Houdini 22.0 Character KineFX

Dynamic motion

Add physically-accurate projectile motion to your animation in the animate state.

On this page

The dynamic motion tool in the animate state allows you to add physically-accurate projectile motion trajectories to your animation. See physics-based motion for more information.

To enter the dynamic motion tool, click on the top toolbar.

Create dynamic motion

To replace the current motion paths with dynamic motion:

  1. Select the center of mass control(s) to use for calculating the dynamic motion path.

  2. Click on the top toolbar or in the dynamic motion parameters, or press H in the viewport.

    To see the entire dynamic motion path, go to the dynamic motion settings and turn off Limit Number of Frames. The path of the current keyframed animation with rough posing will be shown.

    Animation trajectory with rough posing

  3. Set the start and end of a section of dynamic motion:

    • On the playbar timeline, move the animation to the start of the first jump, and click or press H over the viewport.

    • Move to the end of the first jump and click or press H over the viewport. The path of the first jump will be replaced with dynamic motion.

      or

    • Select a frame range by holding ⇧ Shift and dragging along the playbar timeline.

    • Click or press H in the viewport. Dynamic motion will be created between the start and end frames of the selection.

    Replace the original path with dynamic motion

  4. Add dynamic motion for the remaining jumps:

    Animation with dynamic motion

Put the dynamic motion back onto the animation

At this point, the dynamic motion can only be seen in the dynamic motion tool. To put the dynamic motion back onto the original animation, click Bake Keys in the animate state settings, Bake tab. The existing keys will be added to the dynamic motion path.

If Bake to New Layer is turned on, the keys will be added to a new override animation layer. If Bake to New Layer is turned off, the keys will be added to the current animation layer.

See the animate state settings for descriptions of the available baking options.

Adjust the start, end, and height of the dynamic motion

To adjust the start position, end position, and height of the dynamic motion, enter advanced mode in the dynamic motion tool:

  1. In the dynamic motion parameters, set Mode to Advanced.

  2. In the dialog that pops up, choose whether to work on a new animation layer or on the current layer. In advanced mode, changing the height of the dynamic motion results in the entire animation needing to be retimed. As a result, you are locked into working on one animation layer and will be prompted if you try to switch layers.

  3. In the Dynamic Motion Source Animation window, choose the character rig(s) you want the retiming to be applied to. For example, if you have a character throwing a ball in the air, select the rigs for both the character and the ball. In this way, if you increase the height of the ball’s dynamic motion arc, the character’s hand motion will also slow down to catch the ball.

  4. Click Accept.

    In advanced mode, the dynamic motion controls (start position, end position, and height) are displayed. You could set the visibility of these controls using selection sets - the dynamic motion controls are found under All Controls ▸ dynamicmotion.

  5. Adjust the height of the dynamic motion by selecting the height plane that appears at the top of the dynamic motion arc, and adjusting the handles:

    Change the height of the dynamic motion arc

    Note

    Select the height plane and press R to switch the transform handle to rotate mode. This allows you to rotate the plane so that the dynamic motion path skims the plane instead of reaching a specific height.

  6. Change the start or end position of a dynamic motion section by selecting the green/red arrow at the start/end of the dynamic motion path, and adjusting the position using the handle:

    Change dynamic motion end position

If you try to switch to another animation layer while in advanced mode, a prompt will appear with the following options:

Switch to <new layer>

Applies the dynamic motion changes to the new layer, and resets the current layer to the original animation.

Remain on <current layer>

Stays on the current animation layer.

Bake to new layer

Creates a new layer with the changes from the current layer.

Reset Dynamic Motion

Removes all dynamic motion, resetting the dynamic motion tool to its original state.

Note

If you switch from advanced mode to basic mode, the changes made in advanced mode since the last bake are discarded.

Dynamic motion parameters and settings

Dynamic motion parameters

In the dynamic motion tool, the following parameters are available in the Dynamic Motion tab of the animate state parameters:

Parameter / Button

Description

Creates a dynamic motion path.

Removes the current dynamic motion path.

Mode

In Basic mode, you can only add or remove dynamic motion. In Advanced mode, you can adjust the start, end, and height of the dynamic motion path.

Targeting Method

When Mode is set to Advanced, this allows you to adjust the dynamic motion path by controlling its height or duration.

Height Plane

Sets the dynamic motion path to reach the height plane at the top of the arc.

Life

Sets the dynamic motion path to span this amount of time.

Life

When Targeting Method is set to Life, this is the time from the start to the end of the dynamic motion path.

Dynamic motion settings

In the dynamic motion tool, the following settings are in the Dynamic Motion tab of the animate state settings:

Setting

Description

Reset Rig

Removes all dynamic motion.

Visible Controls

Determines the dynamic motion controls to display:

Current Motion

Displays the controls for the current dynamic motion path.

All Motion

Displays the controls for all the dynamic motion paths.

Limit Number of Frames

When turned on, limits the number of frames shown on the dynamic motion path. When turned off, displays the entire dynamic motion path.

Frames Before

When Limit Number of Frames is turned on, this is the number of frames to display before the current frame.

Frames After

When Limit Number of Frames is turned on, this is the number of frames to display after the current frame.

Toolbar options

On the top toolbar, the following buttons are specific to the dynamic motion tool. For descriptions of the general toolbar buttons, see the animate state toolbar.

Button

Description

Creates a dynamic motion path.

Removes the current dynamic motion path.

Basic / Advanced

Switch to advanced mode to adjust the start, end, and height of the dynamic motion.

Reset Rig

Removes all dynamic motion.

How-to

To...Do this

Display the entire dynamic motion path

In the dynamic motion settings, turn off Limit Number of Frames.

Limit the number of frames shown on the dynamic motion path

In the dynamic motion settings, turn on Limit Number of Frames, and adjust the Frames Before and Frames After values.

Adjust the height of the dynamic motion

Select the height plane that appears at the top of the dynamic motion arc and adjust the height using the handles.

or

  1. On the timeline, move the animation within the frame range of the dynamic motion section.

  2. In the dynamic motion parameters, adjust the Life value.

Change the start or end position of the dynamic motion section

Select the green/red arrow at the start/end of the dynamic motion path, and adjust the position using the handle.

Put the dynamic motion back onto the animation

In the animate state settings, Bake tab, click Bake Keys.

Display the controls for all the dynamic motion paths

In the dynamic motion settings, set Visible Controls to All Motions. The Visible Controls option is only applicable in advanced mode.

In the example below, the dynamic motion controls (start position, end position, and height) for the 3 balls are displayed:

Display all dynamic motion controls

You could also set the visibility of the dynamic motion controls using selection sets, found under All Controls ▸ dynamicmotion.

Remove a section of dynamic motion

  1. On the timeline, move the animation within the frame range of the dynamic motion section.

  2. Click on the top toolbar or in the dynamic motion parameters, or press ⌃ Ctrl + H over the viewport.

or

  1. Select a frame range by holding ⇧ Shift and dragging along the playbar timeline.

  2. Click or press ⌃ Ctrl + H in the viewport.

Remove all dynamic motion

On the top toolbar or in the dynamic motion settings, click Reset Rig.

Change the size of the dynamic motion path ticks

⇧ Shift +

Change the size of the dynamic motion height planes

⌃ Ctrl +

KineFX

Overview

Preparing character elements

Rigging with APEX graphs

  • APEX graph basics

    Introduction to the APEX graph evaluation framework.

  • APEX graph debugger

    Inspect the values of an APEX graph’s ports within the APEX network view.

  • APEX Script basics for graph building

    An overview of APEX Script, a code interface for building APEX graphs.

  • Graphs for numerical operations

    Example graphs of numerical operations like adding two values, fetching multiple results, and retrieving information from geometry.

  • Graphs for viewport animation

    Example graphs of animate state functionality like creating controls and constraints, and defining joint hierarchies.

  • Graphs for deforming geometry

    Example of a SOP network and APEX graph for deforming a 3-joint tube geometry.

  • Graph metadata

    Information added to graph nodes and ports.

  • APEX path pattern

    A set of rules that allow you to filter and select elements within graphs, skeletons, geometry, and the character folder structure.

  • APEX graph nodes

    APEX nodes provide operations for building up the functionality of APEX graphs, which are used in KineFX to create character rigs and perform other geometry manipulation.

  • APEX updates for H22

    New and updated APEX graph nodes for Houdini 22.

Building rig graphs with APEX Script

Rigging with rig components

Animating in the viewport

  • Animation workflow

    Example networks of adding characters, props, characters, and animation to a scene.

  • Animating in LOPs

    Rig and animate characters and props in the context of a USD stage.

  • Working in the animate state

    Select and manipulate controls, define transform limits for controls, and add skin controls to a character.

  • Animate state menus and HUDs

    Menus, HUDs, toolbars, and options in the animate state.

  • Animate state hotkeys

    Hotkeys available in the animate state.

  • Posing

    Pose characters in the animation scene by using locators, copying and pasting controls, and mirroring poses.

  • Motion paths

    Visualize the motion of controls as curves in 3D space.

  • Constraints

    Create relationships between controls in the animate state.

  • Dynamic motion

    Add physically-accurate projectile motion to your animation in the animate state.

  • Ragdoll

    Add a ragdoll simulation to your animation in the animate state.

  • Full body IK

    Apply full body inverse kinematics to pose the character using high-level targets rather than manipulating individual joints.

  • Secondary motion

    Add physically-accurate effects like lag/overshoot, jiggle, and spring to your animation in the animate state.

  • Control selection sets

    A tree view of controls, selections, and selection sets for the animate state. Allows management of control selection and visibility.

  • Motion mixer

    Combine and edit the animation clips of multiple characters in a timeline-based view.

  • Character picker

    Create a 2D layout with simple buttons for selecting character controls in an animation scene.

  • Animation catalog

    Save, manage, and apply animations and single-frame poses to an animation scene.

  • Animation layers

    Create multiple layers of animation without affecting the original animation.

  • Animation toolbar

    A customizable toolbar consisting of simple slider tools that quickly apply modifications to animation controls and curves.

  • Animation bookmarks

    Frame markers that help organize and identify the different parts of your animation.

Customizing the animate state

SOP-based animation

  • Physics-based motion

    Add physically-accurate motion to your animation using the Projectile Motion and Pendulum Motion SOPs.

  • Ragdoll simulations

    Add a ragdoll simulation to your animation using the Ragdoll Solver SOP.

Deformation

  • Blend shapes

    Create blend shapes using blend shape SOP nodes.

Animation retargeting

Pre-H20

Panes

  • Motion mixer

    A timeline-based view of the animation clips and motion effects of multiple characters.

  • Character picker

    Create a 2D layout with simple buttons to select character controls in an animation scene.

  • Rig tree view

    A hierarchical view of character components, including packed character folders, KineFX rigs, and Object node rigs.

  • Animation editor

    View and edit animated parameters and their transitions between keyframes.

  • Geometry spreadsheet

    Displays details about the geometry selected in the network editor.

Appendix