Merge pull request #11249 from m4nu3lf/bugfix/get_euler

Fix inertia tensor update & Generic6DOFJoint & Simplify Basis::get_euler()

core/math/matrix3.cpp

@@ -279,7 +279,7 @@ Vector3 Basis::get_signed_scale() const {
 
 // Decomposes a Basis into a rotation-reflection matrix (an element of the group O(3)) and a positive scaling matrix as B = O.S.
 // Returns the rotation-reflection matrix via reference argument, and scaling information is returned as a Vector3.
-// This (internal) function is too specıfıc and named too ugly to expose to users, and probably there's no need to do so.
+// This (internal) function is too specific and named too ugly to expose to users, and probably there's no need to do so.
 Vector3 Basis::rotref_posscale_decomposition(Basis &rotref) const {
 #ifdef MATH_CHECKS
 	ERR_FAIL_COND_V(determinant() == 0, Vector3());
@@ -371,31 +371,30 @@ Vector3 Basis::get_euler_xyz() const {
 #ifdef MATH_CHECKS
 	ERR_FAIL_COND_V(is_rotation() == false, euler);
 #endif
-	euler.y = Math::asin(elements[0][2]);
-	if (euler.y < Math_PI * 0.5) {
-		if (euler.y > -Math_PI * 0.5) {
+	real_t sy = elements[0][2];
+	if (sy < 1.0) {
+		if (sy > -1.0) {
 			// is this a pure Y rotation?
 			if (elements[1][0] == 0.0 && elements[0][1] == 0.0 && elements[1][2] == 0 && elements[2][1] == 0 && elements[1][1] == 1) {
-				// return the simplest form
+				// return the simplest form (human friendlier in editor and scripts)
 				euler.x = 0;
 				euler.y = atan2(elements[0][2], elements[0][0]);
 				euler.z = 0;
 			} else {
 				euler.x = Math::atan2(-elements[1][2], elements[2][2]);
+				euler.y = Math::asin(sy);
 				euler.z = Math::atan2(-elements[0][1], elements[0][0]);
 			}
-
 		} else {
-			real_t r = Math::atan2(elements[1][0], elements[1][1]);
+			euler.x = -Math::atan2(elements[0][1], elements[1][1]);
+			euler.y = -Math_PI / 2.0;
 			euler.z = 0.0;
-			euler.x = euler.z - r;
 		}
 	} else {
-		real_t r = Math::atan2(elements[0][1], elements[1][1]);
-		euler.z = 0;
-		euler.x = r - euler.z;
+		euler.x = Math::atan2(elements[0][1], elements[1][1]);
+		euler.y = Math_PI / 2.0;
+		euler.z = 0.0;
 	}
-
 	return euler;
 }
 
@@ -445,7 +444,7 @@ Vector3 Basis::get_euler_yxz() const {
 		if (m12 > -1) {
 			// is this a pure X rotation?
 			if (elements[1][0] == 0 && elements[0][1] == 0 && elements[0][2] == 0 && elements[2][0] == 0 && elements[0][0] == 1) {
-				// return the simplest form
+				// return the simplest form (human friendlier in editor and scripts)
 				euler.x = atan2(-m12, elements[1][1]);
 				euler.y = 0;
 				euler.z = 0;

servers/physics/body_sw.cpp

@@ -45,8 +45,9 @@ void BodySW::_update_transform_dependant() {
 	// update inertia tensor
 	Basis tb = principal_inertia_axes;
 	Basis tbt = tb.transposed();
-	tb.scale(_inv_inertia);
-	_inv_inertia_tensor = tb * tbt;
+	Basis diag;
+	diag.scale(_inv_inertia);
+	_inv_inertia_tensor = tb * diag * tbt;
 }
 
 void BodySW::update_inertias() {

servers/physics/joints/generic_6dof_joint_sw.cpp

@@ -219,9 +219,9 @@ Generic6DOFJointSW::Generic6DOFJointSW(BodySW *rbA, BodySW *rbB, const Transform
 }
 
 void Generic6DOFJointSW::calculateAngleInfo() {
-	Basis relative_frame = m_calculatedTransformA.basis.inverse() * m_calculatedTransformB.basis;
+	Basis relative_frame = m_calculatedTransformB.basis.inverse() * m_calculatedTransformA.basis;
 
-	m_calculatedAxisAngleDiff = relative_frame.get_euler();
+	m_calculatedAxisAngleDiff = relative_frame.get_euler_xyz();
 
 	// in euler angle mode we do not actually constrain the angular velocity
 	// along the axes axis[0] and axis[2] (although we do use axis[1]) :