Make camera setting more robust

Co-authored-by: Diego Ferigo <[email protected]>

src/jaxsim/mujoco/loaders.py

@@ -1,3 +1,4 @@
+import dataclasses
 import pathlib
 import tempfile
 import warnings
@@ -159,9 +160,7 @@ def convert(
         considered_joints: list[str] | None = None,
         plane_normal: tuple[float, float, float] = (0, 0, 1),
         heightmap: bool | None = None,
-        cameras: (
-            list[dict[str, str, str, str, str]] | dict[str, str, str, str, str]
-        ) = None,
+        cameras: list[dict[str, str]] | dict[str, str] = None,
     ) -> tuple[str, dict[str, Any]]:
         """
         Converts a ROD model to a Mujoco MJCF string.
@@ -479,7 +478,10 @@ def convert(
         # Add user-defined camera
         cameras = cameras if cameras is not None else {}
         for camera in cameras if isinstance(cameras, list) else [cameras]:
-            _ = ET.SubElement(worldbody_element, "camera", **camera)
+            mj_camera = MujocoCamera.build(**camera)
+            _ = ET.SubElement(
+                worldbody_element, "camera", dataclasses.asdict(mj_camera)
+            )
 
         # ------------------------------------------------
         # Add a light following the  CoM of the first link
@@ -515,9 +517,7 @@ def convert(
         model_name: str | None = None,
         plane_normal: tuple[float, float, float] = (0, 0, 1),
         heightmap: bool | None = None,
-        cameras: (
-            list[dict[str, str, str, str, str]] | dict[str, str, str, str, str]
-        ) = None,
+        cameras: list[dict[str, str]] | dict[str, str] = None,
     ) -> tuple[str, dict[str, Any]]:
         """
         Converts a URDF file to a Mujoco MJCF string.
@@ -559,9 +559,7 @@ def convert(
         model_name: str | None = None,
         plane_normal: tuple[float, float, float] = (0, 0, 1),
         heightmap: bool | None = None,
-        cameras: (
-            list[dict[str, str, str, str, str]] | dict[str, str, str, str, str]
-        ) = None,
+        cameras: list[dict[str, str]] | dict[str, str] = None,
     ) -> tuple[str, dict[str, Any]]:
         """
         Converts a SDF file to a Mujoco MJCF string.
@@ -593,3 +591,25 @@ def convert(
             heightmap=heightmap,
             cameras=cameras,
         )
+
+
+@dataclasses.dataclass
+class MujocoCamera:
+    name: str
+    mode: str
+    pos: str
+    xyaxes: str
+    fovy: str
+
+    @classmethod
+    def build(cls, **kwargs):
+        if not all(isinstance(value, str) for value in kwargs.values()):
+            raise ValueError("Values must be strings")
+
+        if len(kwargs["pos"].split()) != 3:
+            raise ValueError("pos must have three values separated by space")
+
+        if len(kwargs["xyaxes"].split()) != 6:
+            raise ValueError("xyaxes must have six values separated by space")
+
+        return cls(**kwargs)