closed #5537: add setAutoStep, isAutoStep and step method for PhysicsWorld.

cocos/2d/CCScene.cpp

@@ -113,7 +113,7 @@ void Scene::addChild(Node* child, int zOrder, int tag)
 void Scene::update(float delta)
 {
     Node::update(delta);
-    if (nullptr != _physicsWorld)
+    if (nullptr != _physicsWorld && _physicsWorld->isAutoStep())
     {
         _physicsWorld->update(delta);
     }

cocos/physics/CCPhysicsWorld.cpp

@@ -879,7 +879,19 @@ void PhysicsWorld::setGravity(const Vect& gravity)
     _info->setGravity(gravity);
 }
 
-void PhysicsWorld::update(float delta)
+void PhysicsWorld::step(float delta)
+{
+    if (_autoStep)
+    {
+        CCLOG("Physics Warning: You need to close auto step( setAutoStep(false) ) first");
+    }
+    else
+    {
+        update(delta, true);
+    }
+}
+
+void PhysicsWorld::update(float delta, bool userCall/* = false*/)
 {
     while (_delayDirty)
     {
@@ -889,16 +901,27 @@ void PhysicsWorld::update(float delta)
         _delayDirty = !(_delayAddBodies.size() == 0 && _delayRemoveBodies.size() == 0 && _delayAddJoints.size() == 0 && _delayRemoveJoints.size() == 0);
     }
     
-    _updateTime += delta;
-    if (++_updateRateCount >= _updateRate)
+    if (userCall)
     {
-        _info->step(_updateTime * _speed);
+        _info->step(delta);
         for (auto& body : _bodies)
         {
-            body->update(_updateTime * _speed);
+            body->update(delta);
+        }
+    }
+    else
+    {
+        _updateTime += delta;
+        if (++_updateRateCount >= _updateRate)
+        {
+            _info->step(_updateTime * _speed);
+            for (auto& body : _bodies)
+            {
+                body->update(_updateTime * _speed);
+            }
+            _updateRateCount = 0;
+            _updateTime = 0.0f;
         }
-        _updateRateCount = 0;
-        _updateTime = 0.0f;
     }
     
     if (_debugDrawMask != DEBUGDRAW_NONE)
@@ -916,6 +939,7 @@ PhysicsWorld::PhysicsWorld()
 , _info(nullptr)
 , _scene(nullptr)
 , _delayDirty(false)
+, _autoStep(true)
 , _debugDraw(nullptr)
 , _debugDrawMask(DEBUGDRAW_NONE)
 {

cocos/physics/CCPhysicsWorld.h

@@ -125,14 +125,18 @@ public:
     inline Vect getGravity() const { return _gravity; }
     /** set the gravity value */
     void setGravity(const Vect& gravity);
-    /** Set the speed of physics world, speed is the rate at which the simulation executes. default value is 1.0 */
+    /**
+     * Set the speed of physics world, speed is the rate at which the simulation executes. default value is 1.0
+     * Note: if you setAutoStep(false), this won't work.
+     */
     inline void setSpeed(float speed) { if(speed >= 0.0f) { _speed = speed; } }
     /** get the speed of physics world */
     inline float getSpeed() { return _speed; }
-    /** 
+    /**
      * set the update rate of physics world, update rate is the value of EngineUpdateTimes/PhysicsWorldUpdateTimes.
      * set it higher can improve performance, set it lower can improve accuracy of physics world simulation.
      * default value is 1.0
+     * Note: if you setAutoStep(false), this won't work.
      */
     inline void setUpdateRate(int rate) { if(rate > 0) { _updateRate = rate; } }
     /** get the update rate */
@@ -143,6 +147,20 @@ public:
     /** get the bebug draw mask */
     inline int getDebugDrawMask() { return _debugDrawMask; }
     
+    /**
+     * To control the step of physics, if you want control it by yourself( fixed-timestep for example ), you can set this to false and call step by yourself.
+     * Defaut value is true.
+     * Note: if you set auto step to false, setSpeed and setUpdateRate won't work, you need to control the time step by yourself.
+     */
+    void setAutoStep(bool autoStep){ _autoStep = autoStep; }
+    /** Get the auto step */
+    bool isAutoStep() { return _autoStep; }
+    /**
+     * The step for physics world, The times passing for simulate the physics.
+     * Note: you need to setAutoStep(false) first before it can work.
+     */
+    void step(float delta);
+    
 protected:
     static PhysicsWorld* construct(Scene& scene);
     bool init(Scene& scene);
@@ -150,7 +168,7 @@ protected:
     virtual void addBody(PhysicsBody* body);
     virtual void addShape(PhysicsShape* shape);
     virtual void removeShape(PhysicsShape* shape);
-    virtual void update(float delta);
+    virtual void update(float delta, bool userCall = false);
     
     virtual void debugDraw();
     
@@ -183,6 +201,7 @@ protected:
     Scene* _scene;
     
     bool _delayDirty;
+    bool _autoStep;
     PhysicsDebugDraw* _debugDraw;
     int _debugDrawMask;