Adding logic for custom cameras in USD

python/mujoco/testdata/usd_golden.usda

@@ -14,7 +14,7 @@ def Xform "World"
     def Xform "Light_Xform_0"
     {
         double3 xformOp:translate.timeSamples = {
-            0: (0, -3.674234628677368, 3.674234628677368),
+            0: (0, -6, 0),
         }
         uniform token[] xformOpOrder = ["xformOp:translate"]
 
@@ -28,6 +28,22 @@ def Xform "World"
         }
     }
 
+    def Xform "Camera_Xform_primary_camera"
+    {
+        matrix4d xformOp:transform.timeSamples = {
+            0: ( (1, 0, -0, 0), (0, 0.009999499656260014, 0.9999499917030334, 0), (0, -0.9999499917030334, 0.009999499656260014, 0), (0, -6, 0, 1) ),
+        }
+        uniform token[] xformOpOrder = ["xformOp:transform"]
+
+        def Camera "Camera_primary_camera"
+        {
+            float2 clippingRange = (0.0001, 1000000)
+            float focalLength = 12
+            float focusDistance = 400
+            float horizontalAperture = 12
+        }
+    }
+
     def Xform "Camera_Xform_closeup"
     {
         matrix4d xformOp:transform.timeSamples = {

python/mujoco/usd/camera.py

@@ -14,6 +14,8 @@
 # ==============================================================================
 """Camera handling for USD exporter."""
 
+from typing import List, Optional, Tuple
+
 import mujoco.usd.utils as utils_module
 
 import numpy as np
@@ -24,15 +26,16 @@
 from pxr import Usd
 from pxr import UsdGeom
 
+import mujoco.usd.utils as utils_module
 
 class USDCamera:
-  """Class that handles the cameras in the USD scene."""
-
-  def __init__(self, stage: Usd.Stage, obj_name: str):
+  """Class that handles the cameras in the USD scene"""
+  
+  def __init__(self, stage: Usd.Stage, camera_name: str):
     self.stage = stage
 
-    xform_path = f"/World/Camera_Xform_{obj_name}"
-    camera_path = f"{xform_path}/Camera_{obj_name}"
+    xform_path = f"/World/Camera_Xform_{camera_name}"
+    camera_path = f"{xform_path}/Camera_{camera_name}"
     self.usd_xform = UsdGeom.Xform.Define(stage, xform_path)
     self.usd_camera = UsdGeom.Camera.Define(stage, camera_path)
     self.usd_prim = stage.GetPrimAtPath(camera_path)

python/mujoco/usd/demo.py

@@ -31,16 +31,18 @@ def generate_usd_trajectory(local_args):
   # create an instance of the USDExporter
   exp = exporter.USDExporter(
       model=m,
-      output_directory_name=pathlib.Path(local_args.model_path).stem,
+      output_directory=pathlib.Path(local_args.model_path).stem,
       output_directory_root=local_args.output_directory_root,
       camera_names=local_args.camera_names,
   )
 
+  cam = mujoco.MjvCamera()
+
   # step through the simulation for the given duration of time
   while d.time < local_args.duration:
     mujoco.mj_step(m, d)
     if exp.frame_count < d.time * local_args.framerate:
-      exp.update_scene(data=d)
+      exp.update_scene(data=d, camera=cam)
 
   exp.add_light(pos=(0, 0, 0),
                 intensity=2000,