OpenVDB 5.1.0

QuantizedUnitVec.h
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1 //
3 // Copyright (c) 2012-2018 DreamWorks Animation LLC
4 //
5 // All rights reserved. This software is distributed under the
6 // Mozilla Public License 2.0 ( http://www.mozilla.org/MPL/2.0/ )
7 //
8 // Redistributions of source code must retain the above copyright
9 // and license notice and the following restrictions and disclaimer.
10 //
11 // * Neither the name of DreamWorks Animation nor the names of
12 // its contributors may be used to endorse or promote products derived
13 // from this software without specific prior written permission.
14 //
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28 //
30
31 #ifndef OPENVDB_MATH_QUANTIZED_UNIT_VEC_HAS_BEEN_INCLUDED
32 #define OPENVDB_MATH_QUANTIZED_UNIT_VEC_HAS_BEEN_INCLUDED
33
34 #include <openvdb/Platform.h>
35 #include <openvdb/version.h>
36 #include "Vec3.h"
37
38 namespace openvdb {
39 OPENVDB_USE_VERSION_NAMESPACE
40 namespace OPENVDB_VERSION_NAME {
41 namespace math {
42
46 class OPENVDB_API QuantizedUnitVec
47 {
48 public:
49 template<typename T> static uint16_t pack(const Vec3<T>& vec);
50 static Vec3s unpack(const uint16_t data);
51
52 static void flipSignBits(uint16_t&);
53
54 private:
55 QuantizedUnitVec() {}
56
57 // bit masks
58 static const uint16_t MASK_SLOTS = 0x1FFF; // 0001111111111111
59 static const uint16_t MASK_XSLOT = 0x1F80; // 0001111110000000
60 static const uint16_t MASK_YSLOT = 0x007F; // 0000000001111111
61 static const uint16_t MASK_XSIGN = 0x8000; // 1000000000000000
62 static const uint16_t MASK_YSIGN = 0x4000; // 0100000000000000
63 static const uint16_t MASK_ZSIGN = 0x2000; // 0010000000000000
64
65 // normalization weights, 32 kilobytes.
66 static float sNormalizationWeights[MASK_SLOTS + 1];
67 }; // class QuantizedUnitVec
68
69
71
72
73 template<typename T>
74 inline uint16_t
75 QuantizedUnitVec::pack(const Vec3<T>& vec)
76 {
77 if (math::isZero(vec)) return 0;
78
79 uint16_t data = 0;
80 T x(vec[0]), y(vec[1]), z(vec[2]);
81
82 // The sign of the three components are first stored using
83 // 3-bits and can then safely be discarded.
84 if (x < T(0.0)) { data |= MASK_XSIGN; x = -x; }
85 if (y < T(0.0)) { data |= MASK_YSIGN; y = -y; }
86 if (z < T(0.0)) { data |= MASK_ZSIGN; z = -z; }
87
88 // The z component is discarded and x & y are quantized in
89 // the 0 to 126 range.
90 T w = T(126.0) / (x + y + z);
91 uint16_t xbits = static_cast<uint16_t>((x * w));
92 uint16_t ybits = static_cast<uint16_t>((y * w));
93
94 // The remaining 13 bits in our 16 bit word are dividied into a
95 // 6-bit x-slot and a 7-bit y-slot. Both the xbits and the ybits
96 // can still be represented using (2^7 - 1) quantization levels.
97
98 // If the xbits requre more than 6-bits, store the complement.
99 // (xbits + ybits < 127, thus if xbits > 63 => ybits <= 63)
100 if (xbits > 63) {
101 xbits = static_cast<uint16_t>(127 - xbits);
102 ybits = static_cast<uint16_t>(127 - ybits);
103 }
104
105 // Pack components into their respective slots.
106 data = static_cast<uint16_t>(data | (xbits << 7));
107 data = static_cast<uint16_t>(data | ybits);
108 return data;
109 }
110
111
112 inline Vec3s
113 QuantizedUnitVec::unpack(const uint16_t data)
114 {
115 const float w = sNormalizationWeights[data & MASK_SLOTS];
116
117 uint16_t xbits = static_cast<uint16_t>((data & MASK_XSLOT) >> 7);
118 uint16_t ybits = static_cast<uint16_t>(data & MASK_YSLOT);
119
120 // Check if the complement components where stored and revert.
121 if ((xbits + ybits) > 126) {
122 xbits = static_cast<uint16_t>(127 - xbits);
123 ybits = static_cast<uint16_t>(127 - ybits);
124 }
125
126 Vec3s vec(float(xbits) * w, float(ybits) * w, float(126 - xbits - ybits) * w);
127
128 if (data & MASK_XSIGN) vec[0] = -vec[0];
129 if (data & MASK_YSIGN) vec[1] = -vec[1];
130 if (data & MASK_ZSIGN) vec[2] = -vec[2];
131 return vec;
132 }
133
134
136
137
138 inline void
139 QuantizedUnitVec::flipSignBits(uint16_t& v)
140 {
141 v = static_cast<uint16_t>((v & MASK_SLOTS) | (~v & ~MASK_SLOTS));
142 }
143
144 } // namespace math
145 } // namespace OPENVDB_VERSION_NAME
146 } // namespace openvdb
147
148 #endif // OPENVDB_MATH_QUANTIZED_UNIT_VEC_HAS_BEEN_INCLUDED
149
150 // Copyright (c) 2012-2018 DreamWorks Animation LLC
151 // All rights reserved. This software is distributed under the
152 // Mozilla Public License 2.0 ( http://www.mozilla.org/MPL/2.0/ )
OPENVDB_API
#define OPENVDB_API
Helper macros for defining library symbol visibility.
Definition: Platform.h:194
Vec3.h
openvdb::v5_1::math::isZero
bool isZero(const Type &x)
Return true if x is exactly equal to zero.
Definition: Math.h:308
openvdb::v5_1::math::Vec3
Definition: Mat.h:197
OPENVDB_VERSION_NAME
#define OPENVDB_VERSION_NAME
The version namespace name for this library version.
Definition: version.h:136
openvdb::v5_1::math::QuantizedUnitVec
Unit vector occupying only 16 bits.
Definition: QuantizedUnitVec.h:46
openvdb
Definition: Exceptions.h:40
version.h
Library and file format version numbers.
OPENVDB_USE_VERSION_NAMESPACE
#define OPENVDB_USE_VERSION_NAMESPACE
Definition: version.h:188
Platform.h