Fix applied rotation from moving platforms in move_and_slide

When synchronizing CharacterBody motion with moving the platform using
direct body state, only the linear velocity was taken into account.

This change exposes velocity at local point in direct body state and
uses it in move_and_slide to get the proper velocity that includes
rotations.

2 files changed, 12 insertions, 0 deletions

diff --git a/modules/bullet/rigid_body_bullet.cpp b/modules/bullet/rigid_body_bullet.cpp
index ce39d4f0df..0d2cd1f5a0 100644
--- a/modules/bullet/rigid_body_bullet.cpp
+++ b/modules/bullet/rigid_body_bullet.cpp
@@ -114,6 +114,16 @@ Transform3D BulletPhysicsDirectBodyState3D::get_transform() const {
 	return body->get_transform();
 }
 
+Vector3 BulletPhysicsDirectBodyState3D::get_velocity_at_local_position(const Vector3 &p_position) const {
+	btVector3 local_position;
+	G_TO_B(p_position, local_position);
+
+	Vector3 velocity;
+	B_TO_G(body->btBody->getVelocityInLocalPoint(local_position), velocity);
+
+	return velocity;
+}
+
 void BulletPhysicsDirectBodyState3D::add_central_force(const Vector3 &p_force) {
 	body->apply_central_force(p_force);
 }
diff --git a/modules/bullet/rigid_body_bullet.h b/modules/bullet/rigid_body_bullet.h
index 606df7134b..5e102d8b05 100644
--- a/modules/bullet/rigid_body_bullet.h
+++ b/modules/bullet/rigid_body_bullet.h
@@ -110,6 +110,8 @@ public:
 	virtual void set_transform(const Transform3D &p_transform) override;
 	virtual Transform3D get_transform() const override;
 
+	virtual Vector3 get_velocity_at_local_position(const Vector3 &p_position) const override;
+
 	virtual void add_central_force(const Vector3 &p_force) override;
 	virtual void add_force(const Vector3 &p_force, const Vector3 &p_position = Vector3()) override;
 	virtual void add_torque(const Vector3 &p_torque) override;