【COCOS2DX-BOX2D遊戲開發之三】讀取tiledmap的tmx阻擋(轉）

http://blog.csdn.net/teng_ontheway/article/details/21704279
做一款像素遊戲項目，需要讀取TMX文件中的阻擋區域，生成box2d的fixture，來做阻擋使用cocos2dx版本: 2.2.2

1.在tmx文件中創建一個”Physics”的層，用來存放編輯器中生成的各種阻擋塊
編輯器中主要有polygone, polyline，box和circle4種，其實box也屬於polygone

2.我的tiled map 版本Version 0.9.1
查看tmx文件,增加的層屬於是不會被渲染的，所以添加多個層對效率也沒有什麼影響, 我們此處叫”Physics”
上圖的4個圖形，分別對應下圖XML的4個

polyline讀取一個初始點x,y,然後讀取一些列相對於初始點的偏移值
box讀取x,y,width,height
circle讀取起始點x,y，外加直徑width(height)足以，因爲無法構造橢圓的b2Shape，所以我們構造圓
polygon讀取起始點x,y，然後讀取一些列相對於初始點的偏移值，類似於polyline

3.cocos2dx中解析此文件的時CCTMXXMLParser.cpp 大概在623行，但是代碼中只解析了polygon,polyline和circle處解析代碼爲空,我們在此處添加完全

[cpp] view plain copy 在CODE上查看代碼片派生到我的代碼片

else if (elementName == "polygon")   
    {  
        // find parent object's dict and add polygon-points to it  
        ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();  
        CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();  

        // get points value string  
        const char* value = valueForKey("points", attributeDict);  
        if(value)  
        {  
            CCArray* pPointsArray = new CCArray;  

            // parse points string into a space-separated set of points  
            stringstream pointsStream(value);  
            string pointPair;  
            while(std::getline(pointsStream, pointPair, ' '))  
            {  
                // parse each point combo into a comma-separated x,y point  
                stringstream pointStream(pointPair);  
                string xStr,yStr;  
                char buffer[32] = {0};  

                CCDictionary* pPointDict = new CCDictionary;  

                // set x  
                if(std::getline(pointStream, xStr, ','))  
                {  
                    int x = atoi(xStr.c_str()) + (int)objectGroup->getPositionOffset().x;  
                    sprintf(buffer, "%d", x);  
                    CCString* pStr = new CCString(buffer);  
                    pStr->autorelease();  
                    pPointDict->setObject(pStr, "x");  
                }  

                // set y  
                if(std::getline(pointStream, yStr, ','))  
                {  
                    int y = atoi(yStr.c_str()) + (int)objectGroup->getPositionOffset().y;  
                    sprintf(buffer, "%d", y);  
                    CCString* pStr = new CCString(buffer);  
                    pStr->autorelease();  
                    pPointDict->setObject(pStr, "y");  
                }  

                // add to points array  
                pPointsArray->addObject(pPointDict);  
                pPointDict->release();  
            }  

            dict->setObject(pPointsArray, "points");  
            pPointsArray->release();  

            dict->setObject(dict->objectForKey("points"), "polygonPoints");  
        }  
    }   
    else if (elementName == "polyline")  
    {  
        // find parent object's dict and add polyline-points to it  
        // ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();  
        // CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();  
        // TODO: dict->setObject:[attributeDict objectForKey:@"points"] forKey:@"polylinePoints"];  

        // ------Added by Teng.start  
        // find parent object's dict and add polygon-points to it  
        ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();  
        CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();  

        // get points value string  
        const char* value = valueForKey("points", attributeDict);  
        if(value)  
        {  
            CCArray* pPointsArray = new CCArray;  

            // parse points string into a space-separated set of points  
            stringstream pointsStream(value);  
            string pointPair;  
            while(std::getline(pointsStream, pointPair, ' '))  
            {  
                // parse each point combo into a comma-separated x,y point  
                stringstream pointStream(pointPair);  
                string xStr,yStr;  
                char buffer[32] = {0};  

                CCDictionary* pPointDict = new CCDictionary;  

                // set x  
                if(std::getline(pointStream, xStr, ','))  
                {  
                    int x = atoi(xStr.c_str()) + (int)objectGroup->getPositionOffset().x;  
                    sprintf(buffer, "%d", x);  
                    CCString* pStr = new CCString(buffer);  
                    pStr->autorelease();  
                    pPointDict->setObject(pStr, "x");  
                }  

                // set y  
                if(std::getline(pointStream, yStr, ','))  
                {  
                    int y = atoi(yStr.c_str()) + (int)objectGroup->getPositionOffset().y;  
                    sprintf(buffer, "%d", y);  
                    CCString* pStr = new CCString(buffer);  
                    pStr->autorelease();  
                    pPointDict->setObject(pStr, "y");  
                }  

                // add to points array  
                pPointsArray->addObject(pPointDict);  
                pPointDict->release();  
            }  

            dict->setObject(pPointsArray, "points");  
            pPointsArray->release();  

            dict->setObject(dict->objectForKey("points"), "polylinePoints");  
        }  

        // ------Added by Teng.end  
    }  
    else if (elementName == "ellipse")  
    {  
        // ------Added by Teng.start  
        // Do nothing...  
        ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();  
        CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();  

        CCObject *obj = new CCObject;  
        dict->setObject(obj, "ellipse");  
        obj->release();  
        // ------Added by Teng.end  
    }

4.剩下的就是我們在程序中獲取出這些阻擋區域了
[cpp] view plain copy 在CODE上查看代碼片派生到我的代碼片

bool Map::createPhysical(b2World *world)  
{  
    b2BodyDef body_def;  
    body_def.type = b2_staticBody;  
    body_def.position.SetZero();  
    mBody = world->CreateBody(&body_def);  

    // 找出阻擋區域所在的層  
    ObjectGroup* group = mTiledMap->objectGroupNamed("Physics");  

    CCArray* array = group->getObjects();  
    CCDictionary* dict;  
    CCObject* pObj = NULL;  
    CCARRAY_FOREACH(array, pObj)  
    {  
        dict = (CCDictionary*)pObj;  
        if (!dict)  
            continue;  

        b2FixtureDef fixture_def;  

        StaticBlockObject *sb_obj = new StaticBlockObject();  

        sb_obj->density = 1.0f;  
        sb_obj->friction = 0.2f;  
        sb_obj->restitution = 0.f;  

        // 讀取所有形狀的起始點  
        float x = ((CCString*)dict->objectForKey("x"))->floatValue();  
        float y = ((CCString*)dict->objectForKey("y"))->floatValue();  

        b2Shape* shape = NULL;  

        //多邊形  
        CCObject *polygon = dict->objectForKey("polygonPoints");  
        if (polygon) {  
            CCArray *polygon_points = (CCArray*)polygon;  

            std::vector<b2Vec2> points;  

            // 必須將所有讀取的定點逆向，因爲翻轉y之後，三角形定點的順序已經逆序了，構造b2PolygonShape會crash  
            int c =polygon_points->count();  
            points.resize(c);  
            c--;  

            CCDictionary* pt_dict;  
            CCObject* obj = NULL;  
            CCARRAY_FOREACH(polygon_points, obj)  
            {  
                pt_dict = (CCDictionary*)obj;  

                if (!pt_dict) {  
                    continue;  
                }  

                // 相對於起始點的偏移  
                float offx = ((CCString*)pt_dict->objectForKey("x"))->floatValue();  
                float offy = ((CCString*)pt_dict->objectForKey("y"))->floatValue();  

                points[c--] = (b2Vec2((x + offx) / PTM_RATIO, (y-offy) / PTM_RATIO));  
            }  

            b2PolygonShape *ps = new b2PolygonShape();  
            ps->Set(&points[0], points.size());  
            fixture_def.shape = ps;  

            shape = ps;  

            sb_obj->shape = StaticBlockObject::ST_POLYGON;  
        } else if (polygon = dict->objectForKey("polylinePoints")){  
            CCArray *polyline_points = (CCArray*)polygon;  

            std::vector<b2Vec2> points;  

            CCDictionary* pt_dict;  
            CCObject* obj = NULL;  
            CCARRAY_FOREACH(polyline_points, obj)  
            {  
                pt_dict = (CCDictionary*)obj;  

                if (!pt_dict) {  
                    continue;  
                }  

                float offx = ((CCString*)pt_dict->objectForKey("x"))->floatValue();  
                float offy = ((CCString*)pt_dict->objectForKey("y"))->floatValue();  
                points.push_back(b2Vec2((x + offx) / PTM_RATIO, (y-offy) / PTM_RATIO));  
            }  

            b2ChainShape *ps = new b2ChainShape();  
            ps->CreateChain(&points[0], points.size());  
            fixture_def.shape = ps;  

            shape = ps;  

            sb_obj->shape = StaticBlockObject::ST_POLYGON;  
        } else if (dict->objectForKey("ellipse")) {  
            float width = ((CCString*)dict->objectForKey("width"))->floatValue();  
            float height = ((CCString*)dict->objectForKey("height"))->floatValue();  

            b2CircleShape *ps = new b2CircleShape;  
            ps->m_p.Set((x+width/2) / PTM_RATIO, ((y+height/2)) / PTM_RATIO);  
            ps->m_radius = width/2/PTM_RATIO;  
            fixture_def.shape = ps;  

            shape = ps;  

            sb_obj->shape = StaticBlockObject::ST_CIRCLE;  
        } else {  
            float width = ((CCString*)dict->objectForKey("width"))->floatValue();  
            float height = ((CCString*)dict->objectForKey("height"))->floatValue();  

            b2PolygonShape *ps = new b2PolygonShape;  
            ps->SetAsBox(width/2/PTM_RATIO, height/2/PTM_RATIO, b2Vec2((x+width/2)/PTM_RATIO, (y+height/2)/PTM_RATIO), 0);  
            fixture_def.shape = ps;  

            shape = ps;  

            sb_obj->shape = StaticBlockObject::ST_POLYGON;  

        }  

        fixture_def.density = sb_obj->density;  
        fixture_def.friction = sb_obj->friction;  
        fixture_def.restitution = sb_obj->restitution;  

        b2Fixture *fixture = mBody->CreateFixture(&fixture_def);  
        sb_obj->fixture = fixture;  

        if (shape) {  
            delete shape;  
            shape = NULL;  
        }  

        // Storage the Static block object.  
        mStaticBlockList.push_back(sb_obj);  
    }  

    return true;  
}  

附帶上StaticBlockObject代碼，這個主要用來記錄阻擋的類型、屬性，以後用來做阻擋判斷
[cpp] view plain copy 在CODE上查看代碼片派生到我的代碼片
/** 
    Storage fixture user data. 
    use for b2Fixture user data. 
 */  
class iFixtureUserData  
{  
public:  
    typedef uint BodyType;  
    typedef uint FixtureType;  

    static const BodyType   BT_Avata = 0x000;  // no any use...  
    static const FixtureType FT_None = 0x000;  

    static const BodyType BT_Map  = 0x1000;  
    static const FixtureType FT_STATIC_OBJ = 0x1F01;  
    static const FixtureType FT_DYNAMIC_OBJ = 0x1F02;  

    //  
    static const BodyType BT_Role = 0x2000;  
    static const BodyType BT_Bullet = 0x2100;  

    static const FixtureType FT_BODY = 0x2F01;  
    static const FixtureType FT_FOOT = 0x2F02;  


public:  
    iFixtureUserData(BodyType body_type, FixtureType fixture_type):  
        mBodyType(body_type), mFixtureType(fixture_type){  
    }  

    virtual ~iFixtureUserData() {  

    }  

    inline BodyType getBodyType() { return mBodyType; }  
    inline FixtureType getFixtureType() { return mFixtureType; }  

protected:  
    BodyType mBodyType;  
    FixtureType mFixtureType;  
};  

/** 
 Block object. 
 specify a block area in physics engine. */  
class StaticBlockObject : public iFixtureUserData {  
public:  
    StaticBlockObject():  
    iFixtureUserData(BT_Map, FT_STATIC_OBJ),  
    fixture(NULL),  
    half_block(false)  
    {  

    }  
    enum ShapeType {  
        ST_POLYGON = 0,  
        ST_CIRCLE = 1,  
        ST_EDGE = 2  
    };  

    ShapeType shape;        // The shape type.  

    float density;  
    float friction;  
    float restitution;  

    b2Fixture *fixture;  

    bool half_block;  
};  

typedef std::vector<StaticBlockObject *> StaticBlockList;

因爲是從代碼中直接複製的，但無非實現了下面幾個功能：
1.在map中找到”Physics”層
2.遍歷讀取所有圖形的起始點，並分析是何種圖形，並讀取相應的屬性
3.用讀取的每個圖形來構造b2Shape，用地圖的body來構造b2Fixture
其中有幾個地方需要注意：
1.因爲Box2d和遊戲中使用的單位不同,分別是米和像素，所以要用PTM_RATIO宏來轉換
2.polygon讀取的所有點來構造b2PolygonShape,這個序列必須是讀取的所有點的反向列表，否則會報一個計算center斷言錯誤
產生這個的原因是因爲：tmx中的頂點座標系是地圖左上角，遊戲中是左下角，CCTMXXMLParser.cpp中解析起始點的時候，自動幫我們轉爲遊戲中的座標
於是tmx中的1，2，3，4的頂點序列，構成的區域是凸多邊形的內部，轉換後就成爲了4，3，2，1，構成的是凸多邊形的外部
polyline因爲不是閉合的，無所謂逆向一說
[cpp] view plain copy 在CODE上查看代碼片派生到我的代碼片

std::vector<b2Vec2> points;  

          // 必須將所有讀取的定點逆向，因爲翻轉y之後，三角形定點的順序已經逆序了，構造b2PolygonShape會crash  
          int c =polygon_points->count();  
          points.resize(c);  
          c--;  

          CCDictionary* pt_dict;  
          CCObject* obj = NULL;  
          CCARRAY_FOREACH(polygon_points, obj)  
          {  
              pt_dict = (CCDictionary*)obj;  

              if (!pt_dict) {  
                  continue;  
              }  

              // 相對於起始點的偏移  
              float offx = ((CCString*)pt_dict->objectForKey("x"))->floatValue();  
              float offy = ((CCString*)pt_dict->objectForKey("y"))->floatValue();  

              points[c--] = (b2Vec2((x + offx) / PTM_RATIO, (y-offy) / PTM_RATIO));  
          }  

          b2PolygonShape *ps = new b2PolygonShape();  
          ps->Set(&points[0], points.size());  
          fixture_def.shape = ps;

5.傳個效果圖：

【COCOS2DX-BOX2D遊戲開發之三】讀取tiledmap的tmx阻擋(轉）

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【COCOS2DX-BOX2D遊戲開發之三】讀取tiledmap的tmx阻擋(轉）

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【COCOS2DX-BOX2D遊戲開發之三】 讀取tiledmap的tmx阻擋(轉）

【COCOS2DX-BOX2D遊戲開發之三】讀取tiledmap的tmx阻擋(轉）