[HDRP] Fix issue when changing FoV with the physical camera fold-out closed

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -96,6 +96,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue causing errors in GenerateMaxZ when opaque objects or decals are disabled. 
 - Fixed an issue with Bake button of Reflection Probe when in custom mode
 - Fixed exceptions related to the debug display settings when changing the default frame settings.
+- Fixed issue when changing FoV with the physical camera fold-out closed.
 
 ### Changed
 - Combined occlusion meshes into one to reduce draw calls and state changes with XR single-pass.

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/Camera/HDCameraUI.Drawers.cs

@@ -284,6 +284,18 @@ static void Drawer_Projection(SerializedHDCamera p, Editor owner)
                         ? s_FovLastValue
                         : Camera.HorizontalToVerticalFieldOfView(s_FovLastValue, (p.serializedObject.targetObjects[0] as Camera).aspect);
                 }
+                else if (s_FovChanged && isPhysicalCamera && !p.projectionMatrixMode.hasMultipleDifferentValues)
+                {
+                    // If we have a physical camera, we should also update the focal length here, because the
+                    // Drawer_PhysicalCamera will not be executed if the physical camera fold-out is closed
+                    cam.verticalFOV.floatValue = fovAxisVertical
+                        ? s_FovLastValue
+                        : Camera.HorizontalToVerticalFieldOfView(s_FovLastValue, (p.serializedObject.targetObjects[0] as Camera).aspect);
+
+                    float sensorLength = cam.fovAxisMode.intValue == 0 ? cam.sensorSize.vector2Value.y : cam.sensorSize.vector2Value.x;
+                    float focalLengthVal = Camera.FieldOfViewToFocalLength(s_FovLastValue, sensorLength);
+                    cam.focalLength.floatValue = EditorGUILayout.FloatField(focalLengthContent, focalLengthVal);
+                }
 
                 EditorGUILayout.Space();
             }