Open Dynamics Engine
|
Modules | |
Automatic Enabling and Disabling | |
Damping | |
Classes | |
struct | dWorldStepReserveInfo |
Memory reservation policy descriptor structure for world stepping functions. More... | |
Functions | |
ODE_API dWorldID | dWorldCreate (void) |
Create a new, empty world and return its ID number. More... | |
ODE_API void | dWorldDestroy (dWorldID world) |
Destroy a world and everything in it. More... | |
ODE_API void | dWorldSetGravity (dWorldID, dReal x, dReal y, dReal z) |
Set the world's global gravity vector. More... | |
ODE_API void | dWorldGetGravity (dWorldID, dVector3 gravity) |
Get the gravity vector for a given world. | |
ODE_API void | dWorldSetERP (dWorldID, dReal erp) |
Set the global ERP value, that controls how much error correction is performed in each time step. More... | |
ODE_API dReal | dWorldGetERP (dWorldID) |
Get the error reduction parameter. More... | |
ODE_API void | dWorldSetCFM (dWorldID, dReal cfm) |
Set the global CFM (constraint force mixing) value. More... | |
ODE_API dReal | dWorldGetCFM (dWorldID) |
Get the constraint force mixing value. More... | |
ODE_API void | dWorldSetStepIslandsProcessingMaxThreadCount (dWorldID w, unsigned count) |
Set maximum threads to be used for island stepping. More... | |
ODE_API unsigned | dWorldGetStepIslandsProcessingMaxThreadCount (dWorldID w) |
Get maximum threads that are allowed to be used for island stepping. More... | |
ODE_API int | dWorldUseSharedWorkingMemory (dWorldID w, dWorldID from_world) |
Set the world to use shared working memory along with another world. More... | |
ODE_API void | dWorldCleanupWorkingMemory (dWorldID w) |
Release internal working memory allocated for world. More... | |
ODE_API int | dWorldSetStepMemoryReservationPolicy (dWorldID w, const dWorldStepReserveInfo *policyinfo) |
Set memory reservation policy for world to be used with simulation stepping functions. More... | |
ODE_API int | dWorldSetStepMemoryManager (dWorldID w, const dWorldStepMemoryFunctionsInfo *memfuncs) |
Set memory manager for world to be used with simulation stepping functions. More... | |
ODE_API void | dWorldSetStepThreadingImplementation (dWorldID w, const dThreadingFunctionsInfo *functions_info, dThreadingImplementationID threading_impl) |
Assign threading implementation to be used for [quick]stepping the world. More... | |
ODE_API int | dWorldStep (dWorldID w, dReal stepsize) |
Step the world. More... | |
ODE_API int | dWorldQuickStep (dWorldID w, dReal stepsize) |
Quick-step the world. More... | |
ODE_API void | dWorldImpulseToForce (dWorldID, dReal stepsize, dReal ix, dReal iy, dReal iz, dVector3 force) |
Converts an impulse to a force. More... | |
ODE_API void | dWorldSetQuickStepNumIterations (dWorldID, int num) |
Set the number of iterations that the QuickStep method performs per step. More... | |
ODE_API int | dWorldGetQuickStepNumIterations (dWorldID) |
Get the number of iterations that the QuickStep method performs per step. More... | |
ODE_API void | dWorldSetQuickStepW (dWorldID, dReal over_relaxation) |
Set the SOR over-relaxation parameter. More... | |
ODE_API dReal | dWorldGetQuickStepW (dWorldID) |
Get the SOR over-relaxation parameter. More... | |
ODE_API void | dWorldSetContactMaxCorrectingVel (dWorldID, dReal vel) |
Set the maximum correcting velocity that contacts are allowed to generate. More... | |
ODE_API dReal | dWorldGetContactMaxCorrectingVel (dWorldID) |
Get the maximum correcting velocity that contacts are allowed to generated. | |
ODE_API void | dWorldSetContactSurfaceLayer (dWorldID, dReal depth) |
Set the depth of the surface layer around all geometry objects. More... | |
ODE_API dReal | dWorldGetContactSurfaceLayer (dWorldID) |
Get the depth of the surface layer around all geometry objects. More... | |
The world object is a container for rigid bodies and joints. Objects in different worlds can not interact, for example rigid bodies from two different worlds can not collide.
All the objects in a world exist at the same point in time, thus one reason to use separate worlds is to simulate systems at different rates. Most applications will only need one world.
ODE_API void dWorldCleanupWorkingMemory | ( | dWorldID | w | ) |
Release internal working memory allocated for world.
The worlds allocate working memory internally for simulation stepping. This function can be used to free world's internal memory cache in case if number of objects/joints in the world decreases significantly. By default, internal allocation policy is used to only increase cache size as necessary and never decrease it.
If a world shares its working memory with other worlds the cache deletion affects all the linked worlds. However the shared status itself remains intact.
The function call does affect neither memory reservation policy nor memory manager.
w | The world to release working memory for. |
ODE_API dWorldID dWorldCreate | ( | void | ) |
Create a new, empty world and return its ID number.
ODE_API void dWorldDestroy | ( | dWorldID | world | ) |
Destroy a world and everything in it.
This includes all bodies, and all joints that are not part of a joint group. Joints that are part of a joint group will be deactivated, and can be destroyed by calling, for example, dJointGroupEmpty().
world | the identifier for the world the be destroyed. |
ODE_API dReal dWorldGetCFM | ( | dWorldID | ) |
Get the constraint force mixing value.
ODE_API dReal dWorldGetContactSurfaceLayer | ( | dWorldID | ) |
Get the depth of the surface layer around all geometry objects.
ODE_API dReal dWorldGetERP | ( | dWorldID | ) |
Get the error reduction parameter.
ODE_API int dWorldGetQuickStepNumIterations | ( | dWorldID | ) |
Get the number of iterations that the QuickStep method performs per step.
ODE_API dReal dWorldGetQuickStepW | ( | dWorldID | ) |
Get the SOR over-relaxation parameter.
ODE_API unsigned dWorldGetStepIslandsProcessingMaxThreadCount | ( | dWorldID | w | ) |
Get maximum threads that are allowed to be used for island stepping.
Please read commentaries to dWorldSetStepIslandsProcessingMaxThreadCount
for important information regarding the value returned.
w | The world queried |
ODE_API void dWorldImpulseToForce | ( | dWorldID | , |
dReal | stepsize, | ||
dReal | ix, | ||
dReal | iy, | ||
dReal | iz, | ||
dVector3 | force | ||
) |
Converts an impulse to a force.
ODE_API int dWorldQuickStep | ( | dWorldID | w, |
dReal | stepsize | ||
) |
Quick-step the world.
This uses an iterative method that takes time on the order of m*N and memory on the order of m, where m is the total number of constraint rows N is the number of iterations. For large systems this is a lot faster than dWorldStep(), but it is less accurate.
QuickStep is great for stacks of objects especially when the auto-disable feature is used as well. However, it has poor accuracy for near-singular systems. Near-singular systems can occur when using high-friction contacts, motors, or certain articulated structures. For example, a robot with multiple legs sitting on the ground may be near-singular.
There are ways to help overcome QuickStep's inaccuracy problems:
Increasing the number of QuickStep iterations may help a little bit, but it is not going to help much if your system is really near singular.
Failure result status means that the memory allocation has failed for operation. In such a case all the objects remain in unchanged state and simulation can be retried as soon as more memory is available.
w | The world to be stepped |
stepsize | The number of seconds that the simulation has to advance. |
ODE_API void dWorldSetCFM | ( | dWorldID | , |
dReal | cfm | ||
) |
Set the global CFM (constraint force mixing) value.
cfm | Typical values are in the range {10^{-9}} – 1. The default is 10^-5 if single precision is being used, or 10^-10 if double precision is being used. |
ODE_API void dWorldSetContactMaxCorrectingVel | ( | dWorldID | , |
dReal | vel | ||
) |
Set the maximum correcting velocity that contacts are allowed to generate.
vel | The default value is infinity (i.e. no limit). |
ODE_API void dWorldSetContactSurfaceLayer | ( | dWorldID | , |
dReal | depth | ||
) |
Set the depth of the surface layer around all geometry objects.
depth | The default value is zero. |
ODE_API void dWorldSetERP | ( | dWorldID | , |
dReal | erp | ||
) |
Set the global ERP value, that controls how much error correction is performed in each time step.
dWorldID | the identifier of the world. |
erp | Typical values are in the range 0.1–0.8. The default is 0.2. |
ODE_API void dWorldSetGravity | ( | dWorldID | , |
dReal | x, | ||
dReal | y, | ||
dReal | z | ||
) |
Set the world's global gravity vector.
The units are m/s^2, so Earth's gravity vector would be (0,0,-9.81), assuming that +z is up. The default is no gravity, i.e. (0,0,0).
ODE_API void dWorldSetQuickStepNumIterations | ( | dWorldID | , |
int | num | ||
) |
Set the number of iterations that the QuickStep method performs per step.
num | The default is 20 iterations. |
ODE_API void dWorldSetQuickStepW | ( | dWorldID | , |
dReal | over_relaxation | ||
) |
Set the SOR over-relaxation parameter.
over_relaxation | value to use by SOR |
ODE_API void dWorldSetStepIslandsProcessingMaxThreadCount | ( | dWorldID | w, |
unsigned | count | ||
) |
Set maximum threads to be used for island stepping.
The actual number of threads that is going to be used will be the minimum of this limit and number of threads in the threading pool. By default there is no limit (dWORLDSTEP_THREADCOUNT_UNLIMITED
).
Note: Setting a limit for island stepping does not affect threading at lower levels in stepper functions. The sub-calls scheduled from them can be executed in as many threads as there are available in the pool.
w | The world affected |
count | Thread count limit value for island stepping |
ODE_API int dWorldSetStepMemoryManager | ( | dWorldID | w, |
const dWorldStepMemoryFunctionsInfo * | memfuncs | ||
) |
Set memory manager for world to be used with simulation stepping functions.
The function allows to customize memory manager to be used for internal memory allocation during simulation for a world. By default, dAlloc/
manager is used.dRealloc/
memorydFree
based
Passing memfuncs argument as NULL results in memory manager being reset to default one as if the world has been just created. The content of memfuncs structure is copied internally and does not need to remain valid after the call returns.
If the world uses working memory sharing, changing memory manager affects all the worlds linked together.
Failure result status means a memory allocation failure.
w | The world to change memory reservation policy for. |
memfuncs | Null or a pointer to memory manager descriptor structure. |
ODE_API int dWorldSetStepMemoryReservationPolicy | ( | dWorldID | w, |
const dWorldStepReserveInfo * | policyinfo | ||
) |
Set memory reservation policy for world to be used with simulation stepping functions.
The function allows to customize reservation policy to be used for internal memory which is allocated to aid simulation for a world. By default, values of dWORLDSTEP_RESERVEFACTOR_DEFAULT
and dWORLDSTEP_RESERVESIZE_DEFAULT
are used.
Passing policyinfo argument as NULL results in reservation policy being reset to defaults as if the world has been just created. The content of policyinfo structure is copied internally and does not need to remain valid after the call returns.
If the world uses working memory sharing, changing memory reservation policy affects all the worlds linked together.
Failure result status means a memory allocation failure.
w | The world to change memory reservation policy for. |
policyinfo | Null or a pointer to policy descriptor structure. |
ODE_API void dWorldSetStepThreadingImplementation | ( | dWorldID | w, |
const dThreadingFunctionsInfo * | functions_info, | ||
dThreadingImplementationID | threading_impl | ||
) |
Assign threading implementation to be used for [quick]stepping the world.
w | The world to change threading implementation for. |
functions_info | Pointer to threading functions structure |
threading_impl | ID of threading implementation object |
ODE_API int dWorldStep | ( | dWorldID | w, |
dReal | stepsize | ||
) |
Step the world.
This uses a "big matrix" method that takes time on the order of m^3 and memory on the order of m^2, where m is the total number of constraint rows. For large systems this will use a lot of memory and can be very slow, but this is currently the most accurate method.
Failure result status means that the memory allocation has failed for operation. In such a case all the objects remain in unchanged state and simulation can be retried as soon as more memory is available.
w | The world to be stepped |
stepsize | The number of seconds that the simulation has to advance. |
Set the world to use shared working memory along with another world.
The worlds allocate working memory internally for simulation stepping. This memory is cached among the calls to dWordStep
and dWorldQuickStep
. Similarly, several worlds can be set up to share this memory caches thus reducing overall memory usage by cost of making worlds inappropriate for simultaneous simulation in multiple threads.
If null value is passed for from_world parameter the world is detached from sharing and returns to defaults for working memory, reservation policy and memory manager as if just created. This can also be used to enable use of shared memory for a world that has already had working memory allocated privately. Normally using shared memory after a world has its private working memory allocated is prohibited.
Allocation policy used can only increase world's internal reserved memory size and never decreases it. dWorldCleanupWorkingMemory
can be used to release working memory for a world in case if number of objects/joint decreases significantly in it.
With sharing working memory worlds also automatically share memory reservation policy and memory manager. Thus, these parameters need to be customized for initial world to be used as sharing source only.
If worlds share working memory they must also use compatible threading implementations (i.e. it is illegal for one world to perform stepping with self-threaded implementation when the other world is assigned a multi-threaded implementation). For more information read section about threading approaches in ODE.
Failure result status means a memory allocation failure.
w | The world to use the shared memory with. |
from_world | Null or the world the shared memory is to be used from. |