Creating a Double IK Chain in Lightwave By: Jake Stewart, Stewart864@live.missouristate.edu Introduction: This tutorial is provide some helpful (hopefully) instructions on creating a double IK chain in Lightwave. Here we will be using both programs the Lightwave package, Modeler and Layout. This should be helpful in creating characters that may have tentacles/tendrils, long tails, or whatever elongated, bendy form you choose to create. Step 1: Open up modeler. Under the create Tab, select your Disc tool. Doesn t matter which window or view you want to work in, just make sure you re making a long disc shape Step 2: Once you have the disk stretched out to an appropriate length, you are going to need to change the segments it has. For the sake of this tutorial, I m going to go ahead and use 13 segments. The segments can be changed with your arrow keys while still creating your disc or by pressing the N key to go to the numeric menu, and changing it there. Step 3: Now that we have a nice cylinder, we are going to want to go ahead and color code it by surfaces. We re going to start by selecting all the polygons and changing our surface to tendril. Let s make it a nice shade of red. Color coding it will help later steps be a bit easier when we add the bones. Step 4: For the sake of the tutorial, I will be referring to segments by numbers, starting from the bottom. We want to grab segment 1 from our cylinder and re-label it another surface. Let s call it Base and make it green.
This will become more important when we start adding our bone structure. Step 5: Now for the next step, we re going to change one more surface. Select segment 7 and change that one to Middle and color it blue. Step 6: Make sure all surfaces are set to smoothing in the surface editor. With surfaces out of the way for easier reference points, it s time to do weight maps. These are especially important when messing with bone structures. Select the green Base/ segment 1. Head to the bottom right corner by the W on screen, then hit the tab. When the pop-up asks for a new weight map, name it Base and hit create. You can see your new weight map by pressing the tab by any of your viewports and changing it to weight Shade. Step 7: Now select all segments between green and blue, including blue (segments 2-7). Create a weight map for them called Tendril_1. Should look something like the picture if done correctly in weight shade view. Step 8: Final weight shade coming up. For this one, we want to select all segments from blue and then up (7-13). Name the weigh map Tendril_2. Step 9: It s time to move on to Layout. Save this project as Tendril to the desktop so it s easy to find. Now send the open to layout/open it up in there. To make things easier to work, go ahead and hit the D
key to bring up the Display tab in the Preferences menu. From there, hit Viewport Layout from the top of the tab and change it to Quad. Step 10: Before we start adding the bone structure, go ahead and toggle Bone X-Ray on under each viewport. It will be under the 3 rd dropdown tab by your viewing options. Step 11: Time to really start getting that skeleton together. Under the Setup tab, select Bone. Name it Base, and have the end right before segment 2/ the red area. You can change the size of the bone by hitting the P key while the bone is selected, and adjusting the rest length. Step 12: Go ahead and add a child bone to Base by hitting the = key. Name it tendril, and make sure it ends halfway through the next segment (consult picture for help). Do this until you get all the way to the end of the cylinder, adding one extra not inside it. Name that last one tendril_end for reference later. (Step 12 picture next page)
Step 13: Now go on back to the bone that should be labeled tendril (5) located in the first half of the blue section/ segment 7. Add a child bone to that and label in tendril_dummy. Place it within the blue still, next to tendril bones 5 and 6. The dummy bone here and the tendril_end bones will be used for null objects, helping us achieve that slick, S-shaped bendy articulation. Step 14: Now that you re looking real good with those bones, we re almost at the point to make them start dancing. Head on down to Base Go ahead and hit the M key for Motion Options. Under the IK and Modifiers tab, make sure to check of the Unaffected IK of Descendants box. Step 15: Click on the Controllers and Limits tab. Under there, head for yet another tab labeled as Rotation. Go ahead and change the Heading, Pitch, and Bank controllers to Inverse Kinematics in the drop down.
Step 16: Hope you like menu navigation. For the next step, you are going to want to go to the motion options by way of the M Key for tendril (1) all the way to tendril_12 and tendril_end. While there, you ll need to change all of the Heading and Pitch settings to Inverse Kinematics under the rotation tab. Step 17: Go back to the bone Tendril (6) in the blue. Head to the motion options, and change that bone to be Unaffected by IK of Descendants in the IK and Modifiers tab. Step 18: Time to create some null objects for our cylinder to behave by. Under the Items tab, head to Add Null. Name it Mid, and hit the edit tab. Change the shape to ball, the label as Mid, and the selected and unselected colors to whatever your heart desires. For the tutorial, I ll make mine blue to match the mid segment surface. Place it in the middle of the cylinder, right on the blue segment by the dummy bone.
Step 19: Add another null, this time changing the labels to End. Might I suggest red for the color? Place it right by the bone tendril_end in a similar fashion to the previous Null. These nulls do not show up in rendering, and will be used in controlling the motions of our cylinder/ tendril. Step 20: Now that we ve got our nulls, we need to have bones assigned to them. Go ahead and grab tendril_end. Hit the m key to bring up motion options. Under IK and Modifiers, set End as the goal object. Also make sure under objective, you select Go to Goal. You will also need to check off Match Goal Orientation, Keep Goal in Reach, and Full-time IK. (Hint, you may need to remove Match goal Orientation at the end if it breaks. Sometimes Lightwave is like that, plus the cylinder object end is different from a typical tendril end-shape.) Step 21: Now go back to Tendril_dummy and open its motion options as well. Set its goal object to Mid, as well as the objective to Go to Goal." You ll only need to check off Full time IK. At this point move the bones and see if they are flexible. We re almost done, and we d hate to activate them if there s a problem. Also, don t be afraid is the structure bends a bit out of place as you place these settings. You can bend it back into shape before activating the tendril/cylinder. Step 22: Before that sucker gets to dance, we need to set the weight maps. Head to the bone Base and hit the P key for properties. Hit the tab next to bone Weight Map and select Base. Step 23: Repeat this process for tendril bones 1-5 and the dummy bone, but instead of selecting Base select Tendril_1 as your bone weight map.
Step 24: Repeat step 23 for bones 6-12 and the end bone, making your bone weight map Tendril_2. Step 25: The time has come to activate it. Start at the bone Base and press R or Bone active in the properties menu. It is very important the bones are activated in order. It s easiest to just hit the down key after you activate each bone to stay in order. Step 26: By now, your cylinder/tendril should be wiggling just the way you d want it to. If it looks a bit rough, that s alright, the technique works much smoother on sub patched objects. Also, you may want to add more sections and cuts in the mesh, depending on what you re going for in your final project. However, you now have the knowledge to create and more accurately animate writhing snakes, squid arms and whatever you can think up. Imagine what you can do with even more IK chains. Character Example of Numerous IK Chains: