Houdini 21.0 Nodes Geometry nodes

Muscle Deform geometry node

Deforms muscles based on rest and target bone geometry using a fast, quasi-static solve for realistic volume-preserving motion.

Since 21.0

This node applies muscle deformation based on animated bones, producing volume-preserving muscle motion. It uses a quasi-static solver that evaluates each frame independently—no simulation history is required. You can tune fiber stiffness, end constraints, and muscle tension to achieve the desired deformation.

Parameters

Group

The subset of geometry to process.

Quasi-Static Solve

Quasi-Static Solve

Enables the quasi-static solver. When on, each frame is solved independently without relying on previous-frame states.

Iterations

Number of solver iterations per frame. Higher values will improve convergence, particularly for stiffer settings, but will increase computation time.

Fiber Stiffness

Controls how strongly muscle tension affects muscle geometry.

Muscle End Stiffness

Controls how rigidly the muscle’s ends are anchored to their attachment points. Higher values keep muscle ends more locked in place.

Tension

Automatic Tension

When enabled, tension is automatically computed based on muscle length changes relative to rest length.

Muscle Base Tension

Sets a constant baseline tension applied to the muscle, regardless of length changes.

Muscle Base Tension Mode

No Scaling

Uses the same base tension for all muscles in the group.

Scale by Attribute

Multiplies the base tension by a per-point attribute for fine control over individual muscles.

Muscle Base Tension Attribute

Name of the point attribute used to scale base tension when “Scale by Attribute” is selected.

Muscle Tension

Sets the amount of active tension applied to the muscle, simulating contraction forces. This can be animated to drive muscle flexing.

Muscle Tension Mode

No Scaling

Uses the same active tension for all muscles in the group.

Scale by Attribute

Multiplies the active tension by a per-muscle attribute, typically muscletension.

Muscle Tension Attribute

Name of the attribute used to scale tension per muscle when “Scale by Attribute” is selected.

See also

Geometry nodes