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Apply old method for linear & angular damping in Bullet, in order to

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make it easier to tweak and consistent with Godot Physics.

Include patch applied to Bullet master to enable dampings greater than 1.
This commit is contained in:
Marcel Admiraal 2020-05-27 17:50:49 +01:00
parent 8f0f2bf4ef
commit 5d8b0649be
3 changed files with 46 additions and 6 deletions
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2
modules/bullet/SCsub
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@ -208,6 +208,8 @@ if env['builtin_bullet']:
# if env['target'] == "debug" or env['target'] == "release_debug":
# env_bullet.Append(CPPDEFINES=['BT_DEBUG'])
env_bullet.Append(CPPDEFINES=["BT_USE_OLD_DAMPING_METHOD"])
env_thirdparty = env_bullet.Clone()
env_thirdparty.disable_warnings()
env_thirdparty.add_source_files(env.modules_sources, thirdparty_sources)

34
thirdparty/bullet/0001-old-damping-def.patch vendored Normal file
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@ -0,0 +1,34 @@
diff --git a/thirdparty/bullet/BulletDynamics/Dynamics/btRigidBody.cpp b/thirdparty/bullet/BulletDynamics/Dynamics/btRigidBody.cpp
index 9e8705b001..f1b50b39c8 100644
--- a/thirdparty/bullet/BulletDynamics/Dynamics/btRigidBody.cpp
+++ b/thirdparty/bullet/BulletDynamics/Dynamics/btRigidBody.cpp
@@ -136,8 +136,13 @@ void btRigidBody::setGravity(const btVector3& acceleration)
void btRigidBody::setDamping(btScalar lin_damping, btScalar ang_damping)
{
- m_linearDamping = btClamped(lin_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
- m_angularDamping = btClamped(ang_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
+#ifdef BT_USE_OLD_DAMPING_METHOD
+ m_linearDamping = btMax(lin_damping, btScalar(0.0));
+ m_angularDamping = btMax(ang_damping, btScalar(0.0));
+#else
+ m_linearDamping = btClamped(lin_damping, btScalar(0.0), btScalar(1.0));
+ m_angularDamping = btClamped(ang_damping, btScalar(0.0), btScalar(1.0));
+#endif
}
///applyDamping damps the velocity, using the given m_linearDamping and m_angularDamping
@@ -146,10 +151,9 @@ void btRigidBody::applyDamping(btScalar timeStep)
//On new damping: see discussion/issue report here: http://code.google.com/p/bullet/issues/detail?id=74
//todo: do some performance comparisons (but other parts of the engine are probably bottleneck anyway
-//#define USE_OLD_DAMPING_METHOD 1
-#ifdef USE_OLD_DAMPING_METHOD
- m_linearVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_linearDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
- m_angularVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_angularDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
+#ifdef BT_USE_OLD_DAMPING_METHOD
+ m_linearVelocity *= btMax((btScalar(1.0) - timeStep * m_linearDamping), btScalar(0.0));
+ m_angularVelocity *= btMax((btScalar(1.0) - timeStep * m_angularDamping), btScalar(0.0));
#else
m_linearVelocity *= btPow(btScalar(1) - m_linearDamping, timeStep);
m_angularVelocity *= btPow(btScalar(1) - m_angularDamping, timeStep);

16
thirdparty/bullet/BulletDynamics/Dynamics/btRigidBody.cpp vendored
View file

@ -136,8 +136,13 @@ void btRigidBody::setGravity(const btVector3& acceleration)
void btRigidBody::setDamping(btScalar lin_damping, btScalar ang_damping)
{
m_linearDamping = btClamped(lin_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
m_angularDamping = btClamped(ang_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
#ifdef BT_USE_OLD_DAMPING_METHOD
m_linearDamping = btMax(lin_damping, btScalar(0.0));
m_angularDamping = btMax(ang_damping, btScalar(0.0));
#else
m_linearDamping = btClamped(lin_damping, btScalar(0.0), btScalar(1.0));
m_angularDamping = btClamped(ang_damping, btScalar(0.0), btScalar(1.0));
#endif
}
///applyDamping damps the velocity, using the given m_linearDamping and m_angularDamping
@ -146,10 +151,9 @@ void btRigidBody::applyDamping(btScalar timeStep)
//On new damping: see discussion/issue report here: http://code.google.com/p/bullet/issues/detail?id=74
//todo: do some performance comparisons (but other parts of the engine are probably bottleneck anyway
//#define USE_OLD_DAMPING_METHOD 1
#ifdef USE_OLD_DAMPING_METHOD
m_linearVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_linearDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
m_angularVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_angularDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
#ifdef BT_USE_OLD_DAMPING_METHOD
m_linearVelocity *= btMax((btScalar(1.0) - timeStep * m_linearDamping), btScalar(0.0));
m_angularVelocity *= btMax((btScalar(1.0) - timeStep * m_angularDamping), btScalar(0.0));
#else
m_linearVelocity *= btPow(btScalar(1) - m_linearDamping, timeStep);
m_angularVelocity *= btPow(btScalar(1) - m_angularDamping, timeStep);