[ft-devel] Signed distance fields: distance from any point to the glyph contours

[Nicolas Rougier]

Hi,

One technics for rendering scalable text in OpenGL is the use of signed 
distance fields (signed distance to the glyph outlines) that are stored in a 
texture. Results are not perfect but acceptable in most cases. The way to 
compute such distance fields in freetype-gl 
(http://code.google.com/p/freetype-gl/) is to generate the bitmap of the glyph 
at high resolution, compute the (approximated) distance field on these bitmap 
and then downscale it. Of course, we lost a lot of precision (and time) in the 
operation.

My question relates to a more direct way to compute the signed distance and to 
know if anyone has already coded it by any chance ? Said differently, is there 
a quick way to compute the shortest signed distance from any point (x,y) to the 
glyph contours ?


Nicolas