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 Converts a `.ttf` font file into multichannel signed distance fields, then outputs packed spritesheets and a json representation of an AngelCode BMfont.
 
-Signed distance fields are a method of reproducing vector shapes from a texture representation, popularized in [this paper by Valve](http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf).
+Signed distance fields are a method of reproducing vector shapes from a texture representation, popularized in [this paper by Valve](https://steamcdn-a.akamaihd.net/apps/valve/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf).
 This tool uses [Chlumsky/msdfgen](https://github.com/Chlumsky/msdfgen) to generate multichannel signed distance fields to preserve corners. The distance fields are created from vector fonts, then rendered into texture pages. A BMFont object is provided for character layout.
 
 ## Install