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

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
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@ -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);