How to Create Jiggle Physics in Blender with Soft Bodies

Creating realistic jiggle physics in Blender relies on the Soft Body simulation engine, which calculates dynamic spring-like deformations across a 3D mesh. This guide covers how to prepare your mesh topology, configure the Soft Body modifier, use vertex groups for pinning, and fine-tune spring and damping settings to achieve believable secondary motion for organic models, gelatinous objects, and character animations.

1. Prepare the Mesh Topology

A successful soft body simulation requires clean, evenly distributed topology. Triangles or uneven quads can cause irregular stretching and simulation artifacts.

• Select your object in Object Mode and press Tab to enter Edit Mode.
• Ensure the mesh has sufficient density. If necessary, add a Subdivision Surface modifier and apply it, or right-click and choose Subdivide to add uniform geometry.
• Keep the resolution balanced; overly dense meshes significantly increase simulation calculation times.

2. Set Up a Vertex Group for Pinning (Optional)

If only parts of the object should jiggle (such as flesh attached to a rigid bone, or the top of a jelly attached to a plate), you must define fixed points.

• In Edit Mode, go to the Object Data Properties tab (green triangle icon).
• Under the Vertex Groups panel, click the + button to create a new group.
• Select the vertices you want to remain stiff or anchored.
• Set the Weight slider to 1.0 (fully anchored) or lower values (partially flexible) and click Assign.

3. Enable the Soft Body Modifier

• Select your object and navigate to the Physics Properties tab.
• Click Soft Body.
• In the Soft Body panel, locate the Object settings:
  • Mass: Determines the weight of individual vertices. For light, bouncy objects, keep this low (e.g., 0.2 to 1.0 kg).

4. Configure Goal Settings

The Goal setting determines how strongly vertices attempt to retain their original animated or rest positions.

• If using the vertex group created in Step 2, check the Goal box.
• Under the Goal sub-panel, set the Vertex Group to your newly created group.
• Adjust the stiffness:
  • Default / Min: Lower values (e.g., 0.0 to 0.2) allow more free-flowing jiggle.
  • Max: Sets the maximum rigidity for weighted vertices.
  • Damping: Controls how quickly the motion settles. A value between 5.0 and 10.0 prevents endless oscillating.

5. Tune Edges and Springs for Realistic Bounce

The Edges panel acts as internal structural springs holding the mesh together.

• Check the Edges box.
• Pull & Push: Control resistance to stretching (Pull) and compression (Push). For realistic jiggle, set both to moderate values (between 0.5 and 0.9). Lower values result in gooey or rubbery results; higher values create stiffer motion.
• Damp: Prevents the mesh from vibrating uncontrollably. Set between 2.0 and 10.0.
• Bending: Crucial for organic volume retention. Set between 0.5 and 2.0 to prevent the mesh from collapsing in on itself.
• Plastic: Keep at 0 unless you want the deformation to become permanent over time.

6. Add Collisions and Cache the Simulation

• To make your soft body interact with its environment, select any obstacle objects, go to the Physics Properties tab, and enable Collision.
• Select your soft body object and scroll down to the Cache section in the Soft Body properties.
• Set your desired Start and End frame range.
• Click Bake to compute and lock in the simulation data.

7. Final Polish

• If the simulation jitters, increase the Min/Max Step values under the Soft Body Solver panel (e.g., Min: 10, Max: 100).
• Add a Smooth by Angle modifier or enable Shade Auto Smooth to keep the surface rendering cleanly.
• Add a Subdivision Surface modifier below the Soft Body modifier in the Modifier stack to smooth out the final deformed geometry without slowing down the physics solver.