Content Dev:CC Clothing Physics
Contents
- 1 Application and Coverage
- 2 Single-Sided Mesh Requirement
- 3 Integrated Accessories and Thickness Constraints
- 4 Mesh Finalization: Triangulation and Normals (Maya)
- 5 Polycount Allocation Dynamics in Soft Cloth Physics
- 6 Reference Examples for Density Distribution
- 7 Topology and Structure Specifications
- 8 Soft Cloth Physics Setup & Preview Guide
- Main article: CC Asset Development.
Application and Coverage
- Physics Threshold: For long-line garments that extend from the waist to below the glutes (hips), the Soft Cloth physics attribute must be assigned to the lower section of the garment (hemline region).
- Structural Limitations: Any mesh region designated for Soft Cloth physics is not suitable for modeled thickness or volumetric structures (e.g., closed cylindrical meshes).
Single-Sided Mesh Requirement
- Topology Standard: For all areas requiring Soft Cloth simulation, the mesh should be constructed as a single-sided surface. To maintain visual visibility from both sides, enable the 2-Sided (Double-Sided) shader option in the material settings.
- Case Study – Robe/Gown
- Sleeves: If sleeves require Soft Cloth physics, do not add thickness to the cuffs.
- Front Placket / Opening: If the upper torso remains static while the lower section requires movement, geometry should transition from a volumetric structure at the upper region to a single-sided surface in the Soft Cloth physics region. This transition should occur gradually around the crotch area to ensure stable deformation and natural draping.
Integrated Accessories and Thickness Constraints
For garments designated for Soft Cloth simulation, the following geometric rules must be followed to ensure stable behavior:
- Accessory Integration: All rigid accessories attached to the garment (e.g., buttons, zippers, buckles) must be merged into a single contiguous mesh with the main clothing body.
- Alternative Workflow: If geometric merging is not feasible, these details should be represented using Normal Maps rather than physical geometry.
- Thickness Limitations: For garment openings within the Soft Cloth physics region (e.g., hemlines, cuffs), physical thickness should not be modeled. These areas must remain single-sided surfaces without internal faces.
- Simulation Stability: Failure to follow these rules may result in accessory detachment or mesh separation during Soft Cloth simulation, leading to visible artifacts.
Mesh Finalization: Triangulation and Normals (Maya)
Before final export, ensure mesh topology and shading data are properly validated using standard Maya procedures.
Uniform Triangulation Flow
- Procedure: After completing the mesh, inspect topology flow and use Maya’s Triangulate tool to enforce consistent face orientation across all polygons.
- Purpose: This helps prevent sawtooth artifacts and uneven shading during deformation or simulation.
Normal Direction Correction
- Procedure: Verify that all vertex and face normals are consistently oriented outward.
- Execution: Use Mesh Display > Conform in Maya to unify normal directions and correct any inverted faces (backfaces), which may cause shading issues in downstream engines.
Polycount Allocation Dynamics in Soft Cloth Physics
The strategic allocation of polygon density significantly influences Soft Cloth physics behavior. A balanced distribution should be determined based on the desired material response and visual outcome.
- Excessive Polycount: An overly dense mesh can cause fabric behavior to become excessively soft, reducing structural definition.
- Insufficient Polycount: A low-density mesh can result in overly rigid behavior and may produce visible faceting or angular deformation during motion.
- Optimization Guideline: Polygon density should be allocated according to the specific requirements of each garment. Due to variations in garment length, silhouette, and material response, a universal polycount standard is not recommended.
The following examples provide reference strategies for density distribution.
Reference Examples for Density Distribution
Style A – Long Coat (Structured / Stiff Fabric)
For garments intended to maintain a structured appearance, a relatively lower and uniform polygon density is sufficient to preserve form while maintaining stable Soft Cloth physics behavior.
Style B – Knee-length Dress (Flowing / Soft Fabric)
To achieve a soft, dynamic flowing effect, higher polygon density should be concentrated in regions influenced by Soft Cloth physics (typically the skirt area). The bodice or torso region, which remains static, can use lower density to improve performance and efficiency.
Topology and Structure Specifications
Mesh Distribution and Flow
- Uniform Density: Ensure polygon density is evenly distributed across the mesh surface. Avoid abrupt transitions between high-density and low-density regions unless required for specific behavior.
- Grid-like Topology: Maintain a clean quad-based edge flow with a consistent grid-like structure. Polygon shapes and sizes should remain as uniform as possible across the mesh.
- Topology Consistency: Avoid irregular edge flow, uneven polygon distribution, excessive poles, or significant differences in polygon size between adjacent regions, as these may negatively impact Soft Cloth physics stability and deformation quality.
Robe Construction for Soft Cloth Physics
- Single-Sided Transition: When creating robe-style garments, the lower hemline is typically designated for Soft Cloth physics. Geometry below the crotch area should transition into a single-sided surface, removing any modeled thickness within the Soft Cloth physics region to ensure stable deformation and natural draping.
Soft Cloth Physics Setup & Preview Guide
Official Documentation
For detailed information on cloth physics parameters and system behavior, refer to the official Reallusion documentation:
Instructions
1) Enable Global Simulation
By default, physics simulation is disabled. To preview cloth behavior, enable the following controls from the main toolbar:
- Rigid Body Simulation
- Soft Cloth physics
2) Activate Object Physics
To enable Soft Cloth physics for a garment:
- Select the target clothing object.
- Open the Modify Panel.
- Navigate to the PhysX tab.
- Enable Activate Physics.
Once activated, the garment will participate in Soft Cloth simulation and can be previewed in real time.
3) Load Weight Map
Click the Weight Map button to open the Edit Weight Map Panel.
Import a prepared grayscale weight map to define vertex influence values for Soft Cloth physics. This controls how different regions of the mesh respond to simulation forces, enabling fine-grained deformation control.
4) Parameter Tuning
Use presets to quickly apply standard fabric behaviors, or manually adjust parameters in the Property section to refine simulation results.
