3ds Max


Maxscript: Constrain to Biped 2.0

Two years ago, I wrote a post about a maxscript I had written that constrains a humanoid rig to the 3D Studio Max’s biped. Recently, I’ve been working on a fighitng game prototype. I’m using animations from an asset package for this, and though the animations are very nice, there are sometimes things missing or I wish I could make certain tweaks. I said to myself, “I wish there was a way to record these animations so I could edit them more easily.”

I know you can import a .fbx file, the format of the aforementioned animations, into 3DS Max, but every frame is keyed and making edits is rather difficult. I could try and use animation layers, but if I want to apply the animation to a different character, this can’t really be done either.

So, remembering the script I wrote awhile ago, I figured I would try and make a version, so I could record animations. At the same time, one issue with the previous script was that when using it, it forced the original rig to rotate so it would fit the biped. This would cause this strange “bulging” in various areas that some users, including myself, didn’t care for.

Before rigging [left] / After rigging [right]

Most of this is due to the fact that not all rigs are not perfectly aligned like the biped so when going from a rig’s t-pose to the biped’s, the rotation done to conform the rig to the biped results in some rotations that otherwise, the original rig wouldn’t utilize.

The New Script

Version 2.0

This new version has a few changes compared to the original:

  • The bone selection area has been separated into two columns for easier organization
  • The addition of a lot of new features and buttons
    • Quick Midpoint – creates a new midpoint between selected objects
    • Quick Connector – creates a new bone that connects two selected objects
    • Foot Angle Adjustment in Degrees: An angle, measured in degrees, used to more correctly size the created biped’s foot
    • Turn Figure Mode Off: A toggle button that turns figure mode on and off
    • Alignment Tools and Animation Recording, both of which will be explained later

How to Use

Preparing the Rig

So, like the original version, you start off by preparing the rig. You have to add make sure that all bones (besides the infamous bone #7) are assigned properly. This can be done using tools such as quick child.

Determining Foot Angle

One new value that should be assigned is Foot Angle Adjustment in Degrees. This value is used to determine how big to make the biped’s foot and when aligning the biped’s foot to the original rig’s, how much to rotate it back so it matches the original rig’s foot angle.

One way to determine this value is to go into rotation mode and the view coordinate system and select the original rig’s foot bone.

Here, my rotation values are -12.979, -0.169, and 172.337. The biped’s foot will always be rotated positively on its z axis, so for this rig, I would use 12.979 for this value. This can be a little trial and error unfortunately, but as long as this value isn’t changed after building the biped, the toes should stay aligned properly.

Building the Biped

Once all of the bones are assigned and the rig is validated, the biped can be built. You’ll notice that when doing so a “FAUX_RIG” is created as well as the creation of a bunch of dummy objects. These dummy objects are used to align the biped to your rig.

New biped and “faux rig”
Small spheres are also added to the top of the biped’s fingers to help indicate the “top” of the fingers better.

Aligning the Faux Rig

This, unfortunately, is probably the longest part of this new process. Using the Biped Alignment section, you set the index of the bone you want to edit. Then you click one of the rotate buttons. When time this button is clicked, it’ll realign the associated bone with the newly aligned faux dummy.

How a misaligned biped MAY appear depending on the rig.

Fortunately, every time you do a rotation, it is recorded so you can save it out and reload it at a later time or for new rigs that are similarly oriented.

You can also check the alignment by clicking Align Bone or Align All. Also thighs, calves, upper arms, and fore arms do not need to be aligned since aligning the biped’s hands and feet will automatically align these better.

Another note is that you should stay in figure mode when aligning the first spine bone, the clavicles, neck, head, toes, and fingers. This is because, while in figure mode, these items are all oriented AND positioned. Once out of figure mode, they will not be moveable.

Additional Alignment Notes

If you are doing this from scratch, you should note that the clavicles are rather difficult to rotate while in figure mode. They translate to the proper position but will not align properly, but once out of figure mode, they will. Additionally, because of this, I suggest putting a slight bend in both the original rig’s elbow if possible. Even if the clavicles are off a bit, if the hands can reach the original rig’s, they and the fingers will line up properly. This is also useful to do at the knees so after positioning the hands and feet, the rig’s knees and elbows can be positions correctly. If they are too straight, these sometimes will rotate incorrectly.

Aligned rig with slightly bent knees and elbows

Finishing the Rig

Once the rig is aligned properly and figure mode is exited, you can either create constraints, which will add orientation constraints and positions constraints to the original rig so they follow the biped OR record the character’s animation to the biped.

The Key Frame button will do just that, recording the pose of the original rig to the given frame. However, you can also record the entire animation. You can set an interval. An interval of 1 means it will records every frame. An interval of 2 means it will record every other frame, 3 every third, etc.

This process, unfortunately, is rather slow. A 100 frame animation can take almost 10 minutes if every frame is captured, but once finished, the biped’s new animation can be saved to a .bip file and applied or edited.

Final Notes and Areas of Improvement

This script, though usable, could probably use some improvements.

  • Sometimes the script will crash like if you, for example, try to rotate a faux transform without building it first; thus, requiring the user to close the window and rerun the script. Having more error-catching would probably be useful.
  • I think there is a memory leak somewhere; after using the script many times or opening and closing it several times, 3ds may sometimes crash when starting a new project.
  • The alignment process takes awhile in general; I wish there was an easier way to automate this. Fortunately, I’ve created a file for Character Creator 3 rigs that should align the rig properly and quickly after being loaded.
  • Recording animation can be slow.
  • Adding rig automation would be nice so the nubs don’t need to be added manually
  • Foot sizing and placement can still be rather troublesome

Download

You can download the script here for free. If you use my script, credit would be nice but not necessary. Additionally, I would love to see what people do with it. Enjoy!


Maxscript: Constrain to Biped 8

So in 2016, I wrote a maxscript to constrain humanoid characters to 3ds Max bipeds for easier animation.  Every once and awhile, I get someone asking me for the script and some questions regarding it, so I decided to write a post about it for the future.

Here are two videos demonstrating how it works and its setup:


A quick summary:

  • What this script does:
    • Builds a biped, sizing it to fit a specified character
    • Uses Orientation Constraints to drive the original rig’s bones to the biped
  • What this script does NOT do:
    • Require new reskinning or transfer of the original rig’s skinning, which often causes issues.
    • Transfer .fbx animations — or any kinds for that matter — to the biped.  This is JUST for the rig itself.

Why?

Why write a script like this?  Well, for one I’m old-fashioned.  I’ve always liked the 3ds Max’s biped.  It’s not perfect, a little buggy; however, I’ve felt it gets the job done and has a lot of extra features — saving poses, postures, animations, etc. — that writing on my own would be rather time-consuming.  Additionally, exporting just the biped itself can be rather problematic as it sometimes moves bone objects, which causes issues with animation retargeting since that is focused more on rotation.  Since this original rig is preserved and only driven by Orientation Constraints from the biped, this is less of a problem.

Then, despite the fact other character creator tools such as Mixamo supplied rig to biped scripts, though scripts never quite worked as well as I would want, often deforming the original mesh or rig and causing unforeseen issues.

The Script

Firstly, you can download the script here.  Note, this script was written for 3ds Max 2016 but has also been tested in 2017.

Instructions

Unzip the downloaded file and run the .ms file.  You should then see the following window:

There are two columns.  The left column, Biped Bones,  is for all of the biped bones that’ll be created; the right column, Character Bones, is for the bones in the original rig.  Note, there are 2 neck bones and 3 spines in the left column; however, the 2nd neck joint and 3rd spine joint do not need to be defined and are prefaced with [IGNORE].  When this was written, it was for one specific rig that used 3 spine joints and 2 neck joints; however, since this caused issues with Unity, I decided to remove those; thus enabling it to work on more humanoid rigs.  Unity can now handle a 3rd spinal joint, but still doesn’t use a 2nd neck joint in its default, humanoid rigs.

To start populating the right column, click the row you want to define and then click the bone / node you’d like to associate with the biped bone.  It’s a bit tedious.  There are two buttons for saving and loading, Save Selection Set and Load Selection Set, respectively, that can help a bit.  If you know the names or they are named in a way that can be populated quickly through copy-and-paste, this can be done by saving a text file, updating it, and then reloading it.  In the .zip, there are two examples of these files; they are setup for use with iClone Character Creator 1 rigs.

Once the right column has been populated properly, the Validate Bones button will check to make sure the bone slots are all assigned.  This will also show a pop-up for any bones that are missing.  Warning:  This’ll generate a pop-up for every missing bone.  

If all bones have been signed, click the Build Biped button.  This will generate a biped that’ll match the size of the original rig.  You do not need to, but it is suggested to then rotate the biped as closely to the original rig.

Then, the Build Helper Rig button will create a new rig that is identical to the original rig except it’s bone orientation will match the biped’s, meaning the up, forward, and right axes will match the biped’s.  This is important for the next step.  Essentially, an early thought for this experiment was to:

  • Build a biped
  • Align the original rig to the biped

However, one of the big issues is that rigs and their bone rotations can come in a variety of orientations.  If you use 3ds Max’s default align too, arms will sometimes be rotated in strange positions.  The helper rig solves this by standing as the middleman between your original rig and the biped.  It’ll be the same size as your original rig but the bone’s will match the orientation of the biped.

Next there is the Align To Biped button.  This aligns the helper rig to the biped and then the original rig to the helper.  This is why aligning the biped to the original rig helps; otherwise the changes can look rather broken.  They are easy to fix because, again, this is just affecting rotation and not placement of the original rig.

The Create Constraint button is the final step.  All other steps should be completed first — including making backups in case there is an issue.  This will create Orientation Constraints between your original rig to the helper rig and from the helper rig to the biped.

Once this is done, the rig should now be driven by the biped.

Other Buttons & Tips

As you may note, there are two buttons I’ve yet to discuss, Quick Parent and Quick Child.  Quick Parent create a parent bone the selected bone’s parent and itself.  This would be used for something like a rig with only one spine.  This will create the second spine automatically that can be used in the rig.  Then, Quick Child, creates a joint at the end of a joint.  The biped rig requires 5 fingers as well say finger nubs, for example, and this button will create these quickly.

Another tip is that if you create a child, for something like the head nub, make sure that they are aligned perfectly vertically; otherwise, the head will be tilted when aligned to the biped.  The toes have a similar problem I haven’t quiet figured out, but again, aligning the created biped as closely to the original rig as possible will help resolve some misalignment issues.  Another tip is that instead of rotating the biped once it’s created, rotated the bones of the original rig to match the newly created biped as closely as possible.

Final Steps

After completing the steps, you can now animate just the biped as your would except you should NOT rotate the pelvis bone; this causes the hip and spine bones to translate slightly, causing issues upon export.  They will export fine, but your animations won’t match perfectly and when importing to Unity, you’ll get errors about how those bones have translation data and that said data will be ignored if it’s part of a humanoid avatar.

Also, don’t export everything; use the export selection and select only the original rig’s joints and/or any meshes you’d like to export.

Quick Summary

  • Unzip this file.
  • Run the BipedRigCreator.ms script in 3ds Max
  • Define the joints in the right column, creating children or parents where needed
  • Validate the bones
  • Build the biped
  • Build the helper rig
  • Align to the biped
  • BACKUP (if not already)
  • Create constraints

Wishlist

I’m unsure if I’ll add anything to this script anytime soon, but here is a list of things I’d like to do:

  • Streamline the bone selection or remove the left, right column idea as they aren’t lined up
  • Allow for multiple spine joints / make the correct number of spines based on the number of spine joints assigned)
  • Adjust errors for the head nub and foot nub issues
  • Not show a pop-up for every missing bone, but instead a list of all missing bones upon validation

Anyway, if you use the script, great!  I’d love to see what people do with it.  Again, I mostly wrote this so people who would like to use it in the future have something to refer to.