packing a float into a A8R8G8B8 texture (shader)

encode (fDist is the normalized distance):

	const float4 bitSh	= float4(   256*256*256, 256*256,   256,         1);
	const float4 bitMsk = float4(   0,      1.0/256.0,    1.0/256.0,    1.0/256.0);

	float4 comp;
	comp	= fDist * bitSh;
	comp	= frac(comp);
	comp	-= comp.xxyz * bitMsk;
	return comp;

decode (vec is the rgba encoded value):

	const float4 bitShifts = float4(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0, 1);
	return dot(vec.xyzw , bitShifts);