RSDK-3865 - implement get_components for orientation vector in spatia…

…lmath FFI (#58)

src/ffi/spatialmath/orientation_vector.rs

@@ -1,18 +1,19 @@
 use ffi_helpers::null_pointer_check;
+use libc::c_double;
 use nalgebra::Quaternion;
 
 use crate::spatialmath::utils::OrientationVector;
 
 /// The FFI Interface for initialization of Viam's Orientation Vector format.
 /// Like an axis angle, the format involves a vector axis and a rotation
-/// theta (in radians). However, unlike an axis-angle, an orientation vector alters 
-/// the axes of the given frame of reference by rotating the z-axis to the 
-/// vector axis provided. The new x-axis is the vector that is both orthogonal to 
+/// theta (in radians). However, unlike an axis-angle, an orientation vector alters
+/// the axes of the given frame of reference by rotating the z-axis to the
+/// vector axis provided. The new x-axis is the vector that is both orthogonal to
 /// the vector axis provided and co-planar with both the old
-/// z-axis and the vector axis (this leaves two choices for the y-axis, 
-/// but the canonical "right-hand rule" is used to select one consistently). Then, 
+/// z-axis and the vector axis (this leaves two choices for the y-axis,
+/// but the canonical "right-hand rule" is used to select one consistently). Then,
 /// a clockwise-rotation of theta is applied about the new-z axis
-/// 
+///
 /// It is highly recommended not to attempt any mathematics with the orientation
 /// vector directly and to convert to quaternions via the FFI interface instead
 
@@ -23,9 +24,9 @@ fn to_raw_pointer(o_vec: &OrientationVector) -> *mut OrientationVector {
 }
 
 /// Free memory at the address of the orientation vector pointer. Outer processes
-/// that work with OrientationVectors via the FFI interface MUST remember 
+/// that work with OrientationVectors via the FFI interface MUST remember
 /// to call this function when finished with a OrientationVector instance
-/// 
+///
 /// # Safety
 #[no_mangle]
 pub unsafe extern "C" fn free_orientation_vector_memory(ptr: *mut OrientationVector) {
@@ -35,34 +36,58 @@ pub unsafe extern "C" fn free_orientation_vector_memory(ptr: *mut OrientationVec
     let _ = Box::from_raw(ptr);
 }
 
-
 /// Initialize an orientation vector from raw components and retrieve the C pointer
 /// to its address.
-/// 
+///
 /// # Safety
-/// 
+///
 /// When finished with the underlying orientation vector initialized by this function
-/// the caller must remember to free the orientation vector memory using the 
+/// the caller must remember to free the orientation vector memory using the
 /// free_orientation_vector_memory FFI function
 #[no_mangle]
 pub unsafe extern "C" fn new_orientation_vector(
-    o_x: f64, o_y: f64, o_z: f64, theta: f64
+    o_x: f64,
+    o_y: f64,
+    o_z: f64,
+    theta: f64,
 ) -> *mut OrientationVector {
     let o_vec = OrientationVector::new(o_x, o_y, o_z, theta);
     to_raw_pointer(&o_vec)
 }
 
+/// Get the components of an orientation vector as a list of C doubles, the order of the
+/// components will be (o_x, o_y, o_z, theta).
+///
+/// # Safety
+///
+/// When finished with the underlying orientation_vector passed to this function
+/// the caller must remember to free the orientation_vector memory using the
+/// free_orientation_vector_memory FFI function
+#[no_mangle]
+pub unsafe extern "C" fn orientation_vector_get_components(
+    ov_ptr: *const OrientationVector,
+) -> *const c_double {
+    null_pointer_check!(ov_ptr);
+    let components: [c_double; 4] = [
+        (*ov_ptr).o_vector.x,
+        (*ov_ptr).o_vector.y,
+        (*ov_ptr).o_vector.z,
+        (*ov_ptr).theta,
+    ];
+    Box::into_raw(Box::new(components)) as *const _
+}
+
 /// Converts a quaternion into an orientation vector.
-/// 
+///
 /// # Safety
-/// 
+///
 /// When finished with the underlying quaternion passed to this function
-/// the caller must remember to free the quaternion memory using the 
+/// the caller must remember to free the quaternion memory using the
 /// free_quaternion_memory FFI function and the orientation-vector memory using
 /// the free_orientation_vector_memory function
 #[no_mangle]
 pub unsafe extern "C" fn orientation_vector_from_quaternion(
-    quat_ptr: *const Quaternion<f64>
+    quat_ptr: *const Quaternion<f64>,
 ) -> *mut OrientationVector {
     null_pointer_check!(quat_ptr);
     let o_vec: OrientationVector = (*quat_ptr).into();