packdepth.inc.glsl

vec4 packDepth(const in float depth) {
	const vec4 bit_shift = vec4( 256.0*256.0*256.0, 256.0*256.0,  256.0, 1.0);
	const vec4 bit_mask  = vec4( 0.0, 1.0/256.0, 1.0/256.0, 1.0/256.0);
	vec4 res = fract(depth * bit_shift);
	res -= res.xxyz * bit_mask;
	return res;  		
}

float unpackDepth(const in vec4 rgba_depth) {
	const vec4 bit_shift = vec4(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0, 1.0);
	float depth = dot(rgba_depth, bit_shift);
	return depth;
}  

packdepth2.inc.glsl

vec4 packDepth(float v ) {
  vec4 enc = vec4(1.0, 255.0, 65025.0, 160581375.0) * v;
  enc = fract(enc);
  enc -= enc.yzww * vec4(1.0/255.0,1.0/255.0,1.0/255.0,0.0);
  return enc;
}
 
float unpackDepth(vec4 rgba ) {
  return dot( rgba, vec4(1.0, 1/255.0, 1/65025.0, 1/160581375.0) );
}