mirror of https://github.com/ArduPilot/ardupilot
72 lines
1.7 KiB
C++
72 lines
1.7 KiB
C++
#include "AP_Math.h"
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// a varient of asin() that checks the input ranges and ensures a
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// valid angle as output. If nan is given as input then zero is
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// returned.
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float safe_asin(float v)
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{
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if (isnan(v)) {
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return 0.0;
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}
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if (v >= 1.0) {
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return PI/2;
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}
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if (v <= -1.0) {
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return -PI/2;
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}
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return asin(v);
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}
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// a varient of sqrt() that checks the input ranges and ensures a
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// valid value as output. If a negative number is given then 0 is
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// returned. The reasoning is that a negative number for sqrt() in our
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// code is usually caused by small numerical rounding errors, so the
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// real input should have been zero
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float safe_sqrt(float v)
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{
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float ret = sqrt(v);
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if (isnan(ret)) {
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return 0;
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}
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return ret;
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}
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// create a rotation matrix given some euler angles
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// this is based on http://gentlenav.googlecode.com/files/EulerAngles.pdf
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void rotation_matrix_from_euler(Matrix3f &m, float roll, float pitch, float yaw)
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{
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float cp = cos(pitch);
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float sp = sin(pitch);
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float sr = sin(roll);
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float cr = cos(roll);
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float sy = sin(yaw);
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float cy = cos(yaw);
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m.a.x = cp * cy;
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m.a.y = (sr * sp * cy) - (cr * sy);
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m.a.z = (cr * sp * cy) + (sr * sy);
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m.b.x = cp * sy;
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m.b.y = (sr * sp * sy) + (cr * cy);
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m.b.z = (cr * sp * sy) - (sr * cy);
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m.c.x = -sp;
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m.c.y = sr * cp;
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m.c.z = cr * cp;
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}
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// calculate euler angles from a rotation matrix
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// this is based on http://gentlenav.googlecode.com/files/EulerAngles.pdf
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void calculate_euler_angles(const Matrix3f &m, float *roll, float *pitch, float *yaw)
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{
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if (pitch != NULL) {
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*pitch = -safe_asin(m.c.x);
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}
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if (roll != NULL) {
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*roll = atan2(m.c.y, m.c.z);
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}
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if (yaw != NULL) {
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*yaw = atan2(m.b.x, m.a.x);
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}
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}
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