Useful GLSL functions - Random and Encode Float

helpful.glsl

float random(vec2 seed) { 
	return fract(cos(mod(123456780., 1024. * dot(seed / time, vec2(23.1406926327792690, 2.6651441426902251))))); 
}
float shift_right(float v, float amt) { 
	v = floor(v) + 0.5; return floor(v / exp2(amt)); 
}
float shift_left(float v, float amt) { 
	return floor(v * exp2(amt) + 0.5); 
}
float mask_last(float v, float bits) { 
	return mod(v, shift_left(1.0, bits)); 
}
float extract_bits(float num, float from, float to) { 
	from = floor(from + 0.5); to = floor(to + 0.5); 
	return mask_last(shift_right(num, from), to - from); 
}
vec4 encode_float(float val) { 
	if (val == 0.0) return vec4(0, 0, 0, 0); 
	float sign = val > 0.0 ? 0.0 : 1.0; 
	val = abs(val); 
	float exponent = floor(log2(val)); 
	float biased_exponent = exponent + 127.0; 
	float fraction = ((val / exp2(exponent)) - 1.0) * 8388608.0; 
	float t = biased_exponent / 2.0; 
	float last_bit_of_biased_exponent = fract(t) * 2.0; 
	float remaining_bits_of_biased_exponent = floor(t); 
	float byte4 = extract_bits(fraction, 0.0, 8.0) / 255.0; 
	float byte3 = extract_bits(fraction, 8.0, 16.0) / 255.0; 
	float byte2 = (last_bit_of_biased_exponent * 128.0 + extract_bits(fraction, 16.0, 23.0)) / 255.0; 
	float byte1 = (sign * 128.0 + remaining_bits_of_biased_exponent) / 255.0; 
	return vec4(byte4, byte3, byte2, byte1); 
}