Data Structures
struct	FlexExtAsset

struct	FlexExtInstance

struct	FlexExtForceField

Enumerations
enum	FlexForceExtMode { eFlexExtModeForce = 0, eFlexExtModeImpulse = 1, eFlexExtModeVelocityChange = 2 }

Functions
FLEX_API int	flexExtCreateWeldedMeshIndices (const float vertices, int numVertices, int uniqueVerts, int *originalToUniqueMap, float threshold)

FLEX_API FlexExtAsset *	flexExtCreateClothFromMesh (const float particles, int numVertices, const int indices, int numTriangles, float stretchStiffness, float bendStiffness, float tetherStiffness, float tetherGive, float pressure)

FLEX_API FlexExtAsset *	flexExtCreateRigidFromMesh (const float vertices, int numVertices, const int indices, int numTriangleIndices, float radius)

FLEX_API void	flexExtDestroyAsset (FlexExtAsset *asset)

FLEX_API FlexExtContainer *	flexExtCreateContainer (FlexSolver *solver, int maxParticles)

FLEX_API void	flexExtDestroyContainer (FlexExtContainer *container)

FLEX_API int	flexExtAllocParticles (FlexExtContainer container, int n, int indices)

FLEX_API void	flexExtFreeParticles (FlexExtContainer container, int n, const int indices)

FLEX_API int	flexExtGetActiveList (FlexExtContainer container, int indices)

FLEX_API FlexExtInstance *	flexExtCreateInstance (FlexExtContainer container, const FlexExtAsset asset, const float *transform, float vx, float vy, float vz, int phase, float invMassScale)

FLEX_API void	flexExtDestroyInstance (FlexExtContainer container, const FlexExtInstance instance)

FLEX_API void	flexExtGetParticleData (FlexExtContainer container, float particles, float velocities, int phases, float *normals)

FLEX_API void	flexExtGetTriangleData (FlexExtContainer container, int indices, float *normals)

FLEX_API void	flexExtGetRigidData (FlexExtContainer container, float rotations, float *positions)

FLEX_API void	flexExtTickContainer (FlexExtContainer container, float dt, int numSubsteps, FlexTimers timers=NULL)

FLEX_API void	flexExtPushToDevice (FlexExtContainer *container)

FLEX_API void	flexExtPullFromDevice (FlexExtContainer *container)

FLEX_API void	flexExtSetForceFields (FlexExtContainer container, const FlexExtForceField forceFields, int numForceFields, FlexMemory source)

FLEX_API void	flexExtApplyForceFields (FlexExtContainer *container, float dt)

Data Structure Documentation

struct FlexExtAsset

Represents a group of particles and constraints, each asset can be instanced into a simulation using flexExtCreateInstance

Data Fields
float *	mParticles	Local space particle positions, x,y,z,1/mass.
int	mNumParticles	Number of particles.
int *	mSpringIndices	Spring indices.
float *	mSpringCoefficients	Spring coefficients.
float *	mSpringRestLengths	Spring rest-lengths.
int	mNumSprings	Number of springs.
float	mRigidStiffness	Rigid body constraint stiffness.
float	mRigidCenter[3]	Local space center of mass of the particles.
int *	mTriangleIndices	Indexed triangle mesh for clothing.
int	mNumTriangles	Number of triangles.
bool	mInflatable	Whether an inflatable constraint should be added.
float	mInflatableVolume	The rest volume for the inflatable constraint.
float	mInflatablePressure	How much over the rest volume the inflatable should attempt to maintain.
float	mInflatableStiffness	How stiff the inflatable is.

struct FlexExtInstance

Represents an instance of a FlexAsset in a container

Data Fields
int *	mParticleIndices	Simulation particle indices.
int	mNumParticles	Number of simulation particles.
int	mTriangleIndex	Index in the container's triangle array.
int	mRigidIndex	Index in the container's rigid body constraints array.
int	mInflatableIndex	Index in the container's inflatables array.
const FlexExtAsset *	mAsset	Source asset used to create this instance.
void *	mUserData	User data pointer.

struct FlexExtForceField

Force field data, currently just supports radial fields

Data Fields
float	mPosition[3]	Center of force field.
float	mRadius	Radius of the force field.
float	mStrength	Strength of the force field.
FlexForceExtMode	mMode	Mode of field application.
bool	mLinearFalloff	Linear or no falloff.

Enumeration Type Documentation

enum FlexForceExtMode

Controls the way that force fields affect particles

Enumerator
eFlexExtModeForce	Apply field value as a force.
eFlexExtModeImpulse	Apply field value as an impulse.
eFlexExtModeVelocityChange	Apply field value as a velocity change.

Function Documentation

FLEX_API int flexExtCreateWeldedMeshIndices	(	const float *	vertices,
		int	numVertices,
		int *	uniqueVerts,
		int *	originalToUniqueMap,
		float	threshold
	)

Create an index buffer of unique vertices in the mesh

Parameters

[in]	vertices	A pointer to an array of float3 positions
[in]	numVertices	The number of vertices in the mesh
[out]	uniqueVerts	A list of unique mesh vertex indices, should be numVertices in length (worst case all verts are unique)
[out]	originalToUniqueMap	Mapping from the original vertex index to the unique vertex index, should be numVertices in length
[in]	threshold	The distance below which two vertices are considered duplicates

Returns: The number of unique vertices in the mesh

FLEX_API FlexExtAsset* flexExtCreateClothFromMesh	(	const float *	particles,
		int	numVertices,
		const int *	indices,
		int	numTriangles,
		float	stretchStiffness,
		float	bendStiffness,
		float	tetherStiffness,
		float	tetherGive,
		float	pressure
	)

Create a cloth asset consisting of stretch and bend distance constraints given an indexed triangle mesh. Stretch constraints will be placed along triangle edges, while bending constraints are placed over two edges.

Parameters

[in]	particles	Positions and masses of the particles in the format [x, y, z, 1/m]
[in]	numVertices	The number of particles
[in]	indices	The triangle indices, these should be 'welded' using flexExtCreateWeldedMeshIndices() first
[in]	numTriangles	The number of triangles
[in]	stretchStiffness	The stiffness coefficient for stretch constraints
[in]	bendStiffness	The stiffness coefficient used for bending constraints
[in]	tetherStiffness	If > 0.0f then the function will create tether's attached to particles with zero inverse mass. These are unilateral, long-range attachments, which can greatly reduce stretching even at low iteration counts.
[in]	tetherGive	Because tether constraints are so effective at reducing stiffness, it can be useful to allow a small amount of extension before the constraint activates.
[in]	pressure	If > 0.0f then a volume (pressure) constraint will also be added to the asset, the rest volume and stiffness will be automatically computed by this function

Returns: A pointer to an asset structure holding the particles and constraints

FLEX_API FlexExtAsset* flexExtCreateRigidFromMesh	(	const float *	vertices,
		int	numVertices,
		const int *	indices,
		int	numTriangleIndices,
		float	radius
	)

Create a rigid body asset from a closed triangle mesh. The mesh is first voxelized at a spacing specified by the radius, and particles are placed at occupied voxels.

Parameters

[in]	vertices	Vertices of the triangle mesh
[in]	numVertices	The number of vertices
[in]	indices	The triangle indices
[in]	numTriangleIndices	The number of triangles indices (triangles*3)
[in]	radius	The spacing used for voxelization, note that the number of voxels grows proportional to the inverse cube of radius, currently this method limits construction to resolutions < 64^3

Returns: A pointer to an asset structure holding the particles and constraints

FLEX_API void flexExtDestroyAsset ( FlexExtAsset * asset )

Frees all memory associated with an asset created by one of the creation methods param[in] asset The asset to destroy.

FLEX_API FlexExtContainer* flexExtCreateContainer	(	FlexSolver *	solver,
		int	maxParticles
	)

Creates a wrapper object around a Flex solver that can hold assets / instances

Parameters

[in]	solver	The solver to wrap
[in]	maxParticles	The maximum number of particles to manage

Returns: A pointer to the new container

FLEX_API void flexExtDestroyContainer ( FlexExtContainer * container )

Frees all memory associated with a container

Parameters

[in] container The container to destroy

FLEX_API int flexExtAllocParticles	(	FlexExtContainer *	container,
		int	n,
		int *	indices
	)

Allocates particles in the container.

Parameters

[in]	container	The container to allocate out of
[in]	n	The number of particles to allocate
[out]	indices	An n-length array of ints that will store the indices to the allocated particles

FLEX_API void flexExtFreeParticles	(	FlexExtContainer *	container,
		int	n,
		const int *	indices
	)

Free allocated particles

Parameters

[in]	container	The container to free from
[in]	n	The number of particles to free
[in]	indices	The indices of the particles to free

FLEX_API int flexExtGetActiveList	(	FlexExtContainer *	container,
		int *	indices
	)

Retrives the indices of all active particles

Parameters

[in]	container	The container to free from
[out]	indices	Returns the number of active particles

Returns: The number of active particles

FLEX_API FlexExtInstance* flexExtCreateInstance	(	FlexExtContainer *	container,
		const FlexExtAsset *	asset,
		const float *	transform,
		float	vx,
		float	vy,
		float	vz,
		int	phase,
		float	invMassScale
	)

Creates an instance of an asset, the container will internally store a reference to the asset so it should remain valid for the instance lifetime. This method will allocate particles for the asset, assign their initial positions, velocity and phase.

Parameters

[in]	container	The container to spawn into
[in]	asset	The asset to be spawned
[in]	transform	A pointer to a 4x4 column major, column vector transform that specifies the initial world space configuration of the particles
[in]	vx	The velocity of the particles along the x axis
[in]	vy	The velocity of the particles along the y axis
[in]	vz	The velocity of the particles along the z axis
[in]	phase	The phase used for the particles
[in]	invMassScale	A factor applied to the per particle inverse mass

Returns: A pointer to the instance of the asset

FLEX_API void flexExtDestroyInstance	(	FlexExtContainer *	container,
		const FlexExtInstance *	instance
	)

Destoy an instance of an asset

Parameters

[in]	container	The container the instance belongs to
[in]	instance	The instance to destroy

FLEX_API void flexExtGetParticleData	(	FlexExtContainer *	container,
		float **	particles,
		float **	velocities,
		int **	phases,
		float **	normals
	)

Returns pointers to the internal data stored by the container. These are host-memory pointers, and will remain valid until the container is destroyed. They can be used to read and write particle data, but only after suitable synchronization. See flexExtTickContainer() for details.

Parameters

container	The container whose data should be accessed
particles	Receives a pointer to the particle position / mass data
velocities	Receives a pointer to the particle velocity data
phases	Receives a pointer to the particle phase data
normals	Receives a pointer to the particle normal data with 16 byte stride in format [nx, ny, nz, nw]

FLEX_API void flexExtGetTriangleData	(	FlexExtContainer *	container,
		int **	indices,
		float **	normals
	)

Access triangle constraint data, see flexExtGetParticleData() for notes on ownership.

Parameters

container	The container to retrive from
indices	Receives a pointer to the array of triangle index data
normals	Receives a pointer to an array of triangle normal data stored with 16 byte stride, i.e.: [nx, ny, nz]

FLEX_API void flexExtGetRigidData	(	FlexExtContainer *	container,
		float **	rotations,
		float **	positions
	)

Access rigid body constraint data, see flexExtGetParticleData() for notes on ownership.

Parameters

container	The container to retrive from
rotations	Receives a pointer to the array 3x3 rotation matrix data
positions	Receives a pointer to an array of rigid body translations in [x, y, z] format

FLEX_API void flexExtTickContainer	(	FlexExtContainer *	container,
		float	dt,
		int	numSubsteps,
		FlexTimers *	timers = `NULL`
	)

Updates the container, applies force fields, steps the solver forward in time, updates the host with the results synchronously. This is a helper function which performs a synchronous update using the following flow.

// async update GPU data
flexExtPushToDevice(container);
flexExtApplyForceFields(container):
// update solver
flexUpdateSolver(container, dt, iterations);
// async read data back to CPU
flexExtPullFromDevice(container);
// insert and wait on fence
flexSetFence();
flexWaitFence();
// read / write particle data on CPU
flexExtGetParticleData(container, particles, velocities, phases, normals);

Parameters

[in]	container	The container to update
[in]	dt	The time-step in seconds
[in]	numSubsteps	The number of substeps to perform
[in]	timers	Pointer to a Flex profiling structure, see flexUpdateSolver()

FLEX_API void flexExtPushToDevice ( FlexExtContainer * container )

Updates the device asynchronously, transfers any particle and constraint changes to the flex solver, expected to be called in the following sequence: flexExtPushToDevice, [flexExtApplyForceFields,] flexUpdateSolver, flexExtPullFromDevice, flexSynchronize

Parameters

[in] container The container to update

FLEX_API void flexExtPullFromDevice ( FlexExtContainer * container )

Updates the host asynchronously, transfers particle and constraint data back to he host, expected to be called in the following sequence: flexExtPushToDevice, [flexExtApplyForceFields,] flexUpdateSolver, flexExtPullFromDevice, flexSynchronize

Parameters

[in] container The container to update

FLEX_API void flexExtSetForceFields	(	FlexExtContainer *	container,
		const FlexExtForceField *	forceFields,
		int	numForceFields,
		FlexMemory	source
	)

FLEX_API void flexExtApplyForceFields	(	FlexExtContainer *	container,
		float	dt
	)

Data Structures

Enumerations

Functions

Data Structure Documentation

Enumeration Type Documentation

Function Documentation