1 files changed, 96 insertions, 0 deletions
diff --git a/compat/euler.cpp b/compat/euler.cpp
new file mode 100644
index 00000000..a1034bc9
--- /dev/null
+++ b/compat/euler.cpp
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+#include "euler.hpp"
+#include <cmath>
+
+namespace euler {
+
+euler_t OPENTRACK_COMPAT_EXPORT rmat_to_euler(const rmat& R)
+{
+    using std::atan2;
+    using std::sqrt;
+
+    const double cy = sqrt(R(2,2)*R(2, 2) + R(2, 1)*R(2, 1));
+    const bool large_enough = cy > 1e-10;
+    if (large_enough)
+        return euler_t(atan2(-R(1, 0), R(0, 0)),
+                       atan2(R(2, 0), cy),
+                       atan2(-R(2, 1), R(2, 2)));
+    else
+        return euler_t(atan2(R(0, 1), R(1, 1)),
+                       atan2(R(2, 0), cy),
+                       0);
+}
+
+// tait-bryan angles, not euler
+rmat OPENTRACK_COMPAT_EXPORT euler_to_rmat(const euler_t& input)
+{
+    const double H = -input(0);
+    const double P = -input(1);
+    const double B = -input(2);
+
+    using std::cos;
+    using std::sin;
+
+    const auto c1 = cos(H);
+    const auto s1 = sin(H);
+    const auto c2 = cos(P);
+    const auto s2 = sin(P);
+    const auto c3 = cos(B);
+    const auto s3 = sin(B);
+
+    return rmat(
+                // z
+                c1 * c2,
+                c1 * s2 * s3 - c3 * s1,
+                s1 * s3 + c1 * c3 * s2,
+                // y
+                c2 * s1,
+                c1 * c3 + s1 * s2 * s3,
+                c3 * s1 * s2 - c1 * s3,
+                // x
+                -s2,
+                c2 * s3,
+                c2 * c3
+                );
+}
+
+// https://en.wikipedia.org/wiki/Davenport_chained_rotations#Tait.E2.80.93Bryan_chained_rotations
+void OPENTRACK_COMPAT_EXPORT tait_bryan_to_matrices(const euler_t& input,
+                                                    rmat& r_roll,
+                                                    rmat& r_pitch,
+                                                    rmat& r_yaw)
+{
+    using std::cos;
+    using std::sin;
+
+    {
+        const double phi = -input(2);
+        const double sin_phi = sin(phi);
+        const double cos_phi = cos(phi);
+
+        r_roll = rmat(1, 0, 0,
+                      0, cos_phi, -sin_phi,
+                      0, sin_phi, cos_phi);
+    }
+
+    {
+        const double theta = input(1);
+        const double sin_theta = sin(theta);
+        const double cos_theta = cos(theta);
+
+        r_pitch = rmat(cos_theta, 0, -sin_theta,
+                       0, 1, 0,
+                       sin_theta, 0, cos_theta);
+    }
+
+    {
+        const double psi = -input(0);
+        const double sin_psi = sin(psi);
+        const double cos_psi = cos(psi);
+
+        r_yaw = rmat(cos_psi, -sin_psi, 0,
+                     sin_psi, cos_psi, 0,
+                     0, 0, 1);
+    }
+}
+
+} // end ns euler