bugfix: crash in btSoftBody::setPose() due to singular matrix

stephengold · stephengold · commit 78d02c781f8e · 2026-03-22T14:28:22.000-07:00
diff --git a/src/main/native/bullet3/BulletSoftBody/btSoftBody.cpp b/src/main/native/bullet3/BulletSoftBody/btSoftBody.cpp
@@ -1225,7 +1225,12 @@ void btSoftBody::setPose(bool bvolume, bool bframe)
 		m_pose.m_aqq[1] += mq.y() * q;
 		m_pose.m_aqq[2] += mq.z() * q;
 	}
+      btScalar det = m_pose.m_aqq.determinant();// stephengold added 2026-03-22
+      if (btFabs(det) > SIMD_EPSILON) {// stephengold added 2026-03-22
 	m_pose.m_aqq = m_pose.m_aqq.inverse();
+      } else {// stephengold added 2026-03-22
+        m_pose.m_aqq.setIdentity();// stephengold added 2026-03-22
+      }// stephengold added 2026-03-22
 
 	updateConstants();
 }

Original file line number	Diff line number	Diff line change
`@@ -1225,7 +1225,12 @@ void btSoftBody::setPose(bool bvolume, bool bframe)`
`1225`	`1225`	`m_pose.m_aqq[1] += mq.y() * q;`
`1226`	`1226`	`m_pose.m_aqq[2] += mq.z() * q;`
`1227`	`1227`	`}`
	`1228`	`+ btScalar det = m_pose.m_aqq.determinant();// stephengold added 2026-03-22`
	`1229`	`+ if (btFabs(det) > SIMD_EPSILON) {// stephengold added 2026-03-22`
`1228`	`1230`	`m_pose.m_aqq = m_pose.m_aqq.inverse();`
	`1231`	`+ } else {// stephengold added 2026-03-22`
	`1232`	`+ m_pose.m_aqq.setIdentity();// stephengold added 2026-03-22`
	`1233`	`+ }// stephengold added 2026-03-22`
`1229`	`1234`
`1230`	`1235`	`updateConstants();`
`1231`	`1236`	`}`