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108 lines
3.4 KiB
Python
108 lines
3.4 KiB
Python
import math
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import struct
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MAX_5_BYTE_QUATERNION = 1 / (2 ** 0.5)
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SCALE_8_BYTE_QUATERNION_COMPRESS = 10000
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SCALE_8_BYTE_QUATERNION_DECOMPRESS = 1.0 / SCALE_8_BYTE_QUATERNION_COMPRESS
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SCALE_6_BYTE_VECTOR3_COMPRESS = 32000
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SCALE_6_BYTE_VECTOR3_DECOMPRESS = 1.0 / SCALE_6_BYTE_VECTOR3_COMPRESS
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def findBiggest(quat):
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biggest_i = -1
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biggest_v = 0
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for i, v in enumerate(quat):
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if abs(v) > biggest_v:
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biggest_v = abs(v)
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biggest_i = i
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if quat[biggest_i] < 0:
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return (biggest_i, (-quat[0], -quat[1], -quat[2], -quat[3]))
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else:
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return (biggest_i, ( quat[0], quat[1], quat[2], quat[3]))
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def compressQuaternion_5Byte(quat):
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#Find biggset value and negate the quaternion to make it positive.
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missing, q = findBiggest(quat)
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d = []
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for i in range(4):
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if i == missing:
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continue
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v = int(math.floor(0.5 + q[i] / MAX_5_BYTE_QUATERNION * 2048))
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if v < -2048:
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v = -2048
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elif v > 2047:
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v = 2047
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d.append(v + 2048)
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v = (
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(missing << 36) |
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(d[0] << 24) |
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(d[1] << 12) |
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d[2]
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)
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s = struct.pack("<Q", v)
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#Return with the top most byte first, but remaining bytes in little endian order.
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return s[4:5] + s[0:4]
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def decompressQuaternion_5Byte(data):
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#Source data has the top most byte first, but remaining bytes are little endian.
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#print("decompressQuaternion_5Byte(data): %s" % ([data],))
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#Rearrange byte data into a little endian uint64.
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s = data[1:5] + data[0:1] + b"\x00\x00\x00"
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(v, ) = struct.unpack("<Q", s)
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#Parse out the data.
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missing = (v >> 36) & 0x3
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d = [
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(v >> 24) & 0xfff,
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(v >> 12) & 0xfff,
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v & 0xfff,
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]
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#Rescale values and summing the squares into x.
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x = 0
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#print("%s" % (d, ))
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for i in range(3):
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d[i] = (d[i] - 2048) * MAX_5_BYTE_QUATERNION / 2048.0
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x += d[i] ** 2.0
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#print("%s -> %s" % (d, x))
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#Use pythagoras to compute the missing field into x.
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x = (1 - x) ** 0.5
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#Rebuild the quaternion.
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d_i = 0;
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q = []
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for i in range(4):
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if i == missing:
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q.append(x)
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else:
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q.append(d[d_i])
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d_i += 1
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return q
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def compressQuaternion_8Byte(quat):
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return struct.pack("<hhhh",
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int(math.floor(0.5 + quat[0] * SCALE_8_BYTE_QUATERNION_COMPRESS)),
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int(math.floor(0.5 + quat[1] * SCALE_8_BYTE_QUATERNION_COMPRESS)),
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int(math.floor(0.5 + quat[2] * SCALE_8_BYTE_QUATERNION_COMPRESS)),
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int(math.floor(0.5 + quat[3] * SCALE_8_BYTE_QUATERNION_COMPRESS))
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)
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def decompressQuaternion_8Byte(data):
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d = struct.unpack("<hhhh", data[0:8])
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return [
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d[0] * SCALE_8_BYTE_QUATERNION_DECOMPRESS,
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d[1] * SCALE_8_BYTE_QUATERNION_DECOMPRESS,
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d[2] * SCALE_8_BYTE_QUATERNION_DECOMPRESS,
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d[3] * SCALE_8_BYTE_QUATERNION_DECOMPRESS
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]
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def compressVector3_6Byte(vec):
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return struct.pack("<hhh",
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int(math.floor(0.5 + vec[0] * SCALE_6_BYTE_VECTOR3_COMPRESS)),
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int(math.floor(0.5 + vec[1] * SCALE_6_BYTE_VECTOR3_COMPRESS)),
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int(math.floor(0.5 + vec[2] * SCALE_6_BYTE_VECTOR3_COMPRESS))
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)
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def decompressVector3_6Byte(data):
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d = struct.unpack("<hhh", data[0:6])
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return [(x * SCALE_6_BYTE_VECTOR3_DECOMPRESS) for x in d]
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