Implemented shadow linking for the scene graph view in GL.

Fixed bug in Create LOD LOP that would cause it to remove parts of the scene graph.

Fixed a crash in Copy to Points 2.0 SOP in certain cases where the Source Group is an edge group, vertex group, or some invalid group strings.

Reorganized parameter layouts for SOP Import, SOP Create, and SOP Modify LOP nodes, and the USD Configure SOP. Made important parameters more easily accessible.

Added support for exporting geometry array attributes to USD and round-tripping back to SOPs. Array attributes are represented as a pair of primvars (a list of array lengths, and a long array of the concatenated values with constant interpolation).

Gas Geometry/Option Transfer DOP now accepts a space-separated list of attribute and option names (though the type is shared between them).

Prevent the viewport command Restart Renderer from causing a crash if the renderer is currently updating in the background. The restart will be deferred until the update finishes.

The FEM Fuse Constraint now offers a more procedural method for constraining points together. The user may specify identifier attributes, where points that have the same identifier will be constrained to each other. This works both within a single DOP object and between distinct DOP objects. As an example, this can be used to create composite objects with hard transitions between material settings. Another use-case is procedural FEM fracturing, where the identifier attributes are modified in a SOP Solver.

Added an option to the USD Render ROP to wait until the render completes, even for a single frame render.

Fixed a macOS-only bug in the Python 3 build where MPlay sometimes crashed when launched by a render in Houdini.

Fixed a macOS-only bug where Houdini sometimes spawned the Image Viewer or License Administrator app from another Houdini distribution installed on the system.

Fixed issue that caused hkey and sesictrl to miss report an invalid server code error when connected to an external license server.

Fixed bug where stashed view transforms from a different global orientation could be used when changing viewport types.

Light LOP state primpath bug fix. Added mode state menu. Orientation and intensity keep toggles now in state menu as well.

Added parameters to the USD Render ROP to control checkpointing (periodic saving of the image generated so far) and the ability to enable the periodic output of statistics from the renderer.

HOM now has support for vertex groups.

Added transferring of detail, primitive, and vertex attributes from the curves in the Copy to Curves SOP.

Fixed bug that would cause hkey to display the same error message in hkey and in the third party login browser.

Added an adaptive pressure solver to the FLIP Solver. This can be enabled by selecting "Solve Pressure With Adaptivity" option in the Solve tab. This new solver offers significant performance improvements for large tank simulations.

Fixed a bug where calling the `hou.ui.selectFile()` HOM function with the `file_type` argument set to `hou.fileType.Hip` opened a file chooser that failed to list *.hipnc and *.hiplc files.

Shotgun Find: Added the ability to rename the output attribute.

Fixed a bug in the handling of deferred Qt events that could result in events being sent to deleted objects.

Background images are now drawn at a depth to prevent clipping by the near or far planes in the fixed orthographic views when not auto-placing.