132 lines
3.8 KiB
Plaintext
132 lines
3.8 KiB
Plaintext
/**
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* @file
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* @brief Functions related to 3D quaternions and Euler angles.
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* @author Krishna Vedala
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*/
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#include <stdio.h>
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#ifdef __arm__ // if compiling for ARM-Cortex processors
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#define LIBQUAT_ARM
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#include <arm_math.h>
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#else
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#include <math.h>
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#endif
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#include <assert.h>
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#include "geometry_datatypes.h"
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/**
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* @addtogroup quats 3D Quaternion operations
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* @{
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*/
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/**
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* Function to convert given Euler angles to a quaternion.
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* \f{eqnarray*}{
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* q_{0} & =
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* &\cos\left(\frac{\phi}{2}\right)\cos\left(\frac{\theta}{2}\right)\cos\left(\frac{\psi}{2}\right)
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* +
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* \sin\left(\frac{\phi}{2}\right)\sin\left(\frac{\theta}{2}\right)\sin\left(\frac{\psi}{2}\right)\\
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* q_{1} & =
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* &\sin\left(\frac{\phi}{2}\right)\cos\left(\frac{\theta}{2}\right)\cos\left(\frac{\psi}{2}\right)
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* -
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* \cos\left(\frac{\phi}{2}\right)\sin\left(\frac{\theta}{2}\right)\sin\left(\frac{\psi}{2}\right)\\
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* q_{2} & =
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* &\cos\left(\frac{\phi}{2}\right)\sin\left(\frac{\theta}{2}\right)\cos\left(\frac{\psi}{2}\right)
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* +
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* \sin\left(\frac{\phi}{2}\right)\cos\left(\frac{\theta}{2}\right)\sin\left(\frac{\psi}{2}\right)\\
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* q_{3} & =
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* &\cos\left(\frac{\phi}{2}\right)\cos\left(\frac{\theta}{2}\right)\sin\left(\frac{\psi}{2}\right)
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* -
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* \sin\left(\frac{\phi}{2}\right)\sin\left(\frac{\theta}{2}\right)\cos\left(\frac{\psi}{2}\right)\\
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* \f}
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*
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* @param [in] in_euler input Euler angles instance
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* @returns converted quaternion
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*/
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quaternion quat_from_euler(const euler *in_euler)
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{
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quaternion out_quat;
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if (!in_euler) // if null
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{
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fprintf(stderr, "%s: Invalid input.", __func__);
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return out_quat;
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}
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quaternion temp;
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float cy = cosf(in_euler->yaw * 0.5f);
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float sy = sinf(in_euler->yaw * 0.5f);
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float cp = cosf(in_euler->pitch * 0.5f);
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float sp = sinf(in_euler->pitch * 0.5f);
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float cr = cosf(in_euler->roll * 0.5f);
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float sr = sinf(in_euler->roll * 0.5f);
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temp.w = cr * cp * cy + sr * sp * sy;
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temp.q1 = sr * cp * cy - cr * sp * sy;
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temp.q2 = cr * sp * cy + sr * cp * sy;
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temp.q3 = cr * cp * sy - sr * sp * cy;
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return temp;
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}
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/**
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* Function to convert given quaternion to Euler angles.
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* \f{eqnarray*}{
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* \phi & = &
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* \tan^{-1}\left[\frac{2\left(q_0q_1+q_2q_3\right)}{1-2\left(q_1^2+q_2^2\right)}\right]\\
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* \theta & =
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* &-\sin^{-1}\left[2\left(q_0q_2-q_3q_1\right)\right]\\
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* \psi & = &
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* \tan^{-1}\left[\frac{2\left(q_0q_3+q_1q_2\right)}{1-2\left(q_2^2+q_3^2\right)}\right]\\
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* \f}
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*
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* @param [in] in_quat input quaternion instance
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* @returns converted euler angles
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*/
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euler euler_from_quat(const quaternion *in_quat)
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{
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euler out_euler;
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if (!in_quat) // if null
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{
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fprintf(stderr, "%s: Invalid input.", __func__);
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return out_euler;
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}
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out_euler.roll = atan2f(
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2.f * (in_quat->w * in_quat->q1 + in_quat->q2 * in_quat->q3),
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1.f - 2.f * (in_quat->q1 * in_quat->q1 + in_quat->q2 * in_quat->q2));
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out_euler.pitch =
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asinf(2.f * (in_quat->w * in_quat->q2 + in_quat->q1 * in_quat->q3));
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out_euler.yaw = atan2f(
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2.f * (in_quat->w * in_quat->q3 + in_quat->q1 * in_quat->q2),
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1.f - 2.f * (in_quat->q2 * in_quat->q2 + in_quat->q3 * in_quat->q3));
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return out_euler;
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}
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/** @} */
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static void test()
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{
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quaternion quat = {0.7071f, 0.7071f, 0.f, 0.f};
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euler eul = euler_from_quat(&quat);
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printf("Euler: %.4g, %.4g, %.4g\n", eul.pitch, eul.roll, eul.yaw);
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quaternion test_quat = quat_from_euler(&eul);
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printf("Quaternion: %.4g %+.4g %+.4g %+.4g\n", test_quat.w,
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test_quat.dual.x, test_quat.dual.y, test_quat.dual.z);
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assert(fabsf(test_quat.w - quat.w) < .01);
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assert(fabsf(test_quat.q1 - quat.q1) < .01);
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assert(fabsf(test_quat.q2 - quat.q2) < .01);
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assert(fabsf(test_quat.q3 - quat.q3) < .01);
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}
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int main()
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{
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test();
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return 0;
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}
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