1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_QUAT_H
18#define ANDROID_QUAT_H
19
20#include <math.h>
21
22#include "vec.h"
23#include "mat.h"
24
25// -----------------------------------------------------------------------
26namespace android {
27// -----------------------------------------------------------------------
28
29template <typename TYPE>
30mat<TYPE, 3, 3> quatToMatrix(const vec<TYPE, 4>& q) {
31    mat<TYPE, 3, 3> R;
32    TYPE q0(q.w);
33    TYPE q1(q.x);
34    TYPE q2(q.y);
35    TYPE q3(q.z);
36    TYPE sq_q1 = 2 * q1 * q1;
37    TYPE sq_q2 = 2 * q2 * q2;
38    TYPE sq_q3 = 2 * q3 * q3;
39    TYPE q1_q2 = 2 * q1 * q2;
40    TYPE q3_q0 = 2 * q3 * q0;
41    TYPE q1_q3 = 2 * q1 * q3;
42    TYPE q2_q0 = 2 * q2 * q0;
43    TYPE q2_q3 = 2 * q2 * q3;
44    TYPE q1_q0 = 2 * q1 * q0;
45    R[0][0] = 1 - sq_q2 - sq_q3;
46    R[0][1] = q1_q2 - q3_q0;
47    R[0][2] = q1_q3 + q2_q0;
48    R[1][0] = q1_q2 + q3_q0;
49    R[1][1] = 1 - sq_q1 - sq_q3;
50    R[1][2] = q2_q3 - q1_q0;
51    R[2][0] = q1_q3 - q2_q0;
52    R[2][1] = q2_q3 + q1_q0;
53    R[2][2] = 1 - sq_q1 - sq_q2;
54    return R;
55}
56
57template <typename TYPE>
58vec<TYPE, 4> matrixToQuat(const mat<TYPE, 3, 3>& R) {
59    // matrix to quaternion
60
61    struct {
62        inline TYPE operator()(TYPE v) {
63            return v < 0 ? 0 : v;
64        }
65    } clamp;
66
67    vec<TYPE, 4> q;
68    const float Hx = R[0].x;
69    const float My = R[1].y;
70    const float Az = R[2].z;
71    q.x = sqrtf( clamp( Hx - My - Az + 1) * 0.25f );
72    q.y = sqrtf( clamp(-Hx + My - Az + 1) * 0.25f );
73    q.z = sqrtf( clamp(-Hx - My + Az + 1) * 0.25f );
74    q.w = sqrtf( clamp( Hx + My + Az + 1) * 0.25f );
75    q.x = copysignf(q.x, R[2].y - R[1].z);
76    q.y = copysignf(q.y, R[0].z - R[2].x);
77    q.z = copysignf(q.z, R[1].x - R[0].y);
78    // guaranteed to be unit-quaternion
79    return q;
80}
81
82template <typename TYPE>
83vec<TYPE, 4> normalize_quat(const vec<TYPE, 4>& q) {
84    vec<TYPE, 4> r(q);
85    if (r.w < 0) {
86        r = -r;
87    }
88    return normalize(r);
89}
90
91// -----------------------------------------------------------------------
92
93typedef vec4_t quat_t;
94
95// -----------------------------------------------------------------------
96}; // namespace android
97
98#endif /* ANDROID_QUAT_H */
99