Viewport
The viewport is the 3D rendering window that displays your composed stage using the Hydra rendering framework. usdtweak supports up to four independent viewports, each with its own camera and display settings.
Camera controls
Orbit mode (default)
| Action | Input |
|---|---|
| Orbit | Middle-click + drag |
| Pan | Shift + middle-click + drag |
| Zoom | Scroll wheel |
Fly mode
Fly mode provides first-person camera navigation using keyboard and mouse:
| Action | Input |
|---|---|
| Move forward | W |
| Move backward | S |
| Strafe left | A |
| Strafe right | D |
The fly speed can be adjusted in the viewport settings popup (the monitor icon in the toolbar) under Camera fly speed.
Framing
- Frame selection -- Automatically moves the camera to frame the currently selected prim.
- Frame root prim -- Resets the camera to frame the entire scene.
Manipulators
The manipulator toolbox appears on the left side of the viewport when any viewport is open. It provides four modes:
| Manipulator | Description |
|---|---|
| Select (arrow icon) | Click to select prims in the viewport. No transform gizmo shown. |
| Translate (arrows icon) | Move prims along axes or planes using the position gizmo. |
| Rotate (circular arrows icon) | Rotate prims around axes using the rotation gizmo. |
| Scale (compress icon) | Scale prims along axes. Hold Shift for uniform scaling. |
Click the corresponding button in the toolbox, or use the toolbar buttons within the viewport itself, to switch modes.
Pick modes
The pick mode controls how clicking in the viewport resolves to a prim selection:
| Mode | Behavior |
|---|---|
| Prim (P) | Selects the exact prim whose geometry was clicked. |
| Model (M) | Walks up the hierarchy to the nearest prim with kind = model (or a model-derived kind). |
| Assembly (A) | Walks up the hierarchy to the nearest prim with kind = assembly. |
The pick mode button is displayed in the viewport toolbar and in the manipulator toolbox.
Viewport toolbar
The toolbar runs along the top of the viewport and provides quick access to rendering and display options (left to right):
Hydra enable/disable
The film icon toggles Hydra rendering on or off for the current stage. Disabling Hydra is useful when you only need the layer editing panels and want to avoid the rendering overhead.
Renderer selection
Shows the current Hydra render delegate (typically Storm). Click to switch between available renderers if multiple are installed.
Pick mode
Described above. Controls how viewport clicks resolve to prim selections.
Renderer settings
The gear icon opens a popup with detailed renderer controls:
- Renderer -- Select the render delegate
- Color correction -- sRGB or disabled
- AOV selection -- Choose which render output to display (color, depth, etc.)
- Renderer commands -- Renderer-specific actions
- Renderer settings -- Renderer-specific parameters
Viewport settings
The monitor icon opens display settings:
- Background color -- Set the viewport background
- Draw mode -- Choose how geometry is rendered:
- Points
- Wireframe
- Wireframe on surface
- Shaded flat
- Shaded smooth (default)
- Geometry only
- Geometry flat
- Geometry smooth
- Complexity -- Adjust subdivision/tessellation LOD (1.0 to 1.4)
- Show purpose -- Toggle visibility of geometry by USD purpose: guides, proxy, render
- Highlight selection -- Enable or disable selection highlighting
- Enable lighting -- Toggle lighting calculations
- Enable scene materials -- Toggle material rendering
- Enable scene lights -- Toggle scene-authored lights
- Enable USD draw modes -- Respect draw mode opinions on prims
- Enable camera light -- Toggle the camera-attached headlight
- Show grid -- Toggle the ground grid
- Show gizmos -- Toggle transform gizmos
- Camera fly speed -- Adjust the speed of fly-mode navigation
- Show menu bar -- Toggle the viewport's menu bar (an alternative layout for accessing these settings)
Camera light toggle
The flame icon toggles the camera-attached headlight on or off.
Scene materials toggle
The sparkle icon toggles scene material rendering. When disabled, geometry is shown with a default grey material, which can improve viewport performance.
Camera selection
Shows the current camera name. Click to open the camera list:
Built-in cameras:
- Perspective
- Top
- Bottom
- Front
- Back
- Left
- Right
Stage cameras: Any UsdGeomCamera prims found in your stage are also listed and can be selected.
The camera popup also includes a camera editor for adjusting parameters of the selected camera.
Multiple viewports
usdtweak supports up to four simultaneous viewports (Viewport1 through Viewport4). Enable additional viewports from the Windows menu. Each viewport has its own camera, renderer settings, and display options, so you can view your scene from multiple angles or with different rendering configurations at the same time.
Viewport menu bar
As an alternative to the toolbar buttons, you can enable a traditional menu bar at the top of the viewport via the viewport settings popup (Show menu bar checkbox). The menu bar provides the same options organized under Renderer, Viewport, and Cameras menus.