A signed distance field texture is a technique where you store the distance from a pixel to the surface of a shape within the color information for that pixel, allowing almost vector graphics quality rendering using textures (http://blog.demofox.org/2014/06/30/distance-field-textures/)

When reading the texture data in a shader, you get values between 0 and 1, which is meant to map between -1 and 1.

The distance data is essentially "normalized" when creating the shader, which means that instead of storing a true positive or negative distance value in the texture, you instead multiply (divide) the real distance by some constant value, clamp it to be between 0 and 1 and then store that distance value.

That constant value essentially controls the width in pixels of the "gradient" band, where the surface of the shape goes from 0 to 1 (-1 to 1).

Is there an optimal value for this based on the output texture resolution or anything else? I always use trial and error until it looks right but feel there must be a better way.

Also, is there a way to choose an optimal output texture size? Or should you just always use a texture size smaller than the size you intend to render it at?


  • $\begingroup$ Very interesting post. Could you post some images using different constants? $\endgroup$ – Andreas Apr 18 '16 at 18:07
  • $\begingroup$ Perhaps I'm misunderstanding some part of this. Wouldn't you want to find the maximum absolute distance in your texture and use that as the constant? $\endgroup$ – user1118321 Mar 19 '18 at 2:18

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