OpenGL Insights

178 II Rendering Techniques

// Distance map 2D shape texturing , Stefan Gustavson 2011.

// A re-implementation of Green s method , using a single

// channel high precision distance map and explicit texel

// interpolation. This code is in the public domain .

#version 120

uniform sampler2D disttex ; // Single - channel distance field

uniform float texw , texh ; // Texture width and height ( texels )

varying float oneu , onev ; // 1/ texw and 1/ texh from vertex shader

varying vec2 st ; // Texture coords from vertex shader

void main (void )

{

vec2 uv = st * vec2 (texw , texh ); // Scale to texture rect coords

vec2 uv00 = floor (uv - vec2 (0.5) ); // Lower