Using Maya, create a barstool made of nine separate polygon cylinders: one seat, four legs and four leg braces.

In order to have each piece of the barstool break apart in endorphin (and eventually back in our 3D software), you have to create a simple joint hierarchy for the barstool. In Maya, open the "Skeleton > Joint Tool" and set "Orientation" to "None" so each created joint’s orientation matches the World Axis (this is very important!).

To make the legs of the barstool, draw a bone from the top to the bottom of the leg. Do the same for the leg braces in a horizontal manner. Create your seat by creating another small bone using one joint located in the middle of the seat and another just above it. At this point, you’ll have nine separate "bones" (two joints each) for each of the barstool model parts. Finally, add one root joint just underneath the barstool’s seat and parent the leg/brace/seat bones underneath it. Save this file, naming it something like "barstool_001." We will parent the barstool geometry under the joints later. The Maya Outliner of the joint hierarchy is shown here.

Select all the barstool polygon geometry and export it as an "OBJ," naming the file "barstool_ref.obj" (you will need to have the "objExport.mll" plug-in loaded before you do this in Maya), then delete the barstool geometry from your scene. Then, select the root joint of the barstool skeleton hierarchy and export it to an FBX (you will need to have the "fbxmaya.mll" plug-in loaded before you do this in Maya). Name the file "barstool_joints.fbx" and use the default settings in the FBX export popup window and hit the export button.

In endorphin, go to "File>Character Edit Mode>New Character." In the New Character dialog window, uncheck "Create Character Using:" and check "Create Reference Character Using:" then hit the "…" (browse) button and locate the "barstool_joints.fbx" FBX file. In the FBX import options window, click on "Root Node" and then click OK.

You should see the barstool joints represented by gray capsule-shaped "mass" objects. Imported joints will have mass objects created on them by default (as long as they have a child joint). There are also blue collision objects here but they are obscured by the mass objects. You can right-mouse-click in the viewport to toggle the display of mass and collision objects. Next, import the "barstool_ref.obj" OBJ file, which will be displayed as partially transparent geometry; this will serve as a guide for adjusting the mass (gray) and collision (blue) objects.

In endorphin, go to "Window>Node View" to display the scene hierarchy. Expand the barstool character in the Node View by hitting the "+" symbol. Select the barstool root joint, and in the Property Editor set the "Geometry Type" for the mass object to "Cylinder" and position it to the middle the seat of the barstool. The root joint’s collision object won’t be used here so you can delete it.

Next, set the geometry types for all the legs and brace mass and collision objects to "Cylinder." Resize the mass/collision cylinders using the "Radius" and "Length" attributes of your collision objects to more closely represent the OBJ reference model. Make certain that none of the collision objects intersect, otherwise you will get collision objects jumping oddly during simulation. You can also use the translate, rotate and scale tools in endorphin to adjust the mass/collision cylinders as well.

For each of the barstool leg and brace collision objects, select one at a time and check on the "Collides With Parent," "Collides With Siblings" and "Collides With Ancestors" checkboxes in the Property Editor. This will ensure that the barstool parts inter-collide correctly.

For each of the leg and brace joints, select the joint and set its "Locking" attribute to "CoordsAll" in the Property Editor to ensure the rotations are locked in place. If you do not lock these joints, the barstool will look like a wind chime when simulated! But don’t do this for the root joint.

Save this endorphin barstool Character using "File>Character Edit Mode>Save Character" and give it a name like "barstoolProp_001."

In endorphin, go to "File>New Scene…" and then add your barstool to the scene through the "Character>Add Character…" menu by selecting "barstoolProp_001." Select the barstool character in the Timeline and translate it slightly behind the default character in the scene.

To break apart the barstool, go to any frame on the barstool’s timeline and right mouse click-select "Create Sever Event." Add parts of the barstool to the "Sever Event" by selecting the sever event in the timeline, then in the Property Editor click on "[Select]" then shift-select the "mass" objects of the barstool.

In this example, I used a "force" to push a character into the barstool. The sever event was added at frame 39 so it breaks apart as the character crashes into it. Add as many barstools as you want to the scene by using the "Add Character" menu. You may also want to check on endorphin’s Simulation Setting "Non-Spherical Mass Objects" for more convincing dynamic motion from the barstool parts. In addition, you can edit any of the mass objects’ "density" attributes to make the barstool pieces heavier or lighter (you can do this in "Character Edit" mode).

In Maya, open the "barstool_001" file you saved earlier and parent all of the barstool seat, legs and leg braces under their appropriate joints.

Next, go to "File > Import" and find the FBX barstool animation file you saved in Step 5. In the FBX dialog window click on "Merge," verify the frame rate and then press the "Import" button. The animation should be imported onto your barstool.

If the animation looks "jumpy" or "poppy," you may want to run the "Euler Filter" and the "Resample "Curve" tools in Maya to improve the motion quality and resolve any motion blur issues.

You may be saying to yourself, "Hey, I could’ve done this using my 3D software’s dynamics engine." You’re right, but I can assure you, in complex scenes with many interacting characters and props, nothing beats endorphin.

Once you’ve finished animating, you’ll need to export the animation from endorphin to your 3D software. Select the barstool character in the endorphin timeline and then go to "File>Export…" using the Alias FBX 6.0 file format and setting the "Frame Rate" appropriately for your project.

Tim Coleman
Character Rigging Supervisor
Giant Killer Robots
San Francisco, CA

Tim Coleman has 12 years of 3D production experience in architectural, video game, commercial and feature film work. Tim has worked as a character technical director at Tippett Studio, ESC Entertainment and currently at Giant Killer Robots. He is also co-creator of "Bowlin’ Fer Souls," an award winning animated short seen in "Spike and Mike’s Animation Festival."

Tim Says Keep In Mind…

NaturalMotion’s endorphin is already highly touted for its ability to create dynamic human body motion. We used endorphin in a recent production and it proved to be a powerful tool for creating complex prop animation. This tutorial shows you how to use endorphin to create a breakable "barstool," like you’d see in a bar room fight in your favorite spaghetti western. We used version 2.5’s incredibly fast rigid body solver and "sever" events, as well as Autodesk Maya 7. But this technique is just the tip of the iceberg of what you can do with endorphin’s extensive 3D animation toolset. The software ships with several helpful tutorials; For instance, check out "Tutorial 6: Creating Props." And because NaturalMotion offers a free Learning Edition and an informative online forum, you can experiment with the software and learn from other endorphin users before investing in the product.

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