Zero Gravity

Overview

When placing many objects in a natural way, the Zero Gravity tool can ease this burden. Designed to use physics interactions while editing, users can now nudge, slide bump and push objects into position. Making a shelf full of doodads is now as easy as click and drag.

Introductory Video

This video offers a quick introduction to Omniverse’s Zero Gravity Extension and offers help on enabling the extension and general usage.

Set Up

Enable the Extension

Using the Omniverse Zero Gravity Tool begins with enabling the extension.

Check if Enabled

You can quickly see if the extension is already loaded by looking at the toolbar.

../_images/ext_physics-placement_toolbar-icon.png

If your toolbar displays with the above icon appearing; the Zero Gravity extension is enabled.

Note

Omniverse Create has the Zero Gravity Extension enabled by default.

Enable

To enable the extension

../_images/ext_physics-placement_enable-extension.png
  1. Navigate to window > extensions

  2. In the search bar enter Zero Gravity

  3. Locate the Zero Gravity extension and select it.

  4. Select the Enabled toggle to enable the extension.

  5. Select the Check Mark next to auto-load to Load the Extension Automatically on App Start if desired.

  6. Close the Extensions Panel.

At this point the extension should be enabled and you should now see the tool’s icon on the leftmost toolbar.

User Guide

../_images/ext_zero-gravity_flyouts.png

Enable Zero Gravity Mode

To enable Zero Gravity Mode, Simply Select the tool’s icon. While Active, the icon will be Dark Grey.

../_images/ext_physics-placement_toolbar-icon_enabled.png

Note

You can enable the Zero Gravity tool with the X Hotkey.

When selecting the Zero Gravity tool, notice that your stage may be updated with a Temporary Physics Scene. This temporary physics scene will be removed when the tool is disabled. If a physics scene already exists, the Zero Gravity tool will utilize the existing physics scene.

Action Bar

Upon enabling the Zero Gravity tool, the Zero Gravity action bar will appear. This action bar allows you to clear and set markers, drop assets and access additional settings related to the Zero Gravity tool.

../_images/ext_physics-placement_action-bar.png

Action

Description

Clear Marker(s)

Removes all Zero Gravity physics on on selected assets.

Set Static Marker(s)

Sets selected assets as non-moveable

Set Dynamic Marker(s)

Sets selected assets to be moveable.

Start/Stop Dropping

Toggles simulated gravity on selected dynamic assets.

Settings

Additional options.

Note

The Zero Gravity tool only works on assets with geometry.

Marker Types

Markers act as a set of rules for your asset to follow during editing. They can broadly be termed as either static or dynamic which will set them to either non-moveable or moveable respectively. Each of these types have different detail levels which allow for control over accuracy and speed of simulation.

Option

Result

Set Static Markers

Non-Moveable Colliders, Asset(s) become outlined in Red
  • Simplified Mesh

Mesh Simplification Approximation
  • Exact Mesh

Use Triangle Mesh, No Approximation

Set Dynamic Markers

Moveable Colliders, Asset(s) become outlined in Green
  • Good Approximation

Convex Hull Approximation
  • Better Approximation

Convex Decomposition Approximation

Note

Overlapping assets set to Dynamic will become outlined in Purple. They will remain purple and will not interact with each other until the assets are no longer overlapping. Once the overlap issue is resolved, they will return to a green outlined and the Zero Gravity tool will again work as expected.

Setting Zero Gravity Markers

Before setting a Zero Gravity Marker on an asset in your Stage, objects will move, rotate and scale as they normally would. In order for physics to be applied to an asset, users are required to Mark the asset for it’s intended purpose.

To apply a Zero Gravity Marker

  1. Ensure the Zero Gravity tool is Enabled.

  2. Select an Asset in the Viewport or Stage.

  3. Select one of the Static or Dynamic choices found in the Action Bar.

Note

While set to Static, objects can not be moved with the transform gizmo. To temporarily allow movement, simply disable the Zero Gravity tool and re-enable when moving/positioning the asset is complete.

Zero Gravity Settings

The options menu is revealed by right clicking on the Zero Gravity tool icon or selecting the option in the Action Bar. Options within this menu only affect the Zero Gravity tool, no other tools (including other physics tools) are affected.

../_images/ext_physics-placement_action-bar_options.png ../_images/ext_physics-placement_toolbar-icon_right-click.png

Toggle Option

Result

Move-Lock Rotation

Toggles to prevent moved assets from rotating.

Show Dynamic Markers

Outlines Dynamic Objects in Green

Show Static Markers

Outlines Static Objects in Red

Clear All Markers

Removes ALL Zero Gravity Assignments (See Note Below)

Note

The Clear All Marker option is only available when the Physics Zero Gravity tool is enabled.

Positioning Assets

Moving and Rotating Assets

Using the move and rotate tools will allow users to move any selected assets with dynamic markers and will simulate physical interaction with other marked assets. Rotation of selected assets can be disabled in the options menu.

Positional Scale

While the Zero Gravity tool is enabled, the Scale tool is transformed into the Positional Scale Tool. Instead of scaling the geometry of objects, the Positional Scale tool allows you to scale the positions of multiple objects. This can help to group and position objects quickly for dropping purposes.

Note

If you have the need to scale assets traditionally, simply disable the Zero Gravity tool Scale and re-enable.

Shift-Drag Simulation

The Physics Zero Gravity tool can be used to nudge things around and help place assets in a more quick natural way. When the Zero Gravity tool is enabled, Using move + shift on an asset Marked with a dynamic option will allow a simulated move.

  1. Ensure Zero Gravity Mode is Enabled.

  2. Select any asset with a dynamic Zero Gravity tool marker. (Outlined in Green)

  3. Select the Move Tool

  4. Holding Shift, Drag any assets with masked as dynamic.

  5. Notice the selected assets will interact with other assets marked as static (Outlined in Red) and dynamic assets (Outlined in Green) differently.

Drop Simulation

Dropped objects will fall and collide with other geometry that have Zero Gravity Markers set on them. Static objects will block and push the dropped object(s) while dynamic objects will be nudged and pushed.

To Drop Geometry…

  1. Ensure Physics Zero Gravity Mode is Enabled.

  2. Select any asset with a dynamic marker. (Outlined in Green)

  3. While Still Selected (Outlined in Orange) press the END key.

  4. Notice the selected assets will fall and interact with other Zero Gravity marked assets marked as static (Outlined in Red) and dynamic assets (Outlined in Green) differently.

Saving Zero Gravity Mode Changes

When saving your USD file, all relevant information pertaining to Zero Gravity is kept and stored as expected. The temporary physics data used by Zero Gravity will be removed keeping your scene un-affected.