Jan 21, 2015 at 04:44 PM 0

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Thanks so much for this shader code! I can now halve my texture size for symmetrical objects in my mobile game - every bit of optimization counts ;)

Answer 2

Answer by xxxMaJaxxx · Mar 01, 2021 at 07:32 PM

https://docs.unity3d.com/Manual/SL-SamplerStates.html

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Repeat texture in mirror mode

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