Choose a build, then drop a GLB mesh
and it will be measured and fitted.
Advanced settings fitting · parts · weights
Skeleton
start herePick the body your character is closest to — Humanoid then male or female, Animal, or Custom. It sets where the fit starts — shoulders against hips, waist, chest depth — and then auto-fit measures your actual mesh and maps every joint onto it. Picking the near one costs a little accuracy in the first pass, not a working rig.
Four legs. A quadruped is measured along its own spine rather than up its height, so nose-to-tail is the axis and the bands slice across the body. The legs are found standing on the floor and the hind leg is built with three segments — the joint that bends backwards is the hock, and a hock is an ankle. The true knee, the stifle, sits high and forward inside the body where the outline does not show it. The tail is not in this skeleton: it is found on your mesh and added as its own chain, so an animal without one is not given five joints buried in its rump.
There is no species to pick. Two things about an animal decide its skeleton, and both are read off the mesh itself. Posture — how high it carries the hock — is measured from the hind leg's own centre line, where the corner between the metatarsus and the tibia is the only backwards apex a leg has. Archetype — how the spine works at speed — comes from three metric tests: the foot's width against the ankle above it, the torso's length against the free front limb, and how far the shoulder blade stands clear of a dipping loin. Every number is shown with the threshold it was compared against, in Fit skeleton below.
Mesh
glb / gltfUpload the unrigged character you want skinned. Any skin data already in the file is discarded.
Fit skeleton
measuredAuto-fit puts every joint at the same place inside your mesh that it occupies inside the reference body. Then correct it by hand: drag the cyan dots on the stage, or use the sliders.
Joints are named for where they sit, not for the segment underneath them. Animation software names a bone after the part that hangs below it, so its LeftForeArm is really the elbow, LeftHand is the wrist, LeftFoot is the ankle, LeftShoulder is the collar bone, and Neck sits down on the collar bones rather than up the throat. Those names still go into the export unchanged — they are shown here in grey beside the plain one.
Press this after dragging dots on the stage. A drag moves a joint in the plane you are looking through, so it lands at the right height and the wrong depth — buried in the front or the back of the limb. This slides every joint sideways onto the middle of the bone it belongs to and pulls any stray one back inside the mesh. It also checks the spine, neck and head against the body itself and tucks back in any joint that has left it — which is what a bent or hunched back needs, since the chain is otherwise fitted as though the back were straight. Nothing moves along a limb, so the elbow, knee and wrist positions you set are kept.
Adjust the fit by hand
Pick a joint, on the stage or above, to see where on the body it belongs.
Extra parts — fingers, hair, and the rest
Extra parts
optionalThe base skeleton only covers the body the reference describes. Add parts for anything it doesn't reach. Each one is measured off your mesh, and its joints drag like any other — they show as amber dots. What's offered here follows the skeleton you chose; the custom part below builds anything else. On four legs the tail is one of these: it is added on its own whenever the mesh has one, and it holds its own weights rather than sharing them with the hindquarters.
Anything else — horns, ears, a cape, a weapon mount. It hangs off the joint you pick. There is nothing in the mesh to measure it against, so it is placed by proportion: expect to drag it.
Nothing added yet.
A measured region is a sphere and a chest is not, so treat it as a starting guess. Pick a part, then drag on the mesh to paint the area it should hold to shape. Painted vertices follow that part's nearest joint instead of the spine, which is what keeps the shape when the body moves.
Bind skin
auto weightsEvery vertex is weighted to its four nearest bones. Lower tightness spreads the influence and smooths joints; higher tightness keeps limbs crisp but can crease. Blend then averages each vertex's weights with its neighbours' across the surface, which is what stops shoulders and hips creasing along a hard line.
Weighting
Distance weighting measures straight lines through empty space, so on a mesh standing with its feet together the inner edge of one foot is nearly as close to the other foot's joints as to its own — and gets dragged after it when the legs swing apart. Keep left and right apart drops the far one of any mirrored pair of joints once it is clearly the further of the two. Anything on the midline, where the two are equally close, is left to blend as before.
A buttock sits behind the hip joint, and distance weighting has nothing to measure but straight lines — so the top of the thigh is the nearest bone to it and takes a third of it. The seat then swings with the leg and collapses. Let the pelvis carry the seat hands that share back to the pelvis above the fold at the back of the leg only, and fades it in across the fold, so the crease still folds and the front of the hip still bends.
A skull does not bend, but distance weighting gives the face a share of the neck and chest anyway, so it shears whenever the body twists or leans. This collapses everything above the jaw onto the head joint and fades the change out across the jaw line, so the neck still bends. Hair, horns, ears and other added parts keep their own hold.
Download
rigged glbWrites a clean GLB in your mesh's original units: one armature, one skinned mesh per material, ready for Blender, Unity, Unreal or three.js.