1 /*
2 * Copyright (C) 2016 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 #include "common/math/quat.h"
18
clamp(float x)19 static float clamp(float x) { return x < 0.0f ? 0.0f : x; }
20
initQuat(Quat * q,const struct Mat33 * R)21 void initQuat(Quat *q, const struct Mat33 *R) {
22 float Hx = R->elem[0][0];
23 float My = R->elem[1][1];
24 float Az = R->elem[2][2];
25
26 q->x = sqrtf(clamp(Hx - My - Az + 1.0f) * 0.25f);
27 q->y = sqrtf(clamp(-Hx + My - Az + 1.0f) * 0.25f);
28 q->z = sqrtf(clamp(-Hx - My + Az + 1.0f) * 0.25f);
29 q->w = sqrtf(clamp(Hx + My + Az + 1.0f) * 0.25f);
30 q->x = copysignf(q->x, R->elem[1][2] - R->elem[2][1]);
31 q->y = copysignf(q->y, R->elem[2][0] - R->elem[0][2]);
32 q->z = copysignf(q->z, R->elem[0][1] - R->elem[1][0]);
33 }
34
quatToMatrix(struct Mat33 * R,const Quat * q)35 void quatToMatrix(struct Mat33 *R, const Quat *q) {
36 float q0 = q->w;
37 float q1 = q->x;
38 float q2 = q->y;
39 float q3 = q->z;
40 float sq_q1 = 2.0f * q1 * q1;
41 float sq_q2 = 2.0f * q2 * q2;
42 float sq_q3 = 2.0f * q3 * q3;
43 float q1_q2 = 2.0f * q1 * q2;
44 float q3_q0 = 2.0f * q3 * q0;
45 float q1_q3 = 2.0f * q1 * q3;
46 float q2_q0 = 2.0f * q2 * q0;
47 float q2_q3 = 2.0f * q2 * q3;
48 float q1_q0 = 2.0f * q1 * q0;
49
50 R->elem[0][0] = 1.0f - sq_q2 - sq_q3;
51 R->elem[1][0] = q1_q2 - q3_q0;
52 R->elem[2][0] = q1_q3 + q2_q0;
53 R->elem[0][1] = q1_q2 + q3_q0;
54 R->elem[1][1] = 1.0f - sq_q1 - sq_q3;
55 R->elem[2][1] = q2_q3 - q1_q0;
56 R->elem[0][2] = q1_q3 - q2_q0;
57 R->elem[1][2] = q2_q3 + q1_q0;
58 R->elem[2][2] = 1.0f - sq_q1 - sq_q2;
59 }
60
quatNormalize(Quat * q)61 void quatNormalize(Quat *q) {
62 if (q->w < 0.0f) {
63 q->x = -q->x;
64 q->y = -q->y;
65 q->z = -q->z;
66 q->w = -q->w;
67 }
68
69 float invNorm =
70 1.0f / sqrtf(q->x * q->x + q->y * q->y + q->z * q->z + q->w * q->w);
71
72 q->x *= invNorm;
73 q->y *= invNorm;
74 q->z *= invNorm;
75 q->w *= invNorm;
76 }
77