protected Simulation(BufferPool bufferPool, SimulationAllocationSizes initialAllocationSizes)
{
BufferPool = bufferPool;
Shapes = new Shapes(bufferPool, initialAllocationSizes.ShapesPerType);
BroadPhase = new BroadPhase(bufferPool, initialAllocationSizes.Bodies, initialAllocationSizes.Bodies + initialAllocationSizes.Statics);
Bodies = new Bodies(bufferPool, Shapes, BroadPhase,
initialAllocationSizes.Bodies,
initialAllocationSizes.Islands,
initialAllocationSizes.ConstraintCountPerBodyEstimate);
Statics = new Statics(bufferPool, Shapes, Bodies, BroadPhase, initialAllocationSizes.Statics);
Solver = new Solver(Bodies, BufferPool, 8,
initialCapacity: initialAllocationSizes.Constraints,
initialIslandCapacity: initialAllocationSizes.Islands,
minimumCapacityPerTypeBatch: initialAllocationSizes.ConstraintsPerTypeBatch);
constraintRemover = new ConstraintRemover(BufferPool, Bodies, Solver);
Sleeper = new IslandSleeper(Bodies, Solver, BroadPhase, constraintRemover, BufferPool);
Awakener = new IslandAwakener(Bodies, Statics, Solver, BroadPhase, Sleeper, bufferPool);
Statics.awakener = Awakener;
Solver.awakener = Awakener;
Bodies.Initialize(Solver, Awakener);
PoseIntegrator = new PoseIntegrator(Bodies, Shapes, BroadPhase);
SolverBatchCompressor = new BatchCompressor(Solver, Bodies);
BodyLayoutOptimizer = new BodyLayoutOptimizer(Bodies, BroadPhase, Solver, bufferPool);
ConstraintLayoutOptimizer = new ConstraintLayoutOptimizer(Bodies, Solver);
}
/// <summary>
/// Constructs a simulation supporting dynamic movement and constraints with the specified narrow phase callbacks.
/// </summary>
/// <param name="bufferPool">Buffer pool used to fill persistent structures and main thread ephemeral resources across the engine.</param>
/// <param name="narrowPhaseCallbacks">Callbacks to use in the narrow phase.</param>
/// <param name="poseIntegratorCallbacks">Callbacks to use in the pose integrator.</param>
/// <param name="timestepper">Timestepper that defines how the simulation state should be updated.</param>
/// <param name="solverIterationCount">Number of iterations the solver should use.</param>
/// <param name="solverFallbackBatchThreshold">Number of synchronized batches the solver should maintain before falling back to a lower quality jacobi hybrid solver.</param>
/// <param name="initialAllocationSizes">Allocation sizes to initialize the simulation with. If left null, default values are chosen.</param>
/// <returns>New simulation.</returns>
public static Simulation Create <TNarrowPhaseCallbacks, TPoseIntegratorCallbacks>(
BufferPool bufferPool, TNarrowPhaseCallbacks narrowPhaseCallbacks, TPoseIntegratorCallbacks poseIntegratorCallbacks, ITimestepper timestepper,
int solverIterationCount = 8, int solverFallbackBatchThreshold = 64, SimulationAllocationSizes?initialAllocationSizes = null)
where TNarrowPhaseCallbacks : struct, INarrowPhaseCallbacks
where TPoseIntegratorCallbacks : struct, IPoseIntegratorCallbacks
{
if (initialAllocationSizes == null)
{
initialAllocationSizes = new SimulationAllocationSizes
{
Bodies = 4096,
Statics = 4096,
ShapesPerType = 128,
ConstraintCountPerBodyEstimate = 8,
Constraints = 16384,
ConstraintsPerTypeBatch = 256
};
}
var simulation = new Simulation(bufferPool, initialAllocationSizes.Value, solverIterationCount, solverFallbackBatchThreshold, timestepper);
var poseIntegrator = new PoseIntegrator <TPoseIntegratorCallbacks>(simulation.Bodies, simulation.Shapes, simulation.BroadPhase, poseIntegratorCallbacks);
simulation.PoseIntegrator = poseIntegrator;
var narrowPhase = new NarrowPhase <TNarrowPhaseCallbacks>(simulation,
DefaultTypes.CreateDefaultCollisionTaskRegistry(), DefaultTypes.CreateDefaultSweepTaskRegistry(),
narrowPhaseCallbacks, initialAllocationSizes.Value.Islands + 1);
DefaultTypes.RegisterDefaults(simulation.Solver, narrowPhase);
simulation.NarrowPhase = narrowPhase;
simulation.Sleeper.pairCache = narrowPhase.PairCache;
simulation.Awakener.pairCache = narrowPhase.PairCache;
simulation.Solver.pairCache = narrowPhase.PairCache;
simulation.BroadPhaseOverlapFinder = new CollidableOverlapFinder <TNarrowPhaseCallbacks>(narrowPhase, simulation.BroadPhase);
//We defer initialization until after all the other simulation bits are constructed.
poseIntegrator.Callbacks.Initialize(simulation);
narrowPhase.Callbacks.Initialize(simulation);
return(simulation);
}
//TODO: I wonder if people will abuse the dt-as-parameter to the point where we should make it a field instead, like it effectively was in v1.
/// <summary>
/// Performs one timestep of the given length.
/// </summary>
/// <remarks>
/// Be wary of variable timesteps. They can harm stability. Whenever possible, keep the timestep the same across multiple frames unless you have a specific reason not to.
/// </remarks>
/// <param name="dt">Duration of the time step in time.</param>
public void Timestep(float dt, IThreadDispatcher threadDispatcher = null)
{
ProfilerClear();
ProfilerStart(this);
//Note that the first behavior-affecting stage is actually the pose integrator. This is a shift from v1, where collision detection went first.
//This is a tradeoff:
//1) Any externally set velocities will be integrated without input from the solver. The v1-style external velocity control won't work as well-
//the user would instead have to change velocities after the pose integrator runs. This isn't perfect either, since the pose integrator is also responsible
//for updating the bounding boxes used for collision detection.
//2) By bundling bounding box calculation with pose integration, you avoid redundant pose and velocity memory accesses.
//3) Generated contact positions are in sync with the integrated poses.
//That's often helpful for gameplay purposes- you don't have to reinterpret contact data when creating graphical effects or positioning sound sources.
//TODO: This is something that is possibly worth exposing as one of the generic type parameters. Users could just choose the order arbitrarily.
//Or, since you're talking about something that happens once per frame instead of once per collision pair, just provide a simple callback.
//(Or maybe an enum even?)
//#1 is a difficult problem, though. There is no fully 'correct' place to change velocities. We might just have to bite the bullet and create a
//inertia tensor/bounding box update separate from pose integration. If the cache gets evicted in between (virtually guaranteed unless no stages run),
//this basically means an extra 100-200 microseconds per frame on a processor with ~20GBps bandwidth simulating 32768 bodies.
//Note that the reason why the pose integrator comes first instead of, say, the solver, is that the solver relies on world space inertias calculated by the pose integration.
//If the pose integrator doesn't run first, we either need
//1) complicated on demand updates of world inertia when objects are added or local inertias are changed or
//2) local->world inertia calculation before the solver.
ProfilerStart(PoseIntegrator);
PoseIntegrator.Update(dt, BufferPool, threadDispatcher);
ProfilerEnd(PoseIntegrator);
ProfilerStart(BroadPhase);
BroadPhase.Update(threadDispatcher);
ProfilerEnd(BroadPhase);
ProfilerStart(BroadPhaseOverlapFinder);
BroadPhaseOverlapFinder.DispatchOverlaps(threadDispatcher);
ProfilerEnd(BroadPhaseOverlapFinder);
ProfilerStart(NarrowPhase);
NarrowPhase.Flush(threadDispatcher, threadDispatcher != null && Deterministic);
ProfilerEnd(NarrowPhase);
ProfilerStart(Solver);
if (threadDispatcher == null)
{
Solver.Update(dt);
}
else
{
Solver.MultithreadedUpdate(threadDispatcher, BufferPool, dt);
}
ProfilerEnd(Solver);
//Note that constraint optimization should be performed after body optimization, since body optimization moves the bodies- and so affects the optimal constraint position.
//TODO: The order of these optimizer stages is performance relevant, even though they don't have any effect on correctness.
//You may want to try them in different locations to see how they impact cache residency.
ProfilerStart(BodyLayoutOptimizer);
if (threadDispatcher == null)
{
BodyLayoutOptimizer.IncrementalOptimize();
}
else
{
BodyLayoutOptimizer.IncrementalOptimize(BufferPool, threadDispatcher);
}
ProfilerEnd(BodyLayoutOptimizer);
ProfilerStart(ConstraintLayoutOptimizer);
ConstraintLayoutOptimizer.Update(BufferPool, threadDispatcher);
ProfilerEnd(ConstraintLayoutOptimizer);
ProfilerStart(SolverBatchCompressor);
SolverBatchCompressor.Compress(BufferPool, threadDispatcher, threadDispatcher != null && Deterministic);
ProfilerEnd(SolverBatchCompressor);
ProfilerEnd(this);
}