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// Jump flooding algorithm for EDT according
// to Danielsson (1980) and Guodong Rong (2007).
// Implementation by Stefan Gustavson 2010.
// This code is in the public domain.
// This shader initializes the distance field
// in preparation for the flood filling.
uniform sampler2D texture;
varying float stepu;
varying float stepv;
varying vec2 uv;
void main( void )
{
float pixel = texture2D(texture, uv).r;
vec4 myzero = vec4(128. / 255., 128. / 255., 0., 0.); // Zero
vec4 myinfinity = vec4(0., 0., 0., 0.); // Infinity
// Pixels > 0.5 are objects, others are background
gl_FragColor = pixel > 0.5 ? myinfinity : myzero;
}
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