fix: bugs and docs

Author: AlejandroFernandezLuces

src/ansys/tools/visualization_interface/backends/pyvista/pyvista.py

@@ -946,14 +946,24 @@ def add_text(
                 **kwargs
             )
         elif len(position) == 3:
-            # 3D world coordinates - use add_point_labels
-            import numpy as np
-            points = np.array([position])
-            actor = self._pl.scene.add_point_labels(
-                points,
-                [text],
-                font_size=font_size,
-                text_color=color,
+            # 3D world coordinates - create 3D text mesh
+            # We use Text3D instead of add_point_labels to avoid a bug in PyVista
+            # where it tries to access a non-existent _actors attribute
+
+            # Create 3D text object
+            text_mesh = pv.Text3D(text, depth=0.0)
+
+            # Scale text based on font_size (approximate scaling factor)
+            scale_factor = font_size / 100.0
+            text_mesh.points *= scale_factor
+
+            # Translate text to desired position
+            text_mesh.translate(position, inplace=True)
+
+            # Add text mesh to scene with specified color
+            actor = self._pl.scene.add_mesh(
+                text_mesh,
+                color=color,
                 **kwargs
             )
         else:

src/ansys/tools/visualization_interface/backends/pyvista/pyvista_interface.py

@@ -443,11 +443,19 @@ def show(
             jupyter_backend = "html"
 
         # Enabling anti-aliasing by default on scene
-        self.scene.enable_anti_aliasing("ssaa")
+        # Only enable if render_window is available (not None)
+        if hasattr(self.scene, 'render_window') and self.scene.render_window is not None:
+            self.scene.enable_anti_aliasing("ssaa")
 
         # If screenshot is requested, set off_screen to True for the plotter
         if kwargs.get("screenshot") is not None:
             self.scene.off_screen = True
+
+        # In off-screen mode (e.g., sphinx-gallery), prevent auto-close
+        # so the plotter can be reused
+        if self.scene.off_screen and 'auto_close' not in kwargs:
+            kwargs['auto_close'] = False
+
         if jupyter_backend:
             # Remove jupyter_backend from show options since we pass it manually
             kwargs.pop("jupyter_backend", None)