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1 // Copyright 2017 The Chromium Authors. All rights reserved. | 1 // Copyright 2017 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "ui/gfx/geometry/quaternion.h" | 5 #include "ui/gfx/geometry/quaternion.h" |
6 | 6 |
7 #include <algorithm> | 7 #include <algorithm> |
8 #include <cmath> | 8 #include <cmath> |
9 | 9 |
10 #include "base/strings/stringprintf.h" | 10 #include "base/strings/stringprintf.h" |
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59 Quaternion Quaternion::Slerp(const Quaternion& q, double t) const { | 59 Quaternion Quaternion::Slerp(const Quaternion& q, double t) const { |
60 double dot = x_ * q.x_ + y_ * q.y_ + z_ * q.z_ + w_ * q.w_; | 60 double dot = x_ * q.x_ + y_ * q.y_ + z_ * q.z_ + w_ * q.w_; |
61 | 61 |
62 // Clamp dot to -1.0 <= dot <= 1.0. | 62 // Clamp dot to -1.0 <= dot <= 1.0. |
63 dot = std::min(std::max(dot, -1.0), 1.0); | 63 dot = std::min(std::max(dot, -1.0), 1.0); |
64 | 64 |
65 // Quaternions are facing the same direction. | 65 // Quaternions are facing the same direction. |
66 if (std::abs(dot - 1.0) < kEpsilon || std::abs(dot + 1.0) < kEpsilon) | 66 if (std::abs(dot - 1.0) < kEpsilon || std::abs(dot + 1.0) < kEpsilon) |
67 return *this; | 67 return *this; |
68 | 68 |
69 // TODO(vmpstr): In case the dot is 0, the vectors are exactly opposite | |
70 // of each other. In this case, it's technically not correct to just pick one | |
71 // of the vectors, we instead need to pick how to interpolate. However, the | |
72 // spec isn't clear on this. If we don't handle the -1 case explicitly, it | |
73 // results in inf and nans however, which is worse. See crbug.com/506543 for | |
74 // more discussion. | |
75 if (std::abs(dot) < kEpsilon) | |
76 return *this; | |
77 | |
78 double denom = std::sqrt(1.0 - dot * dot); | 69 double denom = std::sqrt(1.0 - dot * dot); |
79 double theta = std::acos(dot); | 70 double theta = std::acos(dot); |
80 double w = std::sin(t * theta) * (1.0 / denom); | 71 double w = std::sin(t * theta) * (1.0 / denom); |
81 | 72 |
82 double s1 = std::cos(t * theta) - dot * w; | 73 double s1 = std::cos(t * theta) - dot * w; |
83 double s2 = w; | 74 double s2 = w; |
84 | 75 |
85 return (s1 * *this) + (s2 * q); | 76 return (s1 * *this) + (s2 * q); |
86 } | 77 } |
87 | 78 |
88 Quaternion Quaternion::Lerp(const Quaternion& q, double t) const { | 79 Quaternion Quaternion::Lerp(const Quaternion& q, double t) const { |
89 return (((1.0 - t) * *this) + (t * q)).Normalized(); | 80 return (((1.0 - t) * *this) + (t * q)).Normalized(); |
90 } | 81 } |
91 | 82 |
92 Quaternion Quaternion::Normalized() const { | 83 Quaternion Quaternion::Normalized() const { |
93 double length = x_ * x_ + y_ * y_ + z_ * z_ + w_ * w_; | 84 double length = x_ * x_ + y_ * y_ + z_ * z_ + w_ * w_; |
94 if (length < kEpsilon) | 85 if (length < kEpsilon) |
95 return *this; | 86 return *this; |
96 return *this / sqrt(length); | 87 return *this / sqrt(length); |
97 } | 88 } |
98 | 89 |
99 std::string Quaternion::ToString() const { | 90 std::string Quaternion::ToString() const { |
100 return base::StringPrintf("[%f %f %f %f]", x_, y_, z_, w_); | 91 return base::StringPrintf("[%f %f %f %f]", x_, y_, z_, w_); |
101 } | 92 } |
102 | 93 |
103 } // namespace gfx | 94 } // namespace gfx |
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