move rmat->euler and euler->rmat conversions to header

1 files changed, 57 insertions, 1 deletions

diff --git a/opentrack/simple-mat.hpp b/opentrack/simple-mat.hpp
index b36b21ba..447327a8 100644
--- a/opentrack/simple-mat.hpp
+++ b/opentrack/simple-mat.hpp
@@ -75,7 +75,63 @@ struct Mat
 
         return ret;
     }
+    
+    template<int h_, int w_> using dmat = Mat<double, h_, w_>;
+    
+    // http://stackoverflow.com/a/18436193
+    static dmat<3, 1> rmat_to_euler(const dmat<3, 3>& R)
+    {
+        static constexpr double pi = 3.141592653;
+        const double up = 90 * pi / 180.;
+        static constexpr double bound = 1. - 2e-4;
+        if (R(0, 2) > bound)
+        {
+            double roll = atan(R(1, 0) / R(2, 0));
+            return dmat<3, 1>({0., up, roll});
+        }
+        if (R(0, 2) < -bound)
+        {
+            double roll = atan(R(1, 0) / R(2, 0));
+            return dmat<3, 1>({0., -up, roll});
+        }
+        double pitch = asin(-R(0, 2));
+        double roll = atan2(R(1, 2), R(2, 2));
+        double yaw = atan2(R(0, 1), R(0, 0));
+        return dmat<3, 1>({yaw, pitch, roll});
+    }
+    
+    // tait-bryan angles, not euler
+    static dmat<3, 3> euler_to_rmat(const double* input)
+    {
+        static constexpr double pi = 3.141592653;
+        auto H = input[0] * pi / 180;
+        auto P = input[1] * pi / 180;
+        auto B = input[2] * pi / 180;
+    
+        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);
+    
+        double foo[] = {
+            // 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
+        };
+    
+        return dmat<3, 3>(foo);
+    }
 };
 
 template<int h, int w> using dmat = Mat<double, h, w>;
-