Physics

Physics Configuration

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Attributes:

• dt: (float), The time step for each physics simulation update. Defines the amount of time that passes per frame for physics calculations.
• gravity: (Tuple[float, float, float]), The gravitational force vector applied in the simulation, defined as (x, y, z) where each axis represents a directional force in meters per second squared.
• substeps: (int), The number of substeps for the physics solver. This helps with simulation accuracy, especially in high-speed or complex interactions.
• use_gpu_pipeline: (bool), Whether to enable the GPU pipeline for physics processing. When True, computations are offloaded to the GPU, improving performance for large simulations.
• worker_thread_count: (int), The number of threads allocated for physics processing. A higher count can improve performance but may increase CPU usage.
• use_fabric: (bool), TODO
• enable_scene_query_support: (bool), TODO
• gpu_max_rigid_contact_count: (int), The maximum number of rigid body contacts that the GPU can handle per frame.
• gpu_max_rigid_patch_contact_count: (int), The maximum number of patch contacts between rigid bodies that the GPU can process per frame.
• gpu_found_lost_pairs_capacity: (int), The capacity for handling found and lost contact pairs in the GPU pipeline. Determines how many pairs can be processed before overflow occurs.
• gpu_total_aggregate_pairs_capacity: (int), The total capacity for aggregate pairs (grouped objects) that can be processed by the GPU.
• gpu_max_soft_body_contacts: (int), The maximum number of soft body contacts the GPU can process. Soft bodies include deformable objects such as cloth or elastic materials.
• gpu_max_particle_contacts: (int), The maximum number of particle contacts the GPU can process. This typically applies to particle-based simulations such as fluids or granular materials.
• gpu_heap_capacity: (int), The heap memory capacity reserved for GPU physics processing.
• gpu_temp_buffer_capacity: (int), The temporary buffer size for the GPU pipeline during physics computations.
• gpu_max_num_partions: (int), The maximum number of partitions the GPU can handle, related to splitting the physics scene into smaller sections for processing.
• gpu_collision_stack_size: (int), The stack size allocated for handling collisions on the GPU.
• solver_type: (str), The type of solver used for physics simulation. Common values include PBD (Position-Based Dynamics) or TGS (Temporal Gauss-Seidel).
• enable_stabilization: (bool), Whether to enable stabilization for the solver, which helps reduce jitter and improve the stability of simulations involving contact or collision.
• bounce_threshold_velocity: (float), The velocity threshold for bounce calculations. Objects with a velocity below this threshold will not bounce upon impact.
• friction_offset_threshold: (float), The offset distance used when applying friction between objects in contact. Affects how friction is calculated based on the distance between objects.
• friction_correlation_distance: (float), The correlation distance for friction calculation. Defines the area over which friction is applied between two surfaces.
• enable_ccd: (bool), Whether to enable Continuous Collision Detection (CCD). CCD prevents fast-moving objects from passing through one another by performing more frequent collision checks.

Note

• GPU-specific settings are important for optimizing large simulations, especially when dealing with rigid bodies, soft bodies, and particles.
• The number of substeps and solver type significantly impact the accuracy and stability of the physics simulation.
• Using the GPU pipeline and adjusting thread count allows for performance improvements, particularly in complex scenes.
• The stabilization options and collision detection settings like CCD help avoid errors in physics calculations, such as objects passing through one another or jittering at rest.

Example:

physics_scene:
  dt: 0.16666
  gravity: [0.0, 0.0, -1.62]
  enable_ccd: true
  enable_stabilization: false
  solver_type: PGS
  use_gpu_pipeline: false