godot/doc/classes/SkeletonModification2DCCDIK.xml
TwistedTwigleg 8aa3c2f091 New and improved IK system for Skeleton2D
This PR and commit adds a new IK system for 2D with the Skeleton2D node
that adds several new IK solvers, a way to control bones in a Skeleton2D
node similar to that in Skeleton3D. It also adds additional changes
and functionality.

This work was sponsored by GSoC 2020 and TwistedTwigleg.

Full list of changes:
* Adds a SkeletonModifier2D resource
  * This resource is the base where all IK code is written and executed
  * Has a function for clamping angles, since it is so commonly used
  * Modifiers are unique when duplicated so it works with instancing
* Adds a SkeletonModifierStack2D resource
  * This resource manages a series of SkeletonModification2Ds
  * This is what the Skeleton2D directly interfaces with to make IK possible
* Adds SkeletonModifier2D resources for LookAt, CCDIK, FABRIK, Jiggle, and TwoBoneIK
  * Each modification is in its own file
  * There is also a SkeletonModifier2D resource that acts as a stack for using multiple stacks together
* Adds a PhysicalBone2D node
  * Works similar to the PhysicalBone3D node, but uses a RigidBody2D node
* Changes to Skeleton2D listed below:
  * Skeleton2D now holds a single SkeletonModificationStack2D for IK
  * Skeleton2D now has a local_pose_override, which overrides the Bone2D position similar to how the overrides work in Skeleton3D
* Changes to Bone2D listed below:
  * The default_length property has been changed to length. Length is the length of the bone to its child bone node
  * New bone_angle property, which is the angle the bone has to its first child bone node
  * Bone2D caches its transform when not modified by IK for IK interpolation purposes
  * Bone2D draws its own editor gizmo, though this is stated to change in the future
* Changes to CanvasItemEditor listed below:
  * Bone2D gizmo drawing code removed
  * The 2D IK code is removed. Now Bone2D is the only bone system for 2D
* Transform2D now has a looking_at function for rotating to face a position
* Two new node notifications: NOTIFICATION_EDITOR_PRE_SAVE and NOTIFICATION_EDITOR_POST_SAVE
  * These notifications only are called in the editor right before and after saving a scene
  * Needed for not saving the IK position when executing IK in the editor
* Documentation for all the changes listed above.
2021-06-05 15:19:51 -04:00

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XML

<?xml version="1.0" encoding="UTF-8" ?>
<class name="SkeletonModification2DCCDIK" inherits="SkeletonModification2D" version="4.0">
<brief_description>
A modification that uses CCDIK to manipulate a series of bones to reach a target in 2D.
</brief_description>
<description>
This [SkeletonModification2D] uses an algorithm called [b]C[/b]yclic [b]C[/b]oordinate [b]D[/b]escent [b]I[/b]nverse [b]K[/b]inematics, or CCDIK, to maniuplate a chain of bones in a [Skeleton2D] so it reaches a defined target.
CCDIK works by rotating a set of bones, typically called a "bone chain", on a single axis. Each bone is rotated to face the target from the tip (by default), which over a chain of bones allow it to rotate properly to reach the target. Because the bones only rotate on a single axis, CCDIK [i]can[/i] look more robotic than other IK solvers.
[b]Note:[/b] The CCDIK modifier has [code]ccdik_joints[/code], which are the data objects that hold the data for each joint in the CCDIK chain. This is different from a bone! CCDIK joints hold the data needed for each bone in the bone chain used by CCDIK.
CCDIK also fully supports angle constraints, allowing for more control over how a solution is met.
</description>
<tutorials>
</tutorials>
<methods>
<method name="get_ccdik_joint_bone2d_node" qualifiers="const">
<return type="NodePath">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns the [Bone2D] node assigned to the CCDIK joint at [code]joint_idx[/code].
</description>
</method>
<method name="get_ccdik_joint_bone_index" qualifiers="const">
<return type="int">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns the index of the [Bone2D] node assigned to the CCDIK joint at [code]joint_idx[/code].
</description>
</method>
<method name="get_ccdik_joint_constraint_angle_invert" qualifiers="const">
<return type="bool">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns whether the CCDIK joint at [code]joint_idx[/code] uses an inverted joint constraint. See [method set_ccdik_joint_constraint_angle_invert] for details.
</description>
</method>
<method name="get_ccdik_joint_constraint_angle_max" qualifiers="const">
<return type="float">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns the maximum angle constraint for the joint at [code]joint_idx[/code].
</description>
</method>
<method name="get_ccdik_joint_constraint_angle_min" qualifiers="const">
<return type="float">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns the minimum angle constraint for the joint at [code]joint_idx[/code].
</description>
</method>
<method name="get_ccdik_joint_enable_constraint" qualifiers="const">
<return type="bool">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns whether angle constraints on the CCDIK joint at [code]joint_idx[/code] are enabled.
</description>
</method>
<method name="get_ccdik_joint_rotate_from_joint" qualifiers="const">
<return type="bool">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<description>
Returns whether the joint at [code]joint_idx[/code] is set to rotate from the joint, [code]true[/code], or to rotate from the tip, [code]false[/code]. The default is to rotate from the tip.
</description>
</method>
<method name="set_ccdik_joint_bone2d_node">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="bone2d_nodepath" type="NodePath">
</argument>
<description>
Sets the [Bone2D] node assigned to the CCDIK joint at [code]joint_idx[/code].
</description>
</method>
<method name="set_ccdik_joint_bone_index">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="bone_idx" type="int">
</argument>
<description>
Sets the bone index, [code]bone_index[/code], of the CCDIK joint at [code]joint_idx[/code]. When possible, this will also update the [code]bone2d_node[/code] of the CCDIK joint based on data provided by the linked skeleton.
</description>
</method>
<method name="set_ccdik_joint_constraint_angle_invert">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="invert" type="bool">
</argument>
<description>
Sets whether the CCDIK joint at [code]joint_idx[/code] uses an inverted joint constraint.
An inverted joint constraint only constraints the CCDIK joint to the angles [i]outside of[/i] the inputted minimum and maximum angles. For this reason, it is referred to as an inverted joint constraint, as it constraints the joint to the outside of the inputted values.
</description>
</method>
<method name="set_ccdik_joint_constraint_angle_max">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="angle_max" type="float">
</argument>
<description>
Sets the maximum angle constraint for the joint at [code]joint_idx[/code].
</description>
</method>
<method name="set_ccdik_joint_constraint_angle_min">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="angle_min" type="float">
</argument>
<description>
Sets the minimum angle constraint for the joint at [code]joint_idx[/code].
</description>
</method>
<method name="set_ccdik_joint_enable_constraint">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="enable_constraint" type="bool">
</argument>
<description>
Determines whether angle constraints on the CCDIK joint at [code]joint_idx[/code] are enabled. When [code]true[/code], constraints will be enabled and taken into account when solving.
</description>
</method>
<method name="set_ccdik_joint_rotate_from_joint">
<return type="void">
</return>
<argument index="0" name="joint_idx" type="int">
</argument>
<argument index="1" name="rotate_from_joint" type="bool">
</argument>
<description>
Sets whether the joint at [code]joint_idx[/code] is set to rotate from the joint, [code]true[/code], or to rotate from the tip, [code]false[/code].
</description>
</method>
</methods>
<members>
<member name="ccdik_data_chain_length" type="int" setter="set_ccdik_data_chain_length" getter="get_ccdik_data_chain_length" default="0">
The amount of CCDIK joints in the CCDIK modification.
</member>
<member name="target_nodepath" type="NodePath" setter="set_target_node" getter="get_target_node" default="NodePath(&quot;&quot;)">
The NodePath to the node that is the target for the CCDIK modification. This node is what the CCDIK chain will attempt to rotate the bone chain to.
</member>
<member name="tip_nodepath" type="NodePath" setter="set_tip_node" getter="get_tip_node" default="NodePath(&quot;&quot;)">
The end position of the CCDIK chain. Typically, this should be a child of a [Bone2D] node attached to the final [Bone2D] in the CCDIK chain.
</member>
</members>
<constants>
</constants>
</class>