Fix for issue 407. Reverted a previous bad fix. Also ran Visual Studi…

…o static analysis and fixed a couple things.

.gitignore

@@ -17,3 +17,4 @@
 imgui.ini
 **/xcshareddata
 *.ini
+*.lastcodeanalysissucceeded

Box2D/Box2D/Collision/Shapes/b2ChainShape.cpp

@@ -37,6 +37,11 @@ void b2ChainShape::CreateLoop(const b2Vec2* vertices, int32 count)
 {
 	b2Assert(m_vertices == NULL && m_count == 0);
 	b2Assert(count >= 3);
+	if (count < 3)
+	{
+		return;
+	}
+
 	for (int32 i = 1; i < count; ++i)
 	{
 		b2Vec2 v1 = vertices[i-1];

Box2D/Box2D/Dynamics/Contacts/b2ContactSolver.cpp

@@ -24,6 +24,7 @@
 #include <Box2D/Dynamics/b2World.h>
 #include <Box2D/Common/b2StackAllocator.h>
 
+// Solver debugging is normally disabled because the block solver sometimes has to deal with a poorly conditioned effective mass matrix.
 #define B2_DEBUG_SOLVER 0
 
 bool g_blockSolve = true;
@@ -375,7 +376,7 @@ void b2ContactSolver::SolveVelocityConstraints()
 			// Block solver developed in collaboration with Dirk Gregorius (back in 01/07 on Box2D_Lite).
 			// Build the mini LCP for this contact patch
 			//
-			// vn = A * x + b, vn >= 0, , vn >= 0, x >= 0 and vn_i * x_i = 0 with i = 1..2
+			// vn = A * x + b, vn >= 0, x >= 0 and vn_i * x_i = 0 with i = 1..2
 			//
 			// A = J * W * JT and J = ( -n, -r1 x n, n, r2 x n )
 			// b = vn0 - velocityBias
@@ -483,10 +484,8 @@ void b2ContactSolver::SolveVelocityConstraints()
 				//
 				x.x = - cp1->normalMass * b.x;
 				x.y = 0.0f;
-#if B2_DEBUG_SOLVER == 1
 				vn1 = 0.0f;
 				vn2 = vc->K.ex.y * x.x + b.y;
-#endif
 				if (x.x >= 0.0f && vn2 >= 0.0f)
 				{
 					// Get the incremental impulse
@@ -526,10 +525,8 @@ void b2ContactSolver::SolveVelocityConstraints()
 				//
 				x.x = 0.0f;
 				x.y = - cp2->normalMass * b.y;
-#if B2_DEBUG_SOLVER == 1
 				vn1 = vc->K.ey.x * x.y + b.x;
 				vn2 = 0.0f;
-#endif
 
 				if (x.y >= 0.0f && vn1 >= 0.0f)
 				{

Box2D/Box2D/Dynamics/b2Body.cpp

@@ -213,6 +213,11 @@ b2Fixture* b2Body::CreateFixture(const b2Shape* shape, float32 density)
 
 void b2Body::DestroyFixture(b2Fixture* fixture)
 {
+	if (fixture == nullptr)
+	{
+		return;
+	}
+
 	b2Assert(m_world->IsLocked() == false);
 	if (m_world->IsLocked() == true)
 	{
@@ -266,9 +271,9 @@ void b2Body::DestroyFixture(b2Fixture* fixture)
 		fixture->DestroyProxies(broadPhase);
 	}
 
-	fixture->Destroy(allocator);
 	fixture->m_body = NULL;
 	fixture->m_next = NULL;
+	fixture->Destroy(allocator);
 	fixture->~b2Fixture();
 	allocator->Free(fixture, sizeof(b2Fixture));