public void Solve(ref TimeStep step, ref FVector2 gravity)
{
float h = step.dt;
// Integrate velocities and apply damping. Initialize the body state.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
FVector2 c = b.Sweep.C;
float a = b.Sweep.A;
FVector2 v = b.LinearVelocity;
float w = b.AngularVelocity;
// Store positions for continuous collision.
b.Sweep.C0 = b.Sweep.C;
b.Sweep.A0 = b.Sweep.A;
if (b.BodyType == BodyType.Dynamic)
{
// Integrate velocities.
v += h * (b.GravityScale * gravity + b.InvMass * b.Force);
w += h * b.InvI * b.Torque;
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
v *= MathUtils.Clamp(1.0f - h * b.LinearDamping, 0.0f, 1.0f);
w *= MathUtils.Clamp(1.0f - h * b.AngularDamping, 0.0f, 1.0f);
}
_positions[i].c = c;
_positions[i].a = a;
_velocities[i].v = v;
_velocities[i].w = w;
}
// Solver data
SolverData solverData = new SolverData();
solverData.step = step;
solverData.positions = _positions;
solverData.velocities = _velocities;
// Initialize velocity constraints.
//b2ContactSolverDef contactSolverDef;
//contactSolverDef.step = step;
//contactSolverDef.contacts = m_contacts;
//contactSolverDef.count = m_contactCount;
//contactSolverDef.positions = m_positions;
//contactSolverDef.velocities = m_velocities;
//contactSolverDef.allocator = m_allocator;
_contactSolver.Reset(step, ContactCount, _contacts, _positions, _velocities);
_contactSolver.InitializeVelocityConstraints();
if (Settings.EnableWarmstarting)
{
_contactSolver.WarmStart();
}
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_watch.Start();
_tmpTime = 0;
}
#endif
for (int i = 0; i < JointCount; ++i)
{
if (_joints[i].Enabled)
{
_joints[i].InitVelocityConstraints(ref solverData);
}
}
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_tmpTime += _watch.ElapsedTicks;
}
#endif
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
#endif
for (int j = 0; j < JointCount; ++j)
{
FarseerJoint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
joint.SolveVelocityConstraints(ref solverData);
//TODO: Move up before solve?
joint.Validate(step.inv_dt);
}
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_watch.Stop();
_tmpTime += _watch.ElapsedTicks;
_watch.Reset();
}
#endif
_contactSolver.SolveVelocityConstraints();
}
// Store impulses for warm starting.
_contactSolver.StoreImpulses();
// Integrate positions
for (int i = 0; i < BodyCount; ++i)
{
FVector2 c = _positions[i].c;
float a = _positions[i].a;
FVector2 v = _velocities[i].v;
float w = _velocities[i].w;
// Check for large velocities
FVector2 translation = h * v;
if (FVector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
_positions[i].c = c;
_positions[i].a = a;
_velocities[i].v = v;
_velocities[i].w = w;
}
// Solve position constraints
bool positionSolved = false;
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints();
bool jointsOkay = true;
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
#endif
for (int j = 0; j < JointCount; ++j)
{
FarseerJoint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
bool jointOkay = joint.SolvePositionConstraints(ref solverData);
jointsOkay = jointsOkay && jointOkay;
}
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
_watch.Stop();
_tmpTime += _watch.ElapsedTicks;
_watch.Reset();
}
#endif
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
positionSolved = true;
break;
}
}
#if (!SILVERLIGHT)
if (Settings.EnableDiagnostics)
{
JointUpdateTime = _tmpTime;
}
#endif
// Copy state buffers back to the bodies
for (int i = 0; i < BodyCount; ++i)
{
Body body = Bodies[i];
body.Sweep.C = _positions[i].c;
body.Sweep.A = _positions[i].a;
body.LinearVelocity = _velocities[i].v;
body.AngularVelocity = _velocities[i].w;
body.SynchronizeTransform();
}
Report(_contactSolver._velocityConstraints);
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0 ||
b.AngularVelocityInternal * b.AngularVelocityInternal > AngTolSqr ||
FVector2.Dot(b.LinearVelocityInternal, b.LinearVelocityInternal) > LinTolSqr)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b.SleepTime += h;
minSleepTime = Math.Min(minSleepTime, b.SleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep && positionSolved)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.Awake = false;
}
}
}
}
public void Solve(ref TimeStep step, ref Vector2 gravity)
{
float h = step.dt;
// Integrate velocities and apply damping. Initialize the body state.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
Vector2 c = b._sweep.C;
float a = b._sweep.A;
Vector2 v = b._linearVelocity;
float w = b._angularVelocity;
// Store positions for continuous collision.
b._sweep.C0 = b._sweep.C;
b._sweep.A0 = b._sweep.A;
// Added by Grimelios.
int decelerationSign = b.ManuallyControlled ? Math.Sign(v.X) : 0;
if (b.BodyType == BodyType.Dynamic)
{
// Integrate velocities.
// FPE: Only apply gravity if the body wants it.
if (b.IgnoreGravity)
{
v += h * (b._invMass * b._force);
}
else
{
v += h * (b.GravityScale * gravity + b._invMass * b._force);
}
w += h * b._invI * b._torque;
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
v *= MathUtils.Clamp(1.0f - h * b.LinearDamping, 0.0f, 1.0f);
w *= MathUtils.Clamp(1.0f - h * b.AngularDamping, 0.0f, 1.0f);
}
// Added by Grimelios.
bool accelerating = b.Accelerating;
bool decelerating = b.Decelerating;
// Acceleration and deceleration will never be set at the same time. However, both can be false, indicating that the player
// is fully stopped.
if (b.ManuallyControlled && (accelerating ^ decelerating))
{
if (b.Accelerating)
{
Vector2 maxSpeed = b.MaximumSpeed;
v.X = MathHelper.Clamp(v.X, -maxSpeed.X, maxSpeed.X);
v.Y = MathHelper.Clamp(v.Y, -maxSpeed.Y, maxSpeed.Y);
}
else if (b.Decelerating && decelerationSign != Math.Sign(v.X))
{
v.X = 0;
b.Decelerating = false;
}
}
_positions[i].c = c;
_positions[i].a = a;
_velocities[i].v = v;
_velocities[i].w = w;
}
// Solver data
SolverData solverData = new SolverData();
solverData.step = step;
solverData.positions = _positions;
solverData.velocities = _velocities;
_contactSolver.Reset(step, ContactCount, _contacts, _positions, _velocities);
_contactSolver.InitializeVelocityConstraints();
if (Settings.EnableWarmstarting)
{
_contactSolver.WarmStart();
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
for (int i = 0; i < JointCount; ++i)
{
if (_joints[i].Enabled)
{
_joints[i].InitVelocityConstraints(ref solverData);
}
}
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
joint.SolveVelocityConstraints(ref solverData);
joint.Validate(step.inv_dt);
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
}
_contactSolver.SolveVelocityConstraints();
}
// Store impulses for warm starting.
_contactSolver.StoreImpulses();
// Integrate positions
for (int i = 0; i < BodyCount; ++i)
{
Vector2 c = _positions[i].c;
float a = _positions[i].a;
Vector2 v = _velocities[i].v;
float w = _velocities[i].w;
// Check for large velocities
Vector2 translation = h * v;
if (Vector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
_positions[i].c = c;
_positions[i].a = a;
_velocities[i].v = v;
_velocities[i].w = w;
}
// Solve position constraints
bool positionSolved = false;
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints();
bool jointsOkay = true;
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
bool jointOkay = joint.SolvePositionConstraints(ref solverData);
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
positionSolved = true;
break;
}
}
if (Settings.EnableDiagnostics)
{
JointUpdateTime = _watch.ElapsedTicks;
_watch.Reset();
}
// Copy state buffers back to the bodies
for (int i = 0; i < BodyCount; ++i)
{
Body body = Bodies[i];
body._sweep.C = _positions[i].c;
body._sweep.A = _positions[i].a;
body._linearVelocity = _velocities[i].v;
body._angularVelocity = _velocities[i].w;
body.SynchronizeTransform();
}
Report(_contactSolver._velocityConstraints);
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if (!b.SleepingAllowed || b._angularVelocity * b._angularVelocity > AngTolSqr || Vector2.Dot(b._linearVelocity, b._linearVelocity) > LinTolSqr)
{
b._sleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b._sleepTime += h;
minSleepTime = Math.Min(minSleepTime, b._sleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep && positionSolved)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.Awake = false;
}
}
}
}
internal void SolveTOI(ref TimeStep subStep, int toiIndexA, int toiIndexB)
{
Debug.Assert(toiIndexA < BodyCount);
Debug.Assert(toiIndexB < BodyCount);
// Initialize the body state.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
_positions[i].c = b.Sweep.C;
_positions[i].a = b.Sweep.A;
_velocities[i].v = b.LinearVelocity;
_velocities[i].w = b.AngularVelocity;
}
//b2ContactSolverDef contactSolverDef;
//contactSolverDef.contacts = _contacts;
//contactSolverDef.count = _contactCount;
//contactSolverDef.allocator = _allocator;
//contactSolverDef.step = subStep;
//contactSolverDef.positions = _positions;
//contactSolverDef.velocities = _velocities;
//b2ContactSolver contactSolver(&contactSolverDef);
_contactSolver.Reset(subStep, ContactCount, _contacts, _positions, _velocities);
// Solve position constraints.
for (int i = 0; i < Settings.TOIPositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolveTOIPositionConstraints(toiIndexA, toiIndexB);
if (contactsOkay)
{
break;
}
}
// Leap of faith to new safe state.
Bodies[toiIndexA].Sweep.C0 = _positions[toiIndexA].c;
Bodies[toiIndexA].Sweep.A0 = _positions[toiIndexA].a;
Bodies[toiIndexB].Sweep.C0 = _positions[toiIndexB].c;
Bodies[toiIndexB].Sweep.A0 = _positions[toiIndexB].a;
// No warm starting is needed for TOI events because warm
// starting impulses were applied in the discrete solver.
_contactSolver.InitializeVelocityConstraints();
// Solve velocity constraints.
for (int i = 0; i < Settings.TOIVelocityIterations; ++i)
{
_contactSolver.SolveVelocityConstraints();
}
// Don't store the TOI contact forces for warm starting
// because they can be quite large.
float h = subStep.dt;
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
FVector2 c = _positions[i].c;
float a = _positions[i].a;
FVector2 v = _velocities[i].v;
float w = _velocities[i].w;
// Check for large velocities
FVector2 translation = h * v;
if (FVector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
_positions[i].c = c;
_positions[i].a = a;
_velocities[i].v = v;
_velocities[i].w = w;
// Sync bodies
Body body = Bodies[i];
body.Sweep.C = c;
body.Sweep.A = a;
body.LinearVelocity = v;
body.AngularVelocity = w;
body.SynchronizeTransform();
}
Report(_contactSolver._velocityConstraints);
}
internal void SolveTOI(ref TimeStep subStep)
{
_contactSolver.Reset(_contacts, ContactCount, subStep.dtRatio, false);
// Solve position constraints.
const float kTOIBaumgarte = 0.75f;
for (int i = 0; i < Settings.TOIPositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints(kTOIBaumgarte);
if (contactsOkay)
{
break;
}
if (i == Settings.TOIPositionIterations - 1)
{
i += 0;
}
}
// Leap of faith to new safe state.
for (int i = 0; i < BodyCount; ++i)
{
Body body = Bodies[i];
body.Sweep.A0 = body.Sweep.A;
body.Sweep.C0 = body.Sweep.C;
}
// No warm starting is needed for TOI events because warm
// starting impulses were applied in the discrete solver.
_contactSolver.InitializeVelocityConstraints();
// Solve velocity constraints.
for (int i = 0; i < Settings.TOIVelocityIterations; ++i)
{
_contactSolver.SolveVelocityConstraints();
}
// Don't store the TOI contact forces for warm starting
// because they can be quite large.
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
// Check for large velocities.
float translationx = subStep.dt * b.LinearVelocityInternal.X;
float translationy = subStep.dt * b.LinearVelocityInternal.Y;
float dot = translationx * translationx + translationy * translationy;
if (dot > Settings.MaxTranslationSquared)
{
float norm = 1f / (float)Math.Sqrt(dot);
float value = Settings.MaxTranslation * subStep.inv_dt;
b.LinearVelocityInternal.X = value * (translationx * norm);
b.LinearVelocityInternal.Y = value * (translationy * norm);
}
float rotation = subStep.dt * b.AngularVelocity;
if (rotation * rotation > Settings.MaxRotationSquared)
{
if (rotation < 0.0)
{
b.AngularVelocityInternal = -subStep.inv_dt * Settings.MaxRotation;
}
else
{
b.AngularVelocityInternal = subStep.inv_dt * Settings.MaxRotation;
}
}
// Integrate
b.Sweep.C.X += subStep.dt * b.LinearVelocityInternal.X;
b.Sweep.C.Y += subStep.dt * b.LinearVelocityInternal.Y;
b.Sweep.A += subStep.dt * b.AngularVelocityInternal;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
Report(_contactSolver.Constraints);
}
public void Solve(ref TimeStep step, ref Vector2 gravity)
{
// Integrate velocities and apply damping.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType != BodyType.Dynamic)
{
continue;
}
// Integrate velocities.
// FPE 3 only - Only apply gravity if the body wants it.
if (b.IgnoreGravity)
{
b.LinearVelocityInternal.X += step.dt * (b.InvMass * b.Force.X);
b.LinearVelocityInternal.Y += step.dt * (b.InvMass * b.Force.Y);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
else
{
b.LinearVelocityInternal.X += step.dt * (gravity.X + b.InvMass * b.Force.X);
b.LinearVelocityInternal.Y += step.dt * (gravity.Y + b.InvMass * b.Force.Y);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
b.LinearVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.LinearDamping, 0.0f, 1.0f);
b.AngularVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.AngularDamping, 0.0f, 1.0f);
}
// Partition contacts so that contacts with static bodies are solved last.
int i1 = -1;
for (int i2 = 0; i2 < ContactCount; ++i2)
{
Fixture fixtureA = _contacts[i2].FixtureA;
Fixture fixtureB = _contacts[i2].FixtureB;
Body bodyA = fixtureA.Body;
Body bodyB = fixtureB.Body;
bool nonStatic = bodyA.BodyType != BodyType.Static && bodyB.BodyType != BodyType.Static;
if (nonStatic)
{
++i1;
//TODO: Only swap if they are not the same? see http://code.google.com/p/box2d/issues/detail?id=162
Contact tmp = _contacts[i1];
_contacts[i1] = _contacts[i2];
_contacts[i2] = tmp;
}
}
// Initialize velocity constraints.
_contactSolver.Reset(_contacts, ContactCount, step.dtRatio, Settings.EnableWarmstarting);
_contactSolver.InitializeVelocityConstraints();
if (Settings.EnableWarmstarting)
{
_contactSolver.WarmStart();
}
for (int i = 0; i < JointCount; ++i)
{
if (_joints[i].Enabled)
{
_joints[i].InitVelocityConstraints(ref step);
}
}
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
joint.SolveVelocityConstraints(ref step);
joint.Validate(step.inv_dt);
}
_contactSolver.SolveVelocityConstraints();
}
// Post-solve (store impulses for warm starting).
_contactSolver.StoreImpulses();
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
// Check for large velocities.
float translationX = step.dt * b.LinearVelocityInternal.X;
float translationY = step.dt * b.LinearVelocityInternal.Y;
float result = translationX * translationX + translationY * translationY;
if (result > Settings.MaxTranslationSquared)
{
float sq = (float)Math.Sqrt(result);
float ratio = Settings.MaxTranslation / sq;
b.LinearVelocityInternal.X *= ratio;
b.LinearVelocityInternal.Y *= ratio;
}
float rotation = step.dt * b.AngularVelocityInternal;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / (float)Math.Abs(rotation);
b.AngularVelocityInternal *= ratio;
}
// Store positions for continuous collision.
b.Sweep.C0.X = b.Sweep.C.X;
b.Sweep.C0.Y = b.Sweep.C.Y;
b.Sweep.A0 = b.Sweep.A;
// Integrate
b.Sweep.C.X += step.dt * b.LinearVelocityInternal.X;
b.Sweep.C.Y += step.dt * b.LinearVelocityInternal.Y;
b.Sweep.A += step.dt * b.AngularVelocityInternal;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
// Iterate over constraints.
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints(Settings.ContactBaumgarte);
bool jointsOkay = true;
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
bool jointOkay = joint.SolvePositionConstraints();
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
break;
}
}
Report(_contactSolver.Constraints);
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0 ||
b.AngularVelocityInternal * b.AngularVelocityInternal > AngTolSqr ||
Vector2.Dot(b.LinearVelocityInternal, b.LinearVelocityInternal) > LinTolSqr)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b.SleepTime += step.dt;
minSleepTime = Math.Min(minSleepTime, b.SleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.Awake = false;
}
}
}
}
public void Solve(ref TimeStep step, ref System.Numerics.Vector2 gravity)
{
float h = step.Dt;
// Integrate velocities and apply damping. Initialize the body state.
for (int i = 0; i < BodyCount; ++i)
{
var b = Bodies[i];
var c = b._sweep.C;
float a = b._sweep.A;
var v = b._linearVelocity;
float w = b._angularVelocity;
// Store positions for continuous collision.
b._sweep.C0 = b._sweep.C;
b._sweep.A0 = b._sweep.A;
if (b.BodyType == BodyType.Dynamic)
{
// Integrate velocities.
// FPE: Only apply gravity if the body wants it.
if (b.IgnoreGravity)
{
v += h * (b._invMass * b._force);
}
else
{
v += h * (b.GravityScale * gravity + b._invMass * b._force);
}
w += h * b._invI * b._torque;
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
v *= MathUtils.Clamp(1.0f - h * b.LinearDamping, 0.0f, 1.0f);
w *= MathUtils.Clamp(1.0f - h * b.AngularDamping, 0.0f, 1.0f);
}
_positions[i].C = c;
_positions[i].A = a;
_velocities[i].V = v;
_velocities[i].W = w;
}
// Solver data
SolverData solverData = new SolverData();
solverData.Step = step;
solverData.Positions = _positions;
solverData.Velocities = _velocities;
_contactSolver.Reset(step, ContactCount, _contacts, _positions, _velocities);
_contactSolver.InitializeVelocityConstraints();
if (Settings.EnableWarmstarting)
{
_contactSolver.WarmStart();
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
for (int i = 0; i < JointCount; ++i)
{
if (_joints[i].Enabled)
{
_joints[i].InitVelocityConstraints(ref solverData);
}
}
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
joint.SolveVelocityConstraints(ref solverData);
joint.Validate(step.Inv_dt);
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
}
_contactSolver.SolveVelocityConstraints();
}
// Store impulses for warm starting.
_contactSolver.StoreImpulses();
// Integrate positions
for (int i = 0; i < BodyCount; ++i)
{
System.Numerics.Vector2 c = _positions[i].C;
float a = _positions[i].A;
System.Numerics.Vector2 v = _velocities[i].V;
float w = _velocities[i].W;
// Check for large velocities
System.Numerics.Vector2 translation = h * v;
if (System.Numerics.Vector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
_positions[i].C = c;
_positions[i].A = a;
_velocities[i].V = v;
_velocities[i].W = w;
}
// Solve position constraints
bool positionSolved = false;
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints();
bool jointsOkay = true;
for (int j = 0; j < JointCount; ++j)
{
Joint joint = _joints[j];
if (!joint.Enabled)
{
continue;
}
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
bool jointOkay = joint.SolvePositionConstraints(ref solverData);
if (Settings.EnableDiagnostics)
{
_watch.Stop();
}
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
positionSolved = true;
break;
}
}
if (Settings.EnableDiagnostics)
{
JointUpdateTime = _watch.ElapsedTicks;
_watch.Reset();
}
// Copy state buffers back to the bodies
for (int i = 0; i < BodyCount; ++i)
{
Body body = Bodies[i];
body._sweep.C = _positions[i].C;
body._sweep.A = _positions[i].A;
body._linearVelocity = _velocities[i].V;
body._angularVelocity = _velocities[i].W;
body.SynchronizeTransform();
}
Report(_contactSolver._velocityConstraints);
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if (!b.IsSleepingAllowed || b._angularVelocity * b._angularVelocity > AngTolSqr ||
System.Numerics.Vector2.Dot(b._linearVelocity, b._linearVelocity) > LinTolSqr)
{
b._sleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b._sleepTime += h;
minSleepTime = Math.Min(minSleepTime, b._sleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep && positionSolved)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.IsAwake = false;
}
}
}
}
/// <summary>
/// Find TOI contacts and solve them.
/// </summary>
/// <param name="step">The step.</param>
private void SolveTOI(ref TimeStep step)
{
this.Island.Reset(2 * Settings.MaxTOIContacts, Settings.MaxTOIContacts, 0, this.ContactManager);
if (this._stepComplete)
{
for (int i = 0; i < this.BodyList.Count; i++)
{
this.BodyList[i].Flags &= ~BodyFlags.Island;
this.BodyList[i].Sweep.Alpha0 = 0.0f;
}
for (int i = 0; i < this.ContactManager.ContactList.Count; i++)
{
Contact c = this.ContactManager.ContactList[i];
// Invalidate TOI
c.Flags &= ~(ContactFlags.TOI | ContactFlags.Island);
c.TOICount = 0;
c.TOI = 1.0f;
}
}
// Find TOI events and solve them.
for (; ;)
{
// Find the first TOI.
Contact minContact = null;
float minAlpha = 1.0f;
for (int i = 0; i < this.ContactManager.ContactList.Count; i++)
{
Contact c = this.ContactManager.ContactList[i];
// Is this contact disabled?
if (c.Enabled == false)
{
continue;
}
// Prevent excessive sub-stepping.
if (c.TOICount > Settings.MaxSubSteps)
{
continue;
}
float alpha;
if ((c.Flags & ContactFlags.TOI) == ContactFlags.TOI)
{
// This contact has a valid cached TOI.
alpha = c.TOI;
}
else
{
Fixture fA = c.FixtureA;
Fixture fB = c.FixtureB;
// Is there a sensor?
if (fA.IsSensor || fB.IsSensor)
{
continue;
}
Body bA = fA.Body;
Body bB = fB.Body;
BodyType typeA = bA.BodyType;
BodyType typeB = bB.BodyType;
Debug.Assert(typeA == BodyType.Dynamic || typeB == BodyType.Dynamic);
bool awakeA = bA.Awake && typeA != BodyType.Static;
bool awakeB = bB.Awake && typeB != BodyType.Static;
// Is at least one body awake?
if (awakeA == false && awakeB == false)
{
continue;
}
bool collideA = (bA.IsBullet || typeA != BodyType.Dynamic) && !bA.IgnoreCCD;
bool collideB = (bB.IsBullet || typeB != BodyType.Dynamic) && !bB.IgnoreCCD;
// Are these two non-bullet dynamic bodies?
if (collideA == false && collideB == false)
{
continue;
}
// Compute the TOI for this contact.
// Put the sweeps onto the same time interval.
float alpha0 = bA.Sweep.Alpha0;
if (bA.Sweep.Alpha0 < bB.Sweep.Alpha0)
{
alpha0 = bB.Sweep.Alpha0;
bA.Sweep.Advance(alpha0);
}
else if (bB.Sweep.Alpha0 < bA.Sweep.Alpha0)
{
alpha0 = bA.Sweep.Alpha0;
bB.Sweep.Advance(alpha0);
}
Debug.Assert(alpha0 < 1.0f);
// Compute the time of impact in interval [0, minTOI]
this._input.ProxyA.Set(fA.Shape, c.ChildIndexA);
this._input.ProxyB.Set(fB.Shape, c.ChildIndexB);
this._input.SweepA = bA.Sweep;
this._input.SweepB = bB.Sweep;
this._input.TMax = 1.0f;
TOIOutput output;
TimeOfImpact.CalculateTimeOfImpact(out output, this._input);
// Beta is the fraction of the remaining portion of the .
float beta = output.T;
if (output.State == TOIOutputState.Touching)
{
alpha = Math.Min(alpha0 + (1.0f - alpha0) * beta, 1.0f);
}
else
{
alpha = 1.0f;
}
c.TOI = alpha;
c.Flags |= ContactFlags.TOI;
}
if (alpha < minAlpha)
{
// This is the minimum TOI found so far.
minContact = c;
minAlpha = alpha;
}
}
if (minContact == null || 1.0f - 10.0f * Settings.Epsilon < minAlpha)
{
// No more TOI events. Done!
this._stepComplete = true;
break;
}
// Advance the bodies to the TOI.
Fixture fA1 = minContact.FixtureA;
Fixture fB1 = minContact.FixtureB;
Body bA1 = fA1.Body;
Body bB1 = fB1.Body;
Sweep backup1 = bA1.Sweep;
Sweep backup2 = bB1.Sweep;
bA1.Advance(minAlpha);
bB1.Advance(minAlpha);
// The TOI contact likely has some new contact points.
minContact.Update(this.ContactManager);
minContact.Flags &= ~ContactFlags.TOI;
++minContact.TOICount;
// Is the contact solid?
if (minContact.Enabled == false || minContact.IsTouching() == false)
{
// Restore the sweeps.
minContact.Enabled = false;
bA1.Sweep = backup1;
bB1.Sweep = backup2;
bA1.SynchronizeTransform();
bB1.SynchronizeTransform();
continue;
}
bA1.Awake = true;
bB1.Awake = true;
// Build the island
this.Island.Clear();
this.Island.Add(bA1);
this.Island.Add(bB1);
this.Island.Add(minContact);
bA1.Flags |= BodyFlags.Island;
bB1.Flags |= BodyFlags.Island;
minContact.Flags |= ContactFlags.Island;
// Get contacts on bodyA and bodyB.
Body[] bodies = { bA1, bB1 };
for (int i = 0; i < 2; ++i)
{
Body body = bodies[i];
if (body.BodyType == BodyType.Dynamic)
{
// for (ContactEdge ce = body.ContactList; ce && Island.BodyCount < Settings.MaxTOIContacts; ce = ce.Next)
for (ContactEdge ce = body.ContactList; ce != null; ce = ce.Next)
{
Contact contact = ce.Contact;
// Has this contact already been added to the island?
if ((contact.Flags & ContactFlags.Island) == ContactFlags.Island)
{
continue;
}
// Only add static, kinematic, or bullet bodies.
Body other = ce.Other;
if (other.BodyType == BodyType.Dynamic &&
body.IsBullet == false && other.IsBullet == false)
{
continue;
}
// Skip sensors.
if (contact.FixtureA.IsSensor || contact.FixtureB.IsSensor)
{
continue;
}
// Tentatively advance the body to the TOI.
Sweep backup = other.Sweep;
if ((other.Flags & BodyFlags.Island) == 0)
{
other.Advance(minAlpha);
}
// Update the contact points
contact.Update(this.ContactManager);
// Was the contact disabled by the user?
if (contact.Enabled == false)
{
other.Sweep = backup;
other.SynchronizeTransform();
continue;
}
// Are there contact points?
if (contact.IsTouching() == false)
{
other.Sweep = backup;
other.SynchronizeTransform();
continue;
}
// Add the contact to the island
contact.Flags |= ContactFlags.Island;
this.Island.Add(contact);
// Has the other body already been added to the island?
if ((other.Flags & BodyFlags.Island) == BodyFlags.Island)
{
continue;
}
// Add the other body to the island.
other.Flags |= BodyFlags.Island;
if (other.BodyType != BodyType.Static)
{
other.Awake = true;
}
this.Island.Add(other);
}
}
}
TimeStep subStep;
subStep.dt = (1.0f - minAlpha) * step.dt;
subStep.inv_dt = 1.0f / subStep.dt;
subStep.dtRatio = 1.0f;
//subStep.positionIterations = 20;
//subStep.velocityIterations = step.velocityIterations;
//subStep.warmStarting = false;
this.Island.SolveTOI(ref subStep);
// Reset island flags and synchronize broad-phase proxies.
for (int i = 0; i < this.Island.BodyCount; ++i)
{
Body body = this.Island.Bodies[i];
body.Flags &= ~BodyFlags.Island;
if (body.BodyType != BodyType.Dynamic)
{
continue;
}
body.SynchronizeFixtures();
// Invalidate all contact TOIs on this displaced body.
for (ContactEdge ce = body.ContactList; ce != null; ce = ce.Next)
{
ce.Contact.Flags &= ~(ContactFlags.TOI | ContactFlags.Island);
}
}
// Commit fixture proxy movements to the broad-phase so that new contacts are created.
// Also, some contacts can be destroyed.
this.ContactManager.FindNewContacts();
if (this.EnableSubStepping)
{
this._stepComplete = false;
break;
}
}
}
internal void SolveTOI(ref TimeStep subStep, int toiIndexA, int toiIndexB)
{
Debug.Assert(toiIndexA < BodyCount);
Debug.Assert(toiIndexB < BodyCount);
// Initialize the body state.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
_positions[i].C = b._sweep.C;
_positions[i].A = b._sweep.A;
_velocities[i].V = b._linearVelocity;
_velocities[i].W = b._angularVelocity;
}
_contactSolver.Reset(subStep, ContactCount, _contacts, _positions, _velocities);
// Solve position constraints.
for (int i = 0; i < Settings.ToiPositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolveTOIPositionConstraints(toiIndexA, toiIndexB);
if (contactsOkay)
{
break;
}
}
// Leap of faith to new safe state.
Bodies[toiIndexA]._sweep.C0 = _positions[toiIndexA].C;
Bodies[toiIndexA]._sweep.A0 = _positions[toiIndexA].A;
Bodies[toiIndexB]._sweep.C0 = _positions[toiIndexB].C;
Bodies[toiIndexB]._sweep.A0 = _positions[toiIndexB].A;
// No warm starting is needed for TOI events because warm
// starting impulses were applied in the discrete solver.
_contactSolver.InitializeVelocityConstraints();
// Solve velocity constraints.
for (int i = 0; i < Settings.ToiVelocityIterations; ++i)
{
_contactSolver.SolveVelocityConstraints();
}
// Don't store the TOI contact forces for warm starting
// because they can be quite large.
float h = subStep.Dt;
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
System.Numerics.Vector2 c = _positions[i].C;
float a = _positions[i].A;
System.Numerics.Vector2 v = _velocities[i].V;
float w = _velocities[i].W;
// Check for large velocities
System.Numerics.Vector2 translation = h * v;
if (System.Numerics.Vector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
_positions[i].C = c;
_positions[i].A = a;
_velocities[i].V = v;
_velocities[i].W = w;
// Sync bodies
Body body = Bodies[i];
body._sweep.C = c;
body._sweep.A = a;
body._linearVelocity = v;
body._angularVelocity = w;
body.SynchronizeTransform();
}
Report(_contactSolver._velocityConstraints);
}
public void Solve(ref TimeStep step, Vector2 gravity)
{
// Integrate velocities and apply damping.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType != BodyType.Dynamic)
{
continue;
}
// Integrate velocities. Only apply gravity if the body wants it.
if (b.IgnoreGravity)
{
b.LinearVelocityInternal += step.dt * (b.InvMass * b.Force);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
else
{
b.LinearVelocityInternal += step.dt * (gravity + b.InvMass * b.Force);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
b.LinearVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.LinearDamping, 0.0f, 1.0f);
b.AngularVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.AngularDamping, 0.0f, 1.0f);
}
// Partition contacts so that contacts with static bodies are solved last.
int i1 = -1;
for (int i2 = 0; i2 < ContactCount; ++i2)
{
Fixture fixtureA = _contacts[i2].FixtureA;
Fixture fixtureB = _contacts[i2].FixtureB;
Body bodyA = fixtureA.Body;
Body bodyB = fixtureB.Body;
bool nonStatic = bodyA.BodyType != BodyType.Static && bodyB.BodyType != BodyType.Static;
if (nonStatic)
{
++i1;
// b2Swap(_contacts[i1], _contacts[i2]);
Contact temp = _contacts[i1];
_contacts[i1] = _contacts[i2];
_contacts[i2] = temp;
}
}
// Initialize velocity constraints.
_contactSolver.Reset(_contacts, ContactCount, step.dtRatio);
_contactSolver.WarmStart();
for (int i = 0; i < JointCount; ++i)
{
_joints[i].InitVelocityConstraints(ref step);
}
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
for (int j = 0; j < JointCount; ++j)
{
_joints[j].SolveVelocityConstraints(ref step);
}
_contactSolver.SolveVelocityConstraints();
}
// Post-solve (store impulses for warm starting).
_contactSolver.StoreImpulses();
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
// Check for large velocities.
Vector2 translation = step.dt * b.LinearVelocityInternal;
if (Vector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
b.LinearVelocityInternal *= ratio;
}
float rotation = step.dt * b.AngularVelocityInternal;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
b.AngularVelocityInternal *= ratio;
}
// Store positions for continuous collision.
b.Sweep.c0 = b.Sweep.c;
b.Sweep.a0 = b.Sweep.a;
// Integrate
b.Sweep.c += step.dt * b.LinearVelocityInternal;
b.Sweep.a += step.dt * b.AngularVelocityInternal;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
// Iterate over constraints.
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints(Settings.ContactBaumgarte);
bool jointsOkay = true;
for (int j = 0; j < JointCount; ++j)
{
bool jointOkay = _joints[j].SolvePositionConstraints();
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
break;
}
}
if (_contactManager.PostSolve != null)
{
Report(_contactSolver.Constraints);
}
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
const float linTolSqr = Settings.LinearSleepTolerance * Settings.LinearSleepTolerance;
const float angTolSqr = Settings.AngularSleepTolerance * Settings.AngularSleepTolerance;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0 ||
b.AngularVelocityInternal * b.AngularVelocityInternal > angTolSqr ||
Vector2.Dot(b.LinearVelocityInternal, b.LinearVelocityInternal) > linTolSqr)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b.SleepTime += step.dt;
minSleepTime = Math.Min(minSleepTime, b.SleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.Awake = false;
}
}
}
}
public void Solve(ref TimeStep step, ref Vector2 gravity)
{
// Integrate velocities and apply damping.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType != BodyType.Dynamic)
{
continue;
}
// Integrate velocities.
// FPE 3 only - Only apply gravity if the body wants it.
if (b.IgnoreGravity)
{
b.LinearVelocityInternal += step.dt * (b.InvMass * b.Force);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
else
{
b.LinearVelocityInternal += step.dt * (gravity + b.InvMass * b.Force);
b.AngularVelocityInternal += step.dt * b.InvI * b.Torque;
}
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
b.LinearVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.LinearDamping, 0.0f, 1.0f);
b.AngularVelocityInternal *= MathUtils.Clamp(1.0f - step.dt * b.AngularDamping, 0.0f, 1.0f);
}
// Partition contacts so that contacts with static bodies are solved last.
int i1 = -1;
for (int i2 = 0; i2 < ContactCount; ++i2)
{
Fixture fixtureA = _contacts[i2].FixtureA;
Fixture fixtureB = _contacts[i2].FixtureB;
Body bodyA = fixtureA.Body;
Body bodyB = fixtureB.Body;
bool nonStatic = bodyA.BodyType != BodyType.Static && bodyB.BodyType != BodyType.Static;
if (nonStatic)
{
++i1;
//TODO: Only swap if they are not the same? see http://code.google.com/p/box2d/issues/detail?id=162
//if (i1 != i2)
MathUtils.Swap(ref _contacts[i1], ref _contacts[i2]);
//Contact temp = _contacts[i1];
//_contacts[i1] = _contacts[i2];
//_contacts[i2] = temp;
}
}
// Initialize velocity constraints.
_contactSolver.Reset(_contacts, ContactCount, step.dtRatio);
_contactSolver.InitializeVelocityConstraints();
if (Settings.EnableWarmstarting)
{
_contactSolver.WarmStart();
}
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_watch.Start();
_tmpTime = 0;
}
#endif
for (int i = 0; i < JointCount; ++i)
{
_joints[i].InitVelocityConstraints(ref step);
}
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_tmpTime += _watch.ElapsedTicks;
}
#endif
// Solve velocity constraints.
for (int i = 0; i < Settings.VelocityIterations; ++i)
{
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
#endif
for (int j = 0; j < JointCount; ++j)
{
_joints[j].SolveVelocityConstraints(ref step);
}
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_watch.Stop();
_tmpTime += _watch.ElapsedTicks;
_watch.Reset();
}
#endif
_contactSolver.SolveVelocityConstraints();
}
// Post-solve (store impulses for warm starting).
_contactSolver.StoreImpulses();
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
// Check for large velocities.
Vector2 translation = step.dt * b.LinearVelocityInternal;
float result;
Vector2.Dot(ref translation, ref translation, out result);
if (result > Settings.MaxTranslationSquared)
{
float ratio = Settings.MaxTranslation / translation.Length();
b.LinearVelocityInternal *= ratio;
}
float rotation = step.dt * b.AngularVelocityInternal;
if (rotation * rotation > Settings.MaxRotationSquared)
{
float ratio = Settings.MaxRotation / Math.Abs(rotation);
b.AngularVelocityInternal *= ratio;
}
// Store positions for continuous collision.
b.Sweep.C0 = b.Sweep.C;
b.Sweep.A0 = b.Sweep.A;
// Integrate
b.Sweep.C += step.dt * b.LinearVelocityInternal;
b.Sweep.A += step.dt * b.AngularVelocityInternal;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
// Iterate over constraints.
for (int i = 0; i < Settings.PositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints(Settings.ContactBaumgarte);
bool jointsOkay = true;
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_watch.Start();
}
#endif
for (int j = 0; j < JointCount; ++j)
{
bool jointOkay = _joints[j].SolvePositionConstraints();
jointsOkay = jointsOkay && jointOkay;
}
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
_watch.Stop();
_tmpTime += _watch.ElapsedTicks;
_watch.Reset();
}
#endif
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
break;
}
}
#if (!SILVERLIGHT && !WINDOWS_PHONE)
if (Settings.EnableDiagnostics)
{
JointUpdateTime = _tmpTime;
}
#endif
if (_contactManager.PostSolve != null)
{
Report(_contactSolver.Constraints);
}
if (Settings.AllowSleep)
{
float minSleepTime = Settings.MaxFloat;
const float linTolSqr = Settings.LinearSleepTolerance * Settings.LinearSleepTolerance;
const float angTolSqr = Settings.AngularSleepTolerance * Settings.AngularSleepTolerance;
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
if ((b.Flags & BodyFlags.AutoSleep) == 0 ||
b.AngularVelocityInternal * b.AngularVelocityInternal > angTolSqr ||
Vector2.Dot(b.LinearVelocityInternal, b.LinearVelocityInternal) > linTolSqr)
{
b.SleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b.SleepTime += step.dt;
minSleepTime = Math.Min(minSleepTime, b.SleepTime);
}
}
if (minSleepTime >= Settings.TimeToSleep)
{
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
b.Awake = false;
}
}
}
}
internal void SolveTOI(ref TimeStep subStep, Body bodyA, Body bodyB)
{
_contactSolver.Reset(_contacts, ContactCount, subStep.dtRatio);
// Solve position constraints.
const float kTOIBaumgarte = 0.75f;
for (int i = 0; i < Settings.TOIPositionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraintsTOI(kTOIBaumgarte, bodyA, bodyB);
if (contactsOkay)
{
break;
}
if (i == Settings.TOIPositionIterations - 1)
{
i += 0;
}
}
/*
#if 0
* // Is the new position really safe?
* for (int32 i = 0; i < m_contactCount; ++i)
* {
* b2Contact* c = m_contacts[i];
* b2Fixture* fA = c->GetFixtureA();
* b2Fixture* fB = c->GetFixtureB();
*
* b2Body* bA = fA->GetBody();
* b2Body* bB = fB->GetBody();
*
* int32 indexA = c->GetChildIndexA();
* int32 indexB = c->GetChildIndexB();
*
* b2DistanceInput input;
* input.proxyA.Set(fA->GetShape(), indexA);
* input.proxyB.Set(fB->GetShape(), indexB);
* input.transformA = bA->GetTransform();
* input.transformB = bB->GetTransform();
* input.useRadii = false;
*
* b2DistanceOutput output;
* b2SimplexCache cache;
* cache.count = 0;
* b2Distance(&output, &cache, &input);
*
* if (output.distance == 0 || cache.count == 3)
* {
* cache.count += 0;
* }
* }
#endif
*/
// Leap of faith to new safe state.
for (int i = 0; i < BodyCount; ++i)
{
Bodies[i].Sweep.A0 = Bodies[i].Sweep.A;
Bodies[i].Sweep.C0 = Bodies[i].Sweep.C;
}
// No warm starting is needed for TOI events because warm
// starting impulses were applied in the discrete solver.
_contactSolver.InitializeVelocityConstraints();
// Solve velocity constraints.
for (int i = 0; i < Settings.TOIVelocityIterations; ++i)
{
_contactSolver.SolveVelocityConstraints();
}
// Don't store the TOI contact forces for warm starting
// because they can be quite large.
// Integrate positions.
for (int i = 0; i < BodyCount; ++i)
{
Body b = Bodies[i];
if (b.BodyType == BodyType.Static)
{
continue;
}
// Check for large velocities.
Vector2 translation = subStep.dt * b.LinearVelocity;
if (Vector2.Dot(translation, translation) > Settings.MaxTranslationSquared)
{
translation.Normalize();
b.LinearVelocity = (Settings.MaxTranslation * subStep.inv_dt) * translation;
}
float rotation = subStep.dt * b.AngularVelocity;
if (rotation * rotation > Settings.MaxRotationSquared)
{
if (rotation < 0.0)
{
b.AngularVelocity = -subStep.inv_dt * Settings.MaxRotation;
}
else
{
b.AngularVelocity = subStep.inv_dt * Settings.MaxRotation;
}
}
// Integrate
b.Sweep.C += subStep.dt * b.LinearVelocity;
b.Sweep.A += subStep.dt * b.AngularVelocity;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
if (_contactManager.PostSolve != null)
{
Report(_contactSolver.Constraints);
}
}
internal override bool SolvePositionConstraints(float baumgarte)
{
Body b1 = _body1;
Body b2 = _body2;
Vector2 s1 = _ground.GetXForm().Position + _groundAnchor1;
Vector2 s2 = _ground.GetXForm().Position + _groundAnchor2;
float linearError = 0.0f;
if (_state == LimitState.AtUpperLimit)
{
Vector2 r1 = CommonMath.Mul(b1.GetXForm().R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = CommonMath.Mul(b2.GetXForm().R, _localAnchor2 - b2.GetLocalCenter());
Vector2 p1 = b1._sweep.C + r1;
Vector2 p2 = b2._sweep.C + r2;
// Get the pulley axes.
_u1 = p1 - s1;
_u2 = p2 - s2;
float length1 = _u1.Length();
float length2 = _u2.Length();
if (length1 > Settings.LinearSlop)
{
_u1 *= 1.0f / length1;
}
else
{
_u1 = Vector2.Zero;
}
if (length2 > Settings.LinearSlop)
{
_u2 *= 1.0f / length2;
}
else
{
_u2 = Vector2.Zero;
}
float C = _constant - length1 - _ratio * length2;
linearError = CommonMath.Max(linearError, -C);
C = CommonMath.Clamp(C + Settings.LinearSlop, -Settings.MaxLinearCorrection, 0.0f);
float impulse = -_pulleyMass * C;
Vector2 P1 = -impulse * _u1;
Vector2 P2 = -_ratio * impulse * _u2;
b1._sweep.C += b1._invMass * P1;
b1._sweep.A += b1._invI * CommonMath.Cross(ref r1, ref P1);
b2._sweep.C += b2._invMass * P2;
b2._sweep.A += b2._invI * CommonMath.Cross(ref r2, ref P2);
b1.SynchronizeTransform();
b2.SynchronizeTransform();
}
if (_limitState1 == LimitState.AtUpperLimit)
{
Vector2 r1 = CommonMath.Mul(b1.GetXForm().R, _localAnchor1 - b1.GetLocalCenter());
Vector2 p1 = b1._sweep.C + r1;
_u1 = p1 - s1;
float length1 = _u1.Length();
if (length1 > Settings.LinearSlop)
{
_u1 *= 1.0f / length1;
}
else
{
_u1 = Vector2.Zero;
}
float C = _maxLength1 - length1;
linearError = CommonMath.Max(linearError, -C);
C = CommonMath.Clamp(C + Settings.LinearSlop, -Settings.MaxLinearCorrection, 0.0f);
float impulse = -_limitMass1 * C;
Vector2 P1 = -impulse * _u1;
b1._sweep.C += b1._invMass * P1;
b1._sweep.A += b1._invI * CommonMath.Cross(ref r1, ref P1);
b1.SynchronizeTransform();
}
if (_limitState2 == LimitState.AtUpperLimit)
{
Vector2 r2 = CommonMath.Mul(b2.GetXForm().R, _localAnchor2 - b2.GetLocalCenter());
Vector2 p2 = b2._sweep.C + r2;
_u2 = p2 - s2;
float length2 = _u2.Length();
if (length2 > Settings.LinearSlop)
{
_u2 *= 1.0f / length2;
}
else
{
_u2 = Vector2.Zero;
}
float C = _maxLength2 - length2;
linearError = CommonMath.Max(linearError, -C);
C = CommonMath.Clamp(C + Settings.LinearSlop, -Settings.MaxLinearCorrection, 0.0f);
float impulse = -_limitMass2 * C;
Vector2 P2 = -impulse * _u2;
b2._sweep.C += b2._invMass * P2;
b2._sweep.A += b2._invI * CommonMath.Cross(ref r2, ref P2);
b2.SynchronizeTransform();
}
return(linearError < Settings.LinearSlop);
}
