issue #2771: change angular damping to moment. (these two have different meaning, change to the correct one)

cocos2dx/physics/CCPhysicsBody.cpp

@@ -56,8 +56,7 @@ NS_CC_BEGIN
 namespace
 {
     static const float MASS_DEFAULT = 1.0;
-    static const float DENSITY_DEFAULT = 1.0;
+    static const float MOMENT_DEFAULT = 200;
-    static const float ANGULARDAMPING_DEFAULT = 200;
 }
 
 PhysicsBody::PhysicsBody()
@@ -67,11 +66,11 @@ PhysicsBody::PhysicsBody()
 , _dynamic(true)
 , _enable(true)
 , _massDefault(true)
-, _angularDampingDefault(true)
+, _momentDefault(true)
 , _mass(MASS_DEFAULT)
 , _area(0.0)
-, _density(DENSITY_DEFAULT)
+, _density(0)
-, _angularDamping(ANGULARDAMPING_DEFAULT)
+, _moment(MOMENT_DEFAULT)
 , _tag(0)
 {
 }
@@ -217,7 +216,7 @@ bool PhysicsBody::init()
         _info = new PhysicsBodyInfo();
         CC_BREAK_IF(_info == nullptr);
         
-        _info->body = cpBodyNew(PhysicsHelper::float2cpfloat(_mass), PhysicsHelper::float2cpfloat(_angularDamping));
+        _info->body = cpBodyNew(PhysicsHelper::float2cpfloat(_mass), PhysicsHelper::float2cpfloat(_moment));
         CC_BREAK_IF(_info->body == nullptr);
         
         return true;
@@ -233,7 +232,7 @@ void PhysicsBody::setDynamic(bool dynamic)
         if (dynamic)
         {
             cpBodySetMass(_info->body, PhysicsHelper::float2cpfloat(_mass));
-            cpBodySetMoment(_info->body, PhysicsHelper::float2cpfloat(_angularDamping));
+            cpBodySetMoment(_info->body, PhysicsHelper::float2cpfloat(_moment));
         }else
         {
             cpBodySetMass(_info->body, PHYSICS_INFINITY);
@@ -322,21 +321,7 @@ void PhysicsBody::addShape(PhysicsShape* shape)
             }
         }
         
-        if (shape->getAngularDumping() > 0)
+        addMoment(shape->getMoment());
-        {
-            if (shape->getAngularDumping() == INFINITY)
-            {
-                _angularDamping = INFINITY;
-                _angularDampingDefault = false;
-                cpBodySetMoment(_info->body, _angularDamping);
-            }
-            else if (_angularDamping != INFINITY)
-            {
-                _angularDamping = (_angularDampingDefault ? 0 : _angularDamping) + shape->getAngularDumping();
-                _angularDampingDefault = false;
-                cpBodySetMoment(_info->body, _angularDamping);
-            }
-        }
         
         if (_world != nullptr) _world->addShape(shape);
         
@@ -371,12 +356,112 @@ void PhysicsBody::applyTorque(float torque)
 
 void PhysicsBody::setMass(float mass)
 {
+    if (mass <= 0)
+    {
+        return;
+    }
+    
     _mass = mass;
     _massDefault = false;
     
+    // update density
+    if (_mass == PHYSICS_INFINITY)
+    {
+        _density = PHYSICS_INFINITY;
+    }
+    else
+    {
+        if (_area > 0)
+        {
+            _density = _mass / _area;
+        }else
+        {
+            _density = 0;
+        }
+    }
+    
     cpBodySetMass(_info->body, PhysicsHelper::float2cpfloat(_mass));
 }
 
+void PhysicsBody::addMass(float mass)
+{
+    if (mass == PHYSICS_INFINITY)
+    {
+        mass = PHYSICS_INFINITY;
+        _massDefault = false;
+        _density = PHYSICS_INFINITY;
+    }
+    else if (mass == -PHYSICS_INFINITY)
+    {
+        return;
+    }
+    else if (_mass != PHYSICS_INFINITY)
+    {
+        if (_massDefault)
+        {
+            _mass = 0;
+            _massDefault = false;
+        }
+        
+        if (_mass + mass > 0)
+        {
+            _mass +=  mass;
+        }else
+        {
+            _mass = MASS_DEFAULT;
+            _massDefault = true;
+        }
+        
+        if (_area > 0)
+        {
+            _density = _mass / _area;
+        }
+        else
+        {
+            _density = 0;
+        }
+    }
+}
+
+void PhysicsBody::addMoment(float moment)
+{
+    if (moment == PHYSICS_INFINITY)
+    {
+        // if moment is INFINITY, the moment of the body will become INFINITY
+        _moment = PHYSICS_INFINITY;
+        _momentDefault = false;
+    }
+    else if (moment == -PHYSICS_INFINITY)
+    {
+        // if moment is -INFINITY, it won't change
+        return;
+    }
+    else
+    {
+        // if moment of the body is INFINITY is has no effect
+        if (_moment != PHYSICS_INFINITY)
+        {
+            if (_momentDefault)
+            {
+                _moment = 0;
+                _momentDefault = false;
+            }
+            
+            if (_moment + moment > 0)
+            {
+                _moment += moment;
+            }
+            else
+            {
+                _moment = MOMENT_DEFAULT;
+                _momentDefault = true;
+            }
+        }
+    }
+    
+    cpBodySetMoment(_info->body, moment);
+}
+
 void PhysicsBody::setVelocity(Point velocity)
 {
     cpBodySetVel(_info->body, PhysicsHelper::point2cpv(velocity));
@@ -387,12 +472,12 @@ Point PhysicsBody::getVelocity()
     return PhysicsHelper::cpv2point(cpBodyGetVel(_info->body));
 }
 
-void PhysicsBody::setAngularDamping(float angularDamping)
+void PhysicsBody::setMoment(float moment)
 {
-    _angularDamping = angularDamping;
+    _moment = moment;
-    _angularDampingDefault = false;
+    _momentDefault = false;
     
-    cpBodySetMoment(_info->body, _angularDamping);
+    cpBodySetMoment(_info->body, _moment);
 }
 
 PhysicsShape* PhysicsBody::getShapeByTag(int tag)
@@ -434,42 +519,11 @@ void PhysicsBody::removeShape(PhysicsShape* shape)
         _shapes.erase(it);
         
         
-        // deduce the mass, area and angularDamping
+        // deduce the area, mass and moment
-        if (_mass != PHYSICS_INFINITY && shape->getMass() != PHYSICS_INFINITY)
+        // area must update before mass, because the density changes depend on it.
-        {
+        _area -= shape->getArea();
-            if (_mass - shape->getMass() <= 0)
+        addMass(-shape->getMass());
-            {
+        addMoment(-shape->getMoment());
-                _mass = MASS_DEFAULT;
-                _massDefault = true;
-            }else
-            {
-                _mass = _mass = shape->getMass();
-            }
-            
-            _area -= shape->getArea();
-            
-            if (_mass == PHYSICS_INFINITY)
-            {
-                _density = PHYSICS_INFINITY;
-            }
-            else if (_area > 0)
-            {
-                _density = _mass / _area;
-            }
-            else
-            {
-                _density = DENSITY_DEFAULT;
-            }
-            
-            if (_angularDamping - shape->getAngularDumping() > 0)
-            {
-                _angularDamping -= shape->getAngularDumping();
-            }else
-            {
-                _angularDamping = ANGULARDAMPING_DEFAULT;
-                _angularDampingDefault = true;
-            }
-        }
         
         shape->release();
     }

cocos2dx/physics/CCPhysicsBody.h

@@ -172,21 +172,49 @@ public:
     
     /*
      * @brief set the body mass.
+     * @note if you need add/subtract mass to body, don't use setMass(getMass() +/- mass), because the mass of body may be equal to PHYSICS_INFINITY, it will cause some unexpected result, please use addMass() instead.
      */
     void setMass(float mass);
     /*
      * @brief get the body mass.
      */
     inline float getMass() { return _mass; }
+    /*
+     * @brief add mass to body.
+     * if _mass(mass of the body) == PHYSICS_INFINITY, it remains.
+     * if mass == PHYSICS_INFINITY, _mass will be PHYSICS_INFINITY.
+     * if mass == -PHYSICS_INFINITY, _mass will not change.
+     * if mass + _mass <= 0, _mass will equal to MASS_DEFAULT(1.0)
+     * other wise, mass = mass + _mass;
+     */
+    void addMass(float mass);
     
+    /*
+     * @brief set the body moment of inertia.
+     * @note if you need add/subtract moment to body, don't use setMoment(getMoment() +/- moment), because the moment of body may be equal to PHYSICS_INFINITY, it will cause some unexpected result, please use addMoment() instead.
+     */
+    void setMoment(float moment);
+    /*
+     * @brief get the body moment of inertia.
+     */
+    inline float getMoment(float moment) { return _moment; }
+    /*
+     * @brief add moment of inertia to body.
+     * if _moment(moment of the body) == PHYSICS_INFINITY, it remains.
+     * if moment == PHYSICS_INFINITY, _moment will be PHYSICS_INFINITY.
+     * if moment == -PHYSICS_INFINITY, _moment will not change.
+     * if moment + _moment <= 0, _moment will equal to MASS_DEFAULT(1.0)
+     * other wise, moment = moment + _moment;
+     */
+    void addMoment(float moment);
     /*
      * @brief set angular damping.
      */
-    void setAngularDamping(float angularDamping);
+    //void setAngularDamping(float angularDamping);
     /*
      * @brief get angular damping.
      */
-    inline float getAngularDamping() { return _angularDamping; }
+    //inline float getAngularDamping() { return _angularDamping; }
     
     //virtual Clonable* clone() const override;
     
@@ -196,6 +224,7 @@ public:
     inline int getTag() { return _tag; }
     inline void setTag(int tag) { _tag = tag; }
     
+    
 protected:
     
     bool init();
@@ -216,11 +245,12 @@ protected:
     bool                        _dynamic;
     bool                        _enable;
     bool                        _massDefault;
-    bool                        _angularDampingDefault;
+    bool                        _momentDefault;
     float                       _mass;
     float                       _area;
     float                       _density;
-    float                       _angularDamping;
+    float                       _moment;
+    //float                       _angularDamping;
     int                         _tag;
     
     int    _categoryBitmask;

cocos2dx/physics/CCPhysicsShape.cpp

@@ -48,7 +48,7 @@ PhysicsShape::PhysicsShape()
 , _type(Type::UNKNOWN)
 , _area(0)
 , _mass(0)
-, _angularDamping(0)
+, _moment(0)
 , _tag(0)
 , _enable(true)
 {
@@ -234,7 +234,7 @@ bool PhysicsShapeCircle::init(float radius, PhysicsMaterial material/* = Materia
         
         _area = PhysicsHelper::cpfloat2float(cpAreaForCircle(0, radius));
         _mass = _material.density == PHYSICS_INFINITY ? PHYSICS_INFINITY : _material.density * _area;
-        _angularDamping = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForCircle(_mass, 0, radius, PhysicsHelper::point2cpv(offset));
+        _moment = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForCircle(_mass, 0, radius, PhysicsHelper::point2cpv(offset));
         
         _info->add(shape);
         
@@ -273,7 +273,7 @@ bool PhysicsShapeEdgeSegment::init(Point a, Point b, PhysicsMaterial material/*
         CC_BREAK_IF(shape == nullptr);
         
         _mass = PHYSICS_INFINITY;
-        _angularDamping = PHYSICS_INFINITY;
+        _moment = PHYSICS_INFINITY;
         
         _info->add(shape);
         
@@ -311,7 +311,7 @@ bool PhysicsShapeBox::init(Size size, PhysicsMaterial material/* = MaterialDefau
         
         _area = PhysicsHelper::cpfloat2float(cpAreaForPoly(4, ((cpPolyShape*)shape)->verts));
         _mass = _material.density == PHYSICS_INFINITY ? PHYSICS_INFINITY : _material.density * _area;
-        _angularDamping = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForBox(_mass, PhysicsHelper::float2cpfloat(size.width), PhysicsHelper::float2cpfloat(size.height));
+        _moment = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForBox(_mass, PhysicsHelper::float2cpfloat(size.width), PhysicsHelper::float2cpfloat(size.height));
         
         _info->add(shape);
         
@@ -352,7 +352,7 @@ bool PhysicsShapePolygon::init(Point* points, int count, PhysicsMaterial materia
         
         _area = PhysicsHelper::cpfloat2float(cpAreaForPoly(((cpPolyShape*)shape)->numVerts, ((cpPolyShape*)shape)->verts));
         _mass = _material.density == PHYSICS_INFINITY ? PHYSICS_INFINITY : _material.density * _area;
-        _angularDamping = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForPoly(_mass, ((cpPolyShape*)shape)->numVerts, ((cpPolyShape*)shape)->verts, PhysicsHelper::point2cpv(offset));
+        _moment = _mass == PHYSICS_INFINITY ? PHYSICS_INFINITY : cpMomentForPoly(_mass, ((cpPolyShape*)shape)->numVerts, ((cpPolyShape*)shape)->verts, PhysicsHelper::point2cpv(offset));
         
         _info->add(shape);
         
@@ -401,7 +401,7 @@ bool PhysicsShapeEdgeBox::init(Size size, PhysicsMaterial material/* = MaterialD
         CC_BREAK_IF(i < 4);
         
         _mass = PHYSICS_INFINITY;
-        _angularDamping = PHYSICS_INFINITY;
+        _moment = PHYSICS_INFINITY;
         
         initEnd();
         
@@ -450,7 +450,7 @@ bool PhysicsShapeEdgePolygon::init(Point* points, int count, PhysicsMaterial mat
         CC_BREAK_IF(i < count);
         
         _mass = PHYSICS_INFINITY;
-        _angularDamping = PHYSICS_INFINITY;
+        _moment = PHYSICS_INFINITY;
         
         initEnd();
         
@@ -500,7 +500,7 @@ bool PhysicsShapeEdgeChain::init(Point* points, int count, PhysicsMaterial mater
         CC_BREAK_IF(i < count);
         
         _mass = PHYSICS_INFINITY;
-        _angularDamping = PHYSICS_INFINITY;
+        _moment = PHYSICS_INFINITY;
         
         initEnd();
         

cocos2dx/physics/CCPhysicsShape.h

@@ -79,8 +79,8 @@ public:
     inline PhysicsBody* getBody(){ return _body; }
     inline Type getType() { return _type; }
     inline float getArea() { return _area; }
-    inline float getAngularDumping() { return _angularDamping; }
+    inline float getMoment() { return _moment; }
-    void setAngularDumping(float angularDumping);
+    void setMoment(float moment);
     inline void setTag(int tag) { _tag = tag; }
     inline int getTag() { return _tag; }
     void setEnable(bool enable);
@@ -115,7 +115,7 @@ protected:
     Type _type;
     float _area;
     float _mass;
-    float _angularDamping;
+    float _moment;
     PhysicsMaterial _material;
     int _tag;
     bool _enable;

samples/Cpp/TestCpp/Classes/PhysicsTest/PhysicsTest.cpp

@@ -311,9 +311,8 @@ Node* PhysicsDemoLogoSmash::makeBall(float x, float y)
     
     auto body = PhysicsBody::createCircle(0.95, PhysicsMaterial(1, 0, 0));
     body->setMass(1.0);
-    body->setAngularDamping(PHYSICS_INFINITY);
+    body->setMoment(PHYSICS_INFINITY);
     
-    //body->setDynamic(false);
     ball->setPhysicsBody(body);
     
     ball->setPosition(Point(x, y));