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Implementing a simple velocity clamping to reduce floating point errors

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This commit is contained in:
Ellie
2020-03-13 18:53:42 +01:00
parent 830f0a9565
commit 78602fe656
4 changed files with 59 additions and 1 deletions
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5
CMakeLists.txt
View File

@@ -24,6 +24,7 @@ SET(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -D_DEBUG")
#MESSAGE("CMAKE_CXX_FLAGS_DEBUG="+${CMAKE_CXX_FLAGS_DEBUG})
OPTION(USE_DOUBLE_PRECISION "Use double precision" OFF)
SET(CLAMP_VELOCITIES "0" CACHE STRING "Clamp rigid bodies' velocity to this value, if larger than zero. Useful to prevent floating point errors or in general runaway velocities in complex scenarios")
OPTION(USE_GRAPHICAL_BENCHMARK "Use Graphical Benchmark" ON)
OPTION(BUILD_SHARED_LIBS "Use shared libraries" OFF)
OPTION(USE_SOFT_BODY_MULTI_BODY_DYNAMICS_WORLD "Use btSoftMultiBodyDynamicsWorld" ON)
@@ -212,6 +213,10 @@ IF (INTERNAL_UPDATE_SERIALIZATION_STRUCTURES)
ADD_DEFINITIONS( -DBT_INTERNAL_UPDATE_SERIALIZATION_STRUCTURES)
ENDIF (INTERNAL_UPDATE_SERIALIZATION_STRUCTURES)
IF (CLAMP_VELOCITIES)
ADD_DEFINITIONS( -DBT_CLAMP_VELOCITY_TO=${CLAMP_VELOCITIES})
ENDIF (CLAMP_VELOCITIES)
IF (USE_DOUBLE_PRECISION)
ADD_DEFINITIONS( -DBT_USE_DOUBLE_PRECISION)
SET( BULLET_DOUBLE_DEF "-DBT_USE_DOUBLE_PRECISION")

9
build3/premake4.lua
View File

@@ -337,6 +337,12 @@ end
trigger = "double",
description = "Double precision version of Bullet"
}
newoption
{
trigger = "clamp-velocities",
description = "Limit maximum velocities to reduce FP exception risk"
}
newoption
{
@@ -360,6 +366,9 @@ end
if _OPTIONS["double"] then
defines {"BT_USE_DOUBLE_PRECISION"}
end
if _OPTIONS["clamp-velocities"] then
defines {"BT_CLAMP_VELOCITY_TO=9999"}
end
configurations {"Release", "Debug"}
configuration "Release"

3
src/BulletDynamics/Dynamics/btRigidBody.cpp
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@@ -380,6 +380,9 @@ void btRigidBody::integrateVelocities(btScalar step)
{
m_angularVelocity *= (MAX_ANGVEL / step) / angvel;
}
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_angularVelocity);
#endif
}
btQuaternion btRigidBody::getOrientation() const

43
src/BulletDynamics/Dynamics/btRigidBody.h
View File

@@ -305,6 +305,9 @@ public:
void applyTorque(const btVector3& torque)
{
m_totalTorque += torque * m_angularFactor;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_totalTorque);
#endif
}
void applyForce(const btVector3& force, const btVector3& rel_pos)
@@ -316,11 +319,17 @@ public:
void applyCentralImpulse(const btVector3& impulse)
{
m_linearVelocity += impulse * m_linearFactor * m_inverseMass;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_linearVelocity);
#endif
}
void applyTorqueImpulse(const btVector3& torque)
{
m_angularVelocity += m_invInertiaTensorWorld * torque * m_angularFactor;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_angularVelocity);
#endif
}
void applyImpulse(const btVector3& impulse, const btVector3& rel_pos)
@@ -361,20 +370,46 @@ public:
{
m_pushVelocity = v;
}
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
void clampVelocity(btVector3& v) const {
v.setX(
fmax(-BT_CLAMP_VELOCITY_TO,
fmin(BT_CLAMP_VELOCITY_TO, v.getX()))
);
v.setY(
fmax(-BT_CLAMP_VELOCITY_TO,
fmin(BT_CLAMP_VELOCITY_TO, v.getY()))
);
v.setZ(
fmax(-BT_CLAMP_VELOCITY_TO,
fmin(BT_CLAMP_VELOCITY_TO, v.getZ()))
);
}
#endif
void setTurnVelocity(const btVector3& v)
{
m_turnVelocity = v;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_turnVelocity);
#endif
}
void applyCentralPushImpulse(const btVector3& impulse)
{
m_pushVelocity += impulse * m_linearFactor * m_inverseMass;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_pushVelocity);
#endif
}
void applyTorqueTurnImpulse(const btVector3& torque)
{
m_turnVelocity += m_invInertiaTensorWorld * torque * m_angularFactor;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_turnVelocity);
#endif
}
void clearForces()
@@ -408,12 +443,18 @@ public:
{
m_updateRevision++;
m_linearVelocity = lin_vel;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_linearVelocity);
#endif
}
inline void setAngularVelocity(const btVector3& ang_vel)
{
m_updateRevision++;
m_angularVelocity = ang_vel;
#if defined(BT_CLAMP_VELOCITY_TO) && BT_CLAMP_VELOCITY_TO > 0
clampVelocity(m_angularVelocity);
#endif
}
btVector3 getVelocityInLocalPoint(const btVector3& rel_pos) const