Force Field Introduction
The APEX ForceField module creates effects with APEX Basic IOS particles and APEX Particle IOS particles (based on PhysX 3 Particles). It will also work with PhysX 3.x objects such as particles and rigid bodies. The combination of APEX ForceField and APEX Particles allows a particle system that can be used to create a wide variety of force field effects. Good targets for APEX ForceField are things like explosions.
Limitations: The APEX Force Field module only supports PhysX 3.x on Windows, so it may not be included in all APEX distributions. ForceFields only interact with particles and rigid bodies at this point. Support for interaction with cloth will be added in a future APEX release.
ForceField Assets
This link describles all of the ForceField asset parameters.
ForceField Actors
This link describles all of the ForceField actor parameters.
Interaction with PhysX Shapes
ForceField actors can interact with PhysX shapes if the collision filtering settings are set correctly (set in the ForceField asset or actor).
Parameters
Lifetime
Force field lifetime determines how long a force field actor is active after creation.
Strength
Force field strength determines the amount of strength the force field applies to objects it interacts with. Strength magnitude is constant in the include shape of the actor, unless a spacial falloff is specified. Direction of force is dependent on the coordinate system type for the force field actor.
Spacial Falloff
Spacial falloff affects the strength of the force field in the include shape, depending on the distance of the point from the center of the force field.
Falloff Types
There are 3 predefined fallof shapes that can be used to configure spacial falloff.
The start and end distances for the falloff can be defined, and the force field strength between these distances will be scaled depending on the falloff type used.
Include Shapes
There are 5 different include shapes that can be used with a force field actor. Currently, only one include shape is supported for each force field actor. The include shape defines the space in which a force field acts in. The pose of the include shape can be used to rotate it, or to position it as an offset from the force field actor’s position.
To define the dimensions of the include shape and to position it relative to the force field actor, refer to the following table:
| Shape | x | y | z | position (0,0,0) | orientation |
|---|---|---|---|---|---|
| sphere | radius | center of sphere | |||
| capsule | radius | height | half height | vertical | |
| cylinder | radius | height | half height | vertical | |
| cone | top radius | height | bottom radius | half height | vertical |
| box | half dimension | half dimension | half dimension | center of box | as coordinates |
Noise
In order to add randomness, noise can be applied to force fields. Simplex noise is used here. Strength value, space scale, time scale and noise octaves parameters can be used to configure the characteristics of noise to be added.
Force Field Types
Spherical Force Field
The only force field type supported for now is the spherical force field. Spherical force fields creates an area where forces act in a direction radially outwards from the center of the force field. Falloff distance is also calculated based on the distance from the center of this force field.
Debug Visualization
All APEX modules come with debug visualization rendering, to help understand what is happening in an APEX scene. When you hit the V key in SimpleForceField, default APEX visualization rendering is turned on, as well as default PhysX SDK visualization.
Click here for a list of the Forcefield debug visualization parameters
For general information on how to use debug visualization within APEX, please see Debug Visualization.
Errors and Warnings
APEX ForceField outputs the following error and warning messages using the standard APEX error stream.
| ERROR CODE | MESSAGE | Explanation |
|---|---|---|
| APEX_INVALID_OPERATION | Not yet implemented! | The ForceField Module does not support dynamically editing the NvParameterized::Interface |
| APEX_INVALID_OPERATION | Not implemented! | The ForceField module does not support preparing an asset for another platform |
| APEX_DEBUG_WARNING | Driver error = %04d from file <%s>, line %i. | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - invalid value | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - out of memory | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - not initialized | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - launch failure | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - out of resources | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - lauch timeout | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - invalid context | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - error unknown | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - error deitialized | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - error invalid handle | |
| APEX_DEBUG_WARNING | FORCEFIELD FATAL ERROR - unknown error | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - u dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - v dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - v dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - u,v,w layout mismatch | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - u has no ghost cells | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - v has no ghost cells | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - w has no ghost cells | |
| APEX_DEBUG_WARNING | [ERROR] Advection3DDevice::initialize_storage - garbage hx,hy,hz value | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionMacCormack3DDeviceF::initialize_storage - error allocating extra grids | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDeviceF::invoke_kernel_downsample - bad level = %d | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDevice::invoke_kernel_downsample - CUDA error “%s” | A CUDA error occurred. A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDeviceF::invoke_kernel_upsample - bad level = %d | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDevice::invoke_kernel_upsample - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDevice::invoke_kernel_apply_upwind - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | Before BC: Max u at level %d = %f | |
| APEX_DEBUG_WARNING | After: Max u at level %d = %f | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDeviceF::solve - garbage req_dt %f! | |
| APEX_DEBUG_WARNING | level %d | |
| APEX_DEBUG_WARNING | [ERROR] AdvectionUpwind3DDeviceF::solve - too fast level = %d, _num_levels = %d! | |
| APEX_DEBUG_WARNING | Max u at level %d = %f | |
| APEX_DEBUG_WARNING | Max deriv_u at level %d = %f | |
| APEX_DEBUG_WARNING | [ERROR] Advection3D::initialize_storage - error allocating derivative grids | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_boundary_conditions_level1_nocorners - invalid boundary condition types %d, %d, %d, %d, %d,%d | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_boundary_conditions_level1_nocorners - must have at least 1 ghost point | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_boundary_conditions_level1_nocorners - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - invalid boundary condition types %d, %d, %d, %d, %d,%d | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - layout mismatch | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - must have at least 1 ghost point | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - v_grid dimension mismatch (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - w_grid dimension mismatch (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - CUDA error in x “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - CUDA error in y “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_mac_boundary_conditions_level1 - CUDA error in z “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] apply_3d_boundary_conditions_level1_nocorners - invalid boundary condition types %d, %d, %d, %d, %d,%d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDeviceT::clear_zero - cudaMemset failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_interior_data - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_interior_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_all_data - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_interior_data - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_interior_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_all_data - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::linear_combination - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDeviceF::linear_combination - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::linear_combination - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::linear_combination - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDeviceF::linear_combination - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid1DDevice::init - gpu buffer alloc failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_interior_data - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_interior_data - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::linear_combination - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::linear_combination - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::linear_combination - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::init - host buffer alloc failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_interior_data - nx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_interior_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_all_data - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_all_data - cudaMemcpy failed with %s | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::copy_all_data - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost copy_partial_data_async - pnx mismatch: %d != %d | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDeviceT::clear_zero - cudaMemset failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDeviceF::clear - CUDA error | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDeviceF::clear - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - non specialized function called | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::linear_combination - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDeviceF::linear_combination - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::linear_combination - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::linear_combination - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDeviceF::linear_combination - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] Grid3DDevice::init - gpu buffer alloc failed | |
| APEX_DEBUG_WARNING | ERROR: calling base implementation of initCUDAFunction | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_interior_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_interior_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_interior_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::linear_combination - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid1DHost::linear_combination - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::init - host buffer alloc failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_all_data - cudaMemcpy failed | |
| APEX_DEBUG_WARNING | [ERROR] Grid3DHost::copy_all_data - mismatch: (%d, %d, %d) != (%d, %d, %d) | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3DDeviceF::invoke_kernel_calculate_relax - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3DDeviceF::invoke_kernel_calculate_residual - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3DDeviceF::invoke_kernel_restrict - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3DDeviceF::invoke_kernel_prolong - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - garbage hx,hy,hz value %f %f %f | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::relax - failed at level %d | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::restrict_residuals - failed at level %d -> %d | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::prolong - failed at level %d -> %d | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::apply_boundary_conditions - failed at level %d | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::apply_boundary_conditions - failed at level %d | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3::initialize_storage - error in grid calculation | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - rhs has invalid ghost cells (%d,%d,%d), must be >= 1 | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - rhs dimension mismatch (%d,%d,%d) != (%d,%d,%d) | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - could not initialize _r_grid[0] | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - could not initialize _u_grid[0] | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - could not initialize _u_grid[%d] | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - could not initialize _b_grid[%d] | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - could not initialize _r_grid[%d] | |
| APEX_DEBUG_WARNING | [ERROR] MultigridPressure3D::initialize_storage - grid dimension mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::convert_bc_to_poisson_eqn - invalid boundary condition type %d | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::initialize_base_storage - u dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::initialize_base_storage - v dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::initialize_base_storage - v dimensions mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::initialize_base_storage - u,v,w layout mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_base_storage - must have at least one ghost cell on all sides | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DBase::initialize_base_storage - garbage hx,hy,hz value | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::calculate_divergence - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::subtract_grad_p - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::solve - could not enforce boundary conditions | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::solve - could not calculate divergence | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::solve - could not solve for pressure | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::solve - could not subtract gradient of pressure | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::solve - could not enforce boundary conditions | |
| APEX_DEBUG_WARNING | Max divergence: before = %.010f, after = %.010f (reduction %fx) | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_storage - failed to initialize base storage | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_storage - failed to initialize divergence | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_storage - divergence layout mismatch | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_storage - failed to initialize pressure_solver | |
| APEX_DEBUG_WARNING | [ERROR] ProjectDivergence3DDevice::initialize_storage - pressure layout mismatch | |
| APEX_DEBUG_WARNING | ERROR: calling base implementation of initCUDAFunction | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_3d - position arrays do not have matching sizes | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_3d - CUDA error | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] sample_points_3d - position arrays do not have matching sizes | |
| APEX_DEBUG_WARNING | [ERROR] sample_weighted_points_3d - CUDA error | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] calculate_velocity_weights - CUDA error “%s” | A CUDA error occurred. |
| APEX_DEBUG_WARNING | [ERROR] sample_points_mac_grid_3d - failed on u sampling | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_mac_grid_3d - failed on v sampling | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_mac_grid_3d - failed on w sampling | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_minmax_3d - position arrays do not have matching sizes | |
| APEX_DEBUG_WARNING | [ERROR] sample_points_minmax_3d - CUDA error “%s” | A CUDA error occurred. |