Intro: Rig and Animate a Rigid Body Creature
This instructable steps through the basic setup of a character or creature made of solid rigid bodies attached to a skeletal structure to be used in animation.
In this case I am working with Tinkerplay, which has numerous snap together creature parts that you can assemble in the app and pose in various ways. The steps I've outlined show how to export parts out of the app and into a 3d program of your choice to play around with and bring to life.
I've also attached an .FBX file of this Dino as I've assembled it. The file has all the parts needed to assemble the dino body as well as a skeleton, weighting and a basic run animation.
Also here's the link to the anim on Sketchfab; which is supporting animations!
Step 1: Export Parts From Tinkerplay
Use the Tinkerplay interface to download the files for the Dino
They are saved out as .STL files, you will need to convert these to .OBJ format to be readable by most 3d animation software programs.
Step 2: Convert Parts to .OBJ Format
I used Meshmixer to convert the files from STL to OBJ
Step 3: Import Meshes Into Any 3D Animation Software (Maya)
Import all the meshes into the program and move them around and rotate them into position to build up your creature.
Do not scale anything, only use rotate and translate to position the parts, ensuring that the balls and sockets are used to orient the parts to each other.
Step 4: Create Animation Skeleton (rig)
- Create a joint at every ball and socket intersection location, use the center of the ball and socket holes as the location for the joint. This joint location will be the pivot point about which your part will rotate and move from.
- Build the entire skeleton this way, making sure to name each joint.
Step 5: Weight Mesh to Skeleton
- Weight each part entirely to a single joint, all vertices of that part should be weighted to a single joint.
- You can alternatively just parent the mesh part to that particular joint instead of using vertex weighting. Since this is a rigid body animation either will work.
Step 6: Animate!
You are ready to animate! In my .fbx example file I created a few IK (inverse kinematic)handles to move his upper torso, legs, and tail independently.
I set keys at every 6 frames of a 24 frame timeline to create a quick run cycle.