做一款像素游戏项目,需要读取TMX文件中的阻挡区域,生成box2d的fixture,来做阻挡 使用cocos2dx版本: 2.2.2
1.在tmx文件中创建一个"Physics"的层,用来存放编辑器中生成的各种阻挡块
编辑器中主要有polygone, polyline,box和circle4种,其实box也属于polygone
![【COCOS2DX-BOX2D游戏开发之三】 读取tiledmap的tmx阻挡_第1张图片](http://img.e-com-net.com/image/info5/f1437703fa454668a406423cc5e62235.jpg)
2.我的tiled map 版本Version 0.9.1
查看tmx文件,增加的层属于<Objectgroup>是不会被渲染的,所以添加多个层对效率也没有什么影响, 我们此处叫"Physics"
上图的4个图形,分别对应下图XML的4个<object></object>
![【COCOS2DX-BOX2D游戏开发之三】 读取tiledmap的tmx阻挡_第2张图片](http://img.e-com-net.com/image/info5/b74c2ccc12db4f5193bed500b26af7b6.jpg)
polyline读取一个初始点x,y,然后读取一些列相对于初始点的偏移值
box读取x,y,width,height
circle读取起始点x,y,外加直径width(height)足以,因为无法构造椭圆的b2Shape,所以我们构造圆
polygon读取起始点x,y,然后读取一些列相对于初始点的偏移值,类似于polyline
3.cocos2dx中解析此文件的时CCTMXXMLParser.cpp 大概在623行,但是代码中只解析了polygon,polyline和circle处解析代码为空,我们在此处添加完全
- else if (elementName == "polygon")
- {
-
- ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();
- CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();
-
-
- const char* value = valueForKey("points", attributeDict);
- if(value)
- {
- CCArray* pPointsArray = new CCArray;
-
-
- stringstream pointsStream(value);
- string pointPair;
- while(std::getline(pointsStream, pointPair, ' '))
- {
-
- stringstream pointStream(pointPair);
- string xStr,yStr;
- char buffer[32] = {0};
-
- CCDictionary* pPointDict = new CCDictionary;
-
-
- 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");
- }
-
-
- 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");
- }
-
-
- pPointsArray->addObject(pPointDict);
- pPointDict->release();
- }
-
- dict->setObject(pPointsArray, "points");
- pPointsArray->release();
-
- dict->setObject(dict->objectForKey("points"), "polygonPoints");
- }
- }
- else if (elementName == "polyline")
- {
-
-
-
-
-
-
-
- ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();
- CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();
-
-
- const char* value = valueForKey("points", attributeDict);
- if(value)
- {
- CCArray* pPointsArray = new CCArray;
-
-
- stringstream pointsStream(value);
- string pointPair;
- while(std::getline(pointsStream, pointPair, ' '))
- {
-
- stringstream pointStream(pointPair);
- string xStr,yStr;
- char buffer[32] = {0};
-
- CCDictionary* pPointDict = new CCDictionary;
-
-
- 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");
- }
-
-
- 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");
- }
-
-
- pPointsArray->addObject(pPointDict);
- pPointDict->release();
- }
-
- dict->setObject(pPointsArray, "points");
- pPointsArray->release();
-
- dict->setObject(dict->objectForKey("points"), "polylinePoints");
- }
-
-
- }
- else if (elementName == "ellipse")
- {
-
-
- ObjectGroup* objectGroup = (ObjectGroup*)m_pObjectGroups->lastObject();
- CCDictionary* dict = (CCDictionary*)objectGroup->getObjects()->lastObject();
-
- CCObject *obj = new CCObject;
- dict->setObject(obj, "ellipse");
- obj->release();
-
- }
4.剩下的就是我们在程序中获取出这些阻挡区域了
- bool Map::createPhysical(b2World *world)
- {
- b2BodyDef body_def;
- body_def.type = b2_staticBody;
- body_def.position.SetZero();
- mBody = world->CreateBody(&body_def);
-
-
- 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;
-
-
- float x = ((CCString*)dict->objectForKey("x"))->floatValue();
- float y = ((CCString*)dict->objectForKey("y"))->floatValue();
-
- b2Shape* shape = NULL;
-
-
- CCObject *polygon = dict->objectForKey("polygonPoints");
- if (polygon) {
- CCArray *polygon_points = (CCArray*)polygon;
-
- std::vector<b2Vec2> points;
-
-
- 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;
- }
-
-
- 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;
- }
-
-
- mStaticBlockList.push_back(sb_obj);
- }
-
- return true;
- }
附带上StaticBlockObject代码,这个主要用来记录阻挡的类型、属性,以后用来做阻挡判断
-
-
-
-
- class iFixtureUserData
- {
- public:
- typedef uint BodyType;
- typedef uint FixtureType;
-
- static const BodyType BT_Avata = 0x000;
- 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;
- };
-
-
-
-
- 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;
-
- float density;
- float friction;
- float restitution;
-
- b2Fixture *fixture;
-
- bool half_block;
- };
-
- typedef std::vector<StaticBlockObject *> StaticBlockList;
因为是从代码中直接复制的,但无非实现了下面几个功能:
1.在map中找到"Physics"层
2.遍历读取所有图形的起始点,并分析是何种图形,并读取相应的属性
3.用读取的每个图形来构造b2Shape,用地图的body来构造b2Fixture
其中有几个地方需要注意:
1.因为Box2d和游戏中使用的单位不同,分别是米和像素,所以要用PTM_RATIO宏来转换
2.polygon读取的所有点来构造b2PolygonShape,这个序列必须是读取的所有点的反向列表,否则会报一个计算center断言错误
产生这个的原因是因为:tmx中的顶点坐标系是地图左上角,游戏中是左下角,CCTMXXMLParser.cpp中解析起始点的时候,自动帮我们转为游戏中的坐标
于是tmx中的1,2,3,4的顶点序列,构成的区域是凸多边形的内部,转换后就成为了4,3,2,1,构成的是凸多边形的外部
polyline因为不是闭合的,无所谓逆向一说
- std::vector<b2Vec2> points;
-
-
- 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;
- }
-
-
- 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.传个效果图:
![【COCOS2DX-BOX2D游戏开发之三】 读取tiledmap的tmx阻挡_第3张图片](http://img.e-com-net.com/image/info5/367534a1a0944e888dd3a04dcd4ca730.jpg)