Working on IK documentation...

Docs/Doxyfile.in

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Docs/Reference.dox

@@ -2127,6 +2127,88 @@ CrowdAgents' handle navigation areas differently. The CrowdManager can contains
 
 See the 39_CrowdNavigation sample application for an example on how to use CrowdAgents and the CrowdManager.
 
+
+\page IK Inverse Kinematics
+
+\section Overview
+
+IK  (Inverse  kinematics  can  be  useful  in  many  situations  ranging  from
+procedural animation to small adjustments of animation. Simply put, IK is used
+when you want to position the tips of  a  hierarchichal  structure  at a known
+location and need to calculate all  of  the  rotations of the parent joints to
+achieve this.
+
+Examples include: Moving a hand to pick  up  an object, or adjusting a foot so
+it's  always  touching  the  ground, regardless of incline, or even  precisely
+ligning  up  a  large  tentacle  in  order   to   penetrate...   Never   mind.
+
+\image html ik_foot_demo.gif
+
+\section Terminology
+
+It  is  good to know some of the terminology used when talking  about  inverse
+kinematics, so you can better understand what's being said.
+
+\image html ik_terminology.png
+
+  - The upper-most node in a solver's tree is known as the \a base \a node or \a root \a node.
+  - Nodes which need to be moved to a specific target location (example: The hand of a human) are called an \a end \a effector.
+  - Joints at which multiple children branch off from are called a \a sub-base \a node.
+  - IK solvers work most efficiently on single "strings" of nodes, which are referred to as \a chains.
+  - The entire structure (in the case of a human with two hands) is called a \a chain \a tree.
+
+\section End Effectors
+
+Effectors are used to set the target position and rotation of a  node. You can
+create one by attaching the IKEffector component to a node.
+
+\code{.cpp}
+Node* node = model->GetChild("Hand.R", true);
+IKEffector* effector = node->CreateComponent<IKEffector>();
+\endcode
+
+The  effector  has  a few parameters that allow you to control how it  targets
+another  object.  You  can  set  its  target  position  either  directly  with
+IKEffector::SetTargetPosition or you  can  tell  it  to  copy the position and
+rotation of  another  node in the scene with IKEffector::SetTargetNode (or, if
+you only know  the  name  of the node, IKEffector::SetTargetName. If there are
+multiple nodes  in  the scene with the same name then the first one found will
+be used).
+
+The target position and rotation are both set in global space.
+
+Another    important    parameter    is    the    \a    chain    \a    length,
+IKEffector::SetChainLength.  A  chain  length of 1 means a single  segment  or
+"bone" is affected. Arms and legs typically use a value of 2 (because you only
+want  to  solve for the arm and not the entire body). The default value is  0,
+which   means  all  nodes  right  down  to  the  base   node   are   affected.
+
+Effectors  have  a  \a weight parameter (use IKEffector::SetWeight) indicating
+how much  influence  it has on the tree to be solved. You can make use of this
+to smoothly transition in and out of IK solutions. This will  be  required for
+when  your  character  begins picking up an object and you  want  to  smoothly
+switch from animation to IK.
+
+\code{.cpp}
+effector->SetWeight(SomeSplineFunction());
+\endcode
+
+\image ik_effector_weight.gif
+
+If you've played around with the weight parameter, you may  have  noticed that
+it causes a \a linear interpolation of the target  position. This can look bad
+on  organic  creatures,  especially when the solved tree is far apart from the
+original tree.  You  might consider enabling \a nlerp, which causes the weight
+to rotate around the next sub-base  joint.  This  feature  can be enabled with
+IKEffector::EnableWeightedNlerp.
+
+
+
+If    required,   you   can   also    set    the    target    rotation    with
+IKEffector::SetTargetRotation.  Note that this is disabled by default (more on
+this later in the solver section).
+
+
 \page UI User interface
 
 Urho3D implements a simple, hierarchical user interface system based on rectangular elements. The elements provided are:

Docs/Urho3D.dox

@@ -34,6 +34,7 @@ For further reference, see:
 \ref Audio "Audio" <br>
 \ref Physics "Physics" <br>
 \ref Navigation "Navigation" <br>
+\ref IK "Inverse Kinematics" <br>
 \ref UI "User interface" <br>
 \ref Urho2D "Urho2D" <br>
 \ref Serialization "Serialization" <br>