SMR Inverse Kinematics (IK)

In the article below:

Introduction

After multiple failed attempts at IK by others over the years (the most notorious being Adobe's own implementation of bones), the Electric Dog team has developed and delivered a fully-fledged, flexible and polished IK system.

For the first time Flash / Animate users can enjoy the benefits of easy, fast and functional IK posing.
SMR IK is an extension to the existing SMR FK system and both Forward and Inverse Kinematics are available at all times, allowing the animator to block out and refine the poses, using the whole arsenal of tools without the need to switch between FK and IK modes.

For the first time in the history of Flash Animation feet can be pinned to the ground and the torso can be pulled down to make the character squat!

Overview

SMR Inverse Kinematics is the next big step in the evolution of the Smart Magnet Rig ™ system, building upon our hugely popular FK tools and giving unseen before level of flexibility and control to all Flash and Animate users.

Contrary to Adobe's failed Bone tool / Armature approach, SMR IK is a professional-grade IK implementation which uses the hierarchical SMR structures to facilitate IK transformations and easier, more-intuitive-than-ever posing of digital cutout rigs (puppets).

SMR IK was designed and developed from the ground up with the needs of the animation professional in mind.

SMR IK is part of EDAP Tools Premium v.6.0 and newer.
It integrates seamlessly with SMR FK. No additional work needs to be done on existing SM Rigs to start enjoying all the benefits that Inverse Kinematics brings.
Animators who have started a project using the free version of EDAP Tools can upgrade to Premium at any moment and get access to IK controls.

What does SMR IK bring to the animation process?

SMR IK allows animators to pose more intuitively and have full control over the most subtle aspects of the character's gestures.
Limbs can be adjusted from the wrist and the ankle; the whole torso can be moved or rotated while feet remain planted on the ground; the center of gravity can be shifted from one foot to the other by just pulling the body.

All the above is available simultaneously alongside SMR FK and no switching between the two modes is needed.

The UX is extremely intuitive and consistent with the established SMR FK conventions and methods. Posing with SMR IK is fast and enjoyable. The combination of hard and soft FK / IK rotations results in effortlessly achieved organic-looking poses.

SMR IK works with Macromedia Flash 8, all versions of Adobe Flash CS and the 4 most recent versions of Adobe Animate.

To Flash users unwilling to move on to Adobe's subscription model, SMR IK brings a feature set that they could not even dream of, making Flash 8 or CS6 literally as good, if not better than the latest Animate.

All our videos are 1080p. If for some reason full HD is not available here, try watching them on youtube.

How does it work?

The character has to be rigged as a Smart Magnet Rig, using one of the available rigging methods. This creates a hierarchical SMR structure, which is realized at the level of Symbol instance. The rig elements contain SMR info – metadata, describing each element's position in the hierarchy and its relationship with the others.
This metadata is then interpreted by the various SMR tools, such as KineFlex, to create FK and IK chains and transformations.

A SMR IK chain consists of strictly two elements. The second element in the chain must have a Magnet Target.
IK transformations are controlled via SMR Effectors.

The SMR Effector can contain additional information about the IK chain, such as joint constraints.
Effectors have several different states, which are described in detail further down in this article.

IK transformations can also be controlled by dragging an element preceding the first one in the IK chain.
In these Reverse IK (RIK) transformations the Effectors work as Gravity/Pins.

Are there any special requirements?

A SMR IK chain consists of two elements.
For example: Upper leg and lower leg – respectively element 1 and element 2.

A Magnet Target must be present in the second element of the IK chain.
The Effector which controls the chain attaches to this Magnet Target.

SMR IK tools and interactions

• SMR Controllers
• SMR KineFlex
• SMR Helpers panel

SMR Controllers

SMR Controllers are EDAPT Objects, which are used as handles or pins to control SMR IK chains with the KineFlex tool.

Types of Controllers
There are two types of Controllers – Effectors and Braces.
SMR Effectors are used as handles or pins to control SMR IK chains.
SMR Braces are used to move or rotate multiple SMR Effectors simultaneously.

Creating Controllers
SMR Controllers are created by Create And Manage IK Objects (SMR) – a dedicated command, which can be invoked via a keyboard shortcut Shift+F1(effector) or chosen from the Commands menu.
SMR Effectors and Braces can also be created by pressing the dedicated buttons and in SMR Helpers panel.

If before calling Create And Manage IK Objects, suitable SMR elements were selected, Controllers are automatically attached to these elements upon creation.

The default size, color and opacity of Controllers can be set in the command's settings in EDAPT Control Panel or Quick Settings F12.

Controller layer(s)
Controllers occupy a guided layer, called SMR_Controllers.
Users can manually create additional SMR_Controllers layers, where they can separate Controllers into groups for convenience.

Controller layer(s) can be hidden and shown, i.e. their visibility toggled ON or OFF via a convenient shortcut F1(visibility). The opacity of all controllers can also be easily decreased and increased by pressing Ctrl+F1(opacity) repeatedly.

SMR Controllers on locked layer(s) are still active, while controllers on hidden layers do not interact with the SM Rig.
To function Controllers must always be placed on layers called SMR_Controllers.

Effectors

Attaching and detaching
SMR Effectors can be attached and detached from elements by dragging them with KineFlex while holding down the Shift key.
When released over a suitable element, (part of a Smart Magnet Rig, MT present) the Effector will snap to its Magnet Target and can be dragged to control the IK chain or configured further with Joint range constraints or changing its state and direction.

Effector states
SMR Effectors have 3 functionally different states, which are reflected in their look:

• Detached
• Attached, RIK Active (The Effector works as Gravity/Pin during RIK transformations)
• Attached, RIK Inactive (The Effector is invisible to the RIK transformation)

Users can switch between the two attached states either by Alt+Shift-clicking on an Effector with the KineFlex or by pressing the dedicated button in SMR Helpers panel.

Direction
Attached Effectors have direction which is visualized by a clockwise or counter-clockwise arrow. The arrow is a visual indicator of the direction in which the IK chain will bend at the joint between element 1 and element 2. The direction of the Effector can be switched by simply flipping the Effector horizontally, keyboard shortcut [ H ].

Joint range constraints
Effectors can contain information about joint constraints.
When dropped over a suitable element the Effector detects the angle between the elements of the IK chain and automatically sets this value as its Max joint range constraint.
Constraints can be set and edited via Effector Properties dialog, and can also be saved as presets. The Effector Properties dialog for the selected Effector is called via a shortcut Alt+G(effector properties) or by pressing the dedicated button in SMR Helpers panel.

Magnetic snapping
Attached SMR Effectors will automatically snap back to their controlled element when dragged with KineFlex and released. Additionally snapping can be achieved in two ways:

1. Using Smart Magnet Joint: If nothing or only Effectors are selected on the Stage, press `(tilda/~ key to the left of 1/! and below Esc) and all Effectors will snap to their respective controlled elements.
2. Using Create And Manage IK Objects: Hide and show Effectors by pressing F1(visibility) twice. When set to visible all Effectors will snap into place.

Reverse snapping of the whole character rig to one selected Effector is done by Smart Magnet Joint: Select one Effector and press Ctrl+`(inverse) – the whole rig will reassemble fully around the selected Effector.

Reverse snapping, preserving relative positions of elements is done via the SMR Helpers panel:

• Selecting one Effector on Stage and pressing the Move/Solve button .
• Selecting one or two elements of an IK chain and pressing the Move/Solve button .

Movement
When dragged with the KineFlex tool, Attached SMR Effectors control their respective IK chains by adjusting the angle between the elements and the direction of the whole chain (IK transformation).
When an element preceding the first one in the IK chain is dragged with the KineFlex tool the Effectors work as Gravity/Pins (RIK transformation).

Braces

SMR Braces serve as higher-level controllers to move or rotate multiple SMR Effectors simultaneously.

To link Effectors to a Brace, select the Effectors on the Stage and click on Brace's [ ··· ] button with KineFlex. In the dialog box that pops up choose Link.
To unlink Effectors, select one or more Effectors which belong to a Brace group on the Stage, click on the [ ··· ] button with KineFlex, and in the dialog choose Unlink.

To move a Brace with all its linked Effectors drag one of its diamond-shaped handles with KineFlex.
To rotate a Brace with all its linked Effectors use the circular handle.

SMR KineFlex

SMR KineFlex is used mainly for posing character rigs for animation.
When used to drag elements of a Smart Magnet Rig in the absence of SMR Controllers, the result is Forward Kinematics transformations.
When used to drag SMR Controllers or elements at the opposite sides of IK chains, the result is Inverse Kinematics transformations.

KineFlex can also be used to attach and detach SMR Controllers or switch between Effector states.

KineFlex behavior is altered by the following modifier keys: Alt, Shift, Alt+Shift.

Interactions:

• Drag a SMR Effector – IK transformation of the controlled IK chain.
• Alt-drag a SMR Effector – same as above, but the elements after the controller do not soft-rotate.
• Shift-drag Attached Effector will detach it.
• Shift-drag a Detached Effector over a suitable SMR element will attach it upon release.
• Drag an element preceding the first one in an IK chain when Effectors are present – RIK rotation, Effectors serve as Gravity/Pins.
• Alt-drag an element preceding the first one in an IK chain when Effectors are present – RIK rotation with all elements beyond the IK chains in hard rotation, Effectors serve as Gravity/Pins.
• Shift-drag an element preceding the first one in an IK chain when Effectors are present – RIK move, Effectors serve as Gravity/Pins.
• Alt+Shift-click on SMR Effector – switches the effector state; alternates between RIK Active and RIK Inactive

SMR Helpers panel

SMR Helpers panel contains a set of buttons, which allow alternative access to various IK-related functions.
It also contains some buttons, which trigger unique functions and can only be called from the panel.

Unique functions:
IK joint constraints Presets Manager – edit, delete and apply joint presets.
IK Clean Up – cleans up the arcs of pinned elements, broken during Classic Tweens.
Move/Solve – snaps the whole rig to a selected Effector; when a RIK element is selected resolves all IK chains.

Buttons available for convenience:
Create SMR Effector
Create SMR Brace
Switch Effector state – toggles Attached Effectors between RIK Active and RIK Inactive
Controller properties – invokes Controller Properties dialog
Toggle Controller layer(s) visibility
Adjust Controllers opacity

How to use SMR IK

Below is a video demonstration, showing a few typical uses of SMR FK and IK.

All our videos are 1080p. If for some reason full HD is not available here, try watching them on youtube.