A First Look At KineFX

as a version 18.5 houdini has a new raging system called kinefx it is a massive improvement over the old system and brings improvements to animation retargeting and animation blending in this video we'll look at the most basic elements of rigging the first will be deformers these are usually referred to as bones but in kidney fx it is better to think of them as joints the second would be adding controls to the rig the controls will be needed for animators to use the rig more easily in this video i'll look at the most basic fk setup the final aspect of rigging is deformation this is where we'll drive the mesh with the joint transformations kidney fx moves the rigging into sops which means the entire rigging system is now in the same context previously we'd have a bone and this bone would have two components the first is the capture region which is used for deformation the second bone is the bone link node this can also be used for deformation but is primarily used for the display of the bone geometry we no longer need these anymore but we will still encounter references to them when performing deformations and kidney effects in kidney effects we'll use points for again however we will refer to them as joints these joints are essentially just transformations and all we really need for again is a transformation and a hierarchy kidney effects will allow us to make a regard of any points but i will not explore that in this video we will instead start with a very basic tool for building rigs and this node will be found under kinefx and is called skeleton this node will give us a workflow that is similar to the traditional rigging workflow press enter in the viewport with node selected and the options on the top of the viewport will allow you to control the node and they're the following name is where we can name the joint child compensation will allow you to move the points independently of the hierarchy we then have two editing modes create and modify scale inheritance will control how the child joins inherits scaling and joint placement will allow you to control how the joints are made the tweak node is used for joint manipulation the snap tools all work with this node i'll turn on step to grid and then draw the bones and i'll press enter to finish i select the first point and i rename it to root i can also set this point's color the next point will be called middle and i can set the color as well the final point will be the effector so now i have three joints the are the middle and the root if i want to view the hierarchy i can go to the new pane tab and then i can go to animation and open reg tree and here we can see the parenting structure i've created the bones and now we'll need to manipulate them the bones can be positioned with the rig pose node when selecting this node i can press enter in the viewport and i can rotate my joints the transformation will then be registered within these nodes these transforms are relative to the original position of the points there are also quite a few ways to visualize the rig the most straightforward is the visualize rig node if we select this node it will show the transforms this node also inherits the point color if we turn on show parent to child we can see the hierarchy relationship most importantly we have a representation of coordinate space there are tools to change the coordinate space but they're not applicable to this video the most important thing with coordinated spaces is to keep them consistent we can then take a look at how these coordinates are presented on the points themselves in the geometry spreadsheet the first attributes are the point positions these will be used for translation of the joints since the points are already giving us the world translation the word transform is actually separated into a rotation matrix and a translation vector in kinefx with the translation vector being the point position we then have the colour attributes for the point color then there will be 16 attributes for the local transform this will start with local transform 0 and end with local transform 15 and this is a 4x4 matrix the local transforms are not the most important part of kenny effects as kenny fx tends to be more reliant on the world transforms next we have the joint names these are very important as most of the rig will be organized off point names we then have the point scale inheritance and finally we have the transform this matrix is a nine by nine matrix and it stores the world rotation so now i have a skeleton and we compose it using the rigged pose note but what we have is not really accessible to an animator who does not understand rigging so instead of selecting the points and dealing with him directly we want to create controls for the rig and attaching controls to the joints is actually very simple and we're going to do it with a attach control geometry node the attach control geometry node will copy geometry to the points we can use any geometry as this is a basic example i'll start with a box we can also use a control node and in this case i'll just set this to a sphere these nodes will need to have a name attribute i'll add this with the name node and i'll name the box box and the control will be named sphere i can then merge these notes and these will be connected to the attach control geometry node i'll then add some controls to the attached control geometry node first i'll select the joint the control will be connected to the joint will be specified using the name attribute i can then use the controls name to specify the control the controls now match the joints transforms we can modify the controls transforms but this transform will happen in the joint space so this movement will happen in the local space of the joint if i want to move the control in the joint y axis i'll need to move the control in the control's y axis we can also copy a single control to multiple points if i select the middle joint and the effector i can then use the sphere control for both joints now i can use the rig pose node and it'll give me far more accessible controls that is the basic system for attaching controls it is a very simple system but it is very flexible especially when we start to use constraints with either vex or vox next we'll work on the defamation deformation is not particularly difficult and bringing the rig into the sub's context makes the process a lot more elegant we will begin by getting the bone capture lines node this node is used to specify which bones are in the rake if we plug in our skeleton we'll find that the bones are being defined by the points this is done using the name attribute if the point displays on it will show how the bones are being captured we can alter how this works using the sample segments option but i will tend to leave this as default i'll then turn off capture pose as we are no longer using the capture node that comes in the object space bone the same applies to bone link now that we have defined the bones i'll use the tet embed node this node used to be called solid in bed 2.0 this node will create a tetrahedral mesh around our geometry and this mesh is used to determine the point weights we can turn off enlarged input mesh we want our tetrahedral mesh to conform to our original geometry the next node that we want is bone capture bioharmonic the first port will be connected to our original mesh the second port will be connected to the tetrahedral mesh this node will calculate the weights for the deformation and transfer them to the original mesh next we'll add a stash node i can store the weights in this node rather than constantly having to update them to store it i'll click on the stash input button finally we can apply the deformation this will be done using the bone deform node the first input of the bone deform node will be connected to the stash node we now have a deformation but it is not correct to conform this deformation to actual rig i'll connect the pose control to the final input the middle input is used for the rest pose in this case i'll just plug in my original skeleton then in order to make my deformation easier to modify i'll add a capture layer paint node this will allow us to use the paint tools to edit the weights on our mesh in order to see the bones i can plug the pose rig node into the final input of this node and now we would appear to have a completed rig but we actually have a problem if we look at the painted weights we'll see we have another white color at the bottom of the last bone to illustrate the problem i'll select the capture node we can select the capture regions and we have three regions here the root the middle and the effector i do not need weights for the effector but i can select it and paint weights on the rig the reason for this is that every joint name will be read as an individual capsule region in order to fix this i'll need to rename the effector to have the same name as the joint that precedes it in this case it will be the middle in order to fix this i'll use a name node the method i'm using is a brute force method when actually creating a rig i'd prefer to use something more procedural in this case i'll manually specify the final point which will be 2. this node will need to be set to points i'll then change the name to be middle i'll then need to update my stash node i'll also want to update my scene my points for the deformers are now named root middle and middle the weights are painted for the effector have now all been removed from the mesh leaving zero values and i can now repaint the values for the middle deformer although in this case it is easy to replace the capture layer paint node that's the basics of what you need to know to work with guinea fx we'll then ramp up complexity either with solver nodes or with vex and bob's constraints we can also make the controls more accessible by connecting them to an hdi you

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Id: 9f06tjunxUs

Length: 12min 25sec (745 seconds)

Published: Wed Nov 04 2020