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Skeleton Builder

The Skeleton Builder is designed to speed up skeleton creation and joint placement process, while still being fully transparent and easy to tinker and edit.

Purpose

  • Quickly generate a clean skeleton with consistent naming and orientation.
  • Use guide locators to position joints non-destructively.
  • Optionally preview the IK bend direction before building.

Step 1: Choose a preset

In the BroRig window, under Skeleton Builder:

  • Select a preset (e.g., biped).

Available presets: - Biped (UE Mannequin): Root, spine, arms, legs using UE naming. - Finger (single): For finger chains, ensures proper joint orientation and making sure the finger chain is straight.

Step 2: Spawn guides

Click Spawn Guides: - A hierarchy of colored locators is created under Skeleton_Guide_GRP. - Guide markers: - L/R locators: Define the side spread. - Up locators: Define the bend direction (e.g., knee cap direction). - Pos locators: Direct placement for spine, non-hinge joints, etc. - *_end locators: End targets for final orientation (e.g., head_end, ball_l_end).

Step 3: Place the guides

  • Move, rotate, and scale guides to match your character’s proportions.
  • For limbs:
  • Place the L/R markers around where the hinge should bend.
  • Move the Up marker in the direction the joint should bend (e.g., toward the knee).
  • A translucent triangle mesh will preview the IK plane for hinge joints (e.g., elbows, knees).

Guidelines: - Keep the root at your character’s base. - Ensure the spine is vertical and limbs are in a neutral pose.

Step 4: Build skeleton

When guides look correct:

  • Click Build Skeleton.
  • The tool:
  • Projects hinge joints onto a clean plane (based on L/R and Up).
  • Creates and orients the joints.
  • Mirrors the left side to the right side automatically.

The resulting joints use UE-style names (e.g., upperarm_l, calf_r), ready for BroRig modules.

Step 5: Clean up

  • After you are satisfied, click Delete Guides.
  • Your skeleton is now ready to use for:
  • Installing BroRig modules.
  • Skin binding and animation.

Twist joints

For realistic twist deformation (e.g., forearm, upper arm, thigh, calf):

  • With two adjacent joints selected, use:
  • Rigging Tools → BroRig → Add Twist Joint
  • This creates a properly named twist joint (e.g., upperarm_twist_01_l).

Then you can use the Twist module to wire twist controls into the rig.