动画的碰撞检测

碧潭

实现这样一个功能：飞机在盘旋，按下键盘左键，飞机释放小飞机，给小飞机一个路径，垂直向下，当小飞机碰到地面后，消失。
问题是：1。碰撞检测从开始释放小飞机，iv.hits()的返回值就为true，就是一直都是碰撞状态，明明离地面200多，不知道什么原因。
           2. 如何得到碰撞到地面的位置？
代码如下：

1. osg::ref_ptr<osg::AnimationPath> createAnimationPath(osg::Vec3& center,float radius,float looptime)
   
2. {
   
3. //创建一个path对象
   
4. osg::ref_ptr<osg::AnimationPath> animationPath = new osg::AnimationPath();
   
5. //设置动画模式为循环（LOOP）。LOOP：循环，SWING：单摆，NO_LOOPING：不循环
   
6. animationPath->setLoopMode(osg::AnimationPath::LOOP);
   
7. //关键点数
   
8. int numPoint = 60;
   
9. //每次偏移角度
   
10. float yaw = 0.0f;
    
11. float yaw_delta = 2.0f*osg::PI/((float)(numPoint-1.0f));
    
12. //倾斜角度
    
13. float roll = osg::inDegrees(45.0f);
    
14. //时间偏移
    
15. float time = 0.0f;
    
16. float time_delta = looptime/((float)numPoint);
    
17. for(int i = 0;i<numPoint;i++)
    
18. {
    
19.   //关键点位置
    
20.   osg::Vec3 position(center+osg::Vec3(sinf(yaw)*radius,cosf(yaw)*radius,0.0f));
    
21.   //关键点角度
    
22.   osg::Quat rotation(osg::Quat(roll,osg::Vec3(0.0,1.0,0.0))*osg::Quat(-(yaw+osg::inDegrees(90.0f)),osg::Vec3(0.0,0.0,1.0)));
    
23.   //插入path，把关键点与时间压入形成path
    
24.   animationPath->insert(time,osg::AnimationPath::ControlPoint(position,rotation));
    
25.   yaw += yaw_delta;
    
26.   time += time_delta;
    
27. }
    
28. return animationPath.get();
    
29. }
    
30. osg::ref_ptr<osg::AnimationPath> createAnimationPath1(osg::Vec3& pos)
    
31. {
    
32. osg::ref_ptr<osg::AnimationPath> animationPath = new osg::AnimationPath();
    
33. animationPath->setLoopMode(osg::AnimationPath::LOOP);
    
34. int numPoint = 60;
    
35. float yaw = 0.0f;
    
36. float yaw_delta = 2.0f;
    
37. float roll = osg::inDegrees(45.0f);
    
38. float time = 0.0f;
    
39. float time_delta = 0.5f;
    
40. for(int i=0;i<numPoint;i++)
    
41. {
    
42.   osg::Vec3 position(pos+osg::Vec3(0.0f,0.0f,-yaw));
    
43.   osg::Quat rotation(osg::Quat(roll,osg::Vec3(0.0,1.0,0.0)));
    
44.   animationPath->insert(time,osg::AnimationPath::ControlPoint(position,rotation));
    
45.   yaw += yaw_delta;
    
46.   time += time_delta;
    
47. }
    
48. return animationPath.get();
    
49. }
    
50. class CheckPengEventHandler : public osg::NodeCallback
    
51. {
    
52. public:
    
53. CheckPengEventHandler()  
    
54. {
    
55.   
    
56. }
    
57. virtual void operator()(osg::Node* node,osg::NodeVisitor* nv)
    
58. {  
    
59.   osg::PositionAttitudeTransform* pat = dynamic_cast<osg::PositionAttitudeTransform*>(node);  
    
60.   osgUtil::IntersectVisitor iv;   
    
61.   osg::ref_ptr<osg::LineSegment> lineZ = new osg::LineSegment(pat->getPosition()+osg::Vec3(0.0f,0.0f,2.0f),pat->getPosition()+osg::Vec3(0.0f,0.0f,-2.0f));
    
62.   iv.addLineSegment(lineZ.get());  
    
63.   if(iv.hits())
    
64.   {
    
65.    node->setNodeMask(0);
    
66.   }   
    
67. }
    
68. };
    
69. 
    
70. class UseEventHandler:public osgGA::GUIEventHandler
    
71. {
    
72. public:
    
73. UseEventHandler(osg::ref_ptr<osg::PositionAttitudeTransform> pat,osg::ref_ptr<osg::AnimationPath> animationPath
    
74.   ,osg::ref_ptr<osg::PositionAttitudeTransform> pat1)  
    
75.   :pat(pat),animationPath(animationPath),pat1(pat1)
    
76. {
    
77.   
    
78. }
    
79. virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa)
    
80. {
    
81.   osgViewer::Viewer* viewer = dynamic_cast<osgViewer::Viewer*>(&aa);
    
82.   if(!viewer) return false;
    
83.   osg::ref_ptr<osg::Group> group = dynamic_cast<osg::Group*>(viewer->getSceneData());  
    
84.   switch(ea.getEventType())
    
85.   {
    
86.   case osgGA::GUIEventAdapter::KEYDOWN:
    
87.    {
    
88.     if(ea.getKey()==0xFF51)
    
89.     {
    
90.      pat->setUpdateCallback(new osg::AnimationPathCallback(animationPath.get(),0.0f,1.0f));
    
91.     }
    
92.     if(ea.getKey() == 0xFF53)
    
93.     {   
    
94.      osg::Vec3 position = pat->getPosition();
    
95.      group->addChild(pat1.get());
    
96.      group->getChild(0)->asGroup()->removeChild(pat1);
    
97.      pat1->setNodeMask(1);
    
98.      osg::ref_ptr<osg::AnimationPath> animationPath1 = new osg::AnimationPath();
    
99.                  animationPath1 = createAnimationPath1(position);
    
100.      pat1->addUpdateCallback(new osg::AnimationPathCallback(animationPath1.get(),0.0f,1.0f));
     
101.      pat1->addUpdateCallback(new CheckPengEventHandler());
     
102.     }
     
103.    }
     
104.    break;  
     
105.   default:
     
106.    break;
     
107.   }
     
108.   return false;
     
109. }
     
110. private:
     
111. osg::ref_ptr<osg::PositionAttitudeTransform> pat,pat1;
     
112. osg::ref_ptr<osg::AnimationPath> animationPath;
     
113. };
     
114. 
     
115. int _tmain(int argc, _TCHAR* argv[])
     
116. {
     
117. osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();
     
118. osg::ref_ptr<osg::Group> root = new osg::Group();
     
119. osg::ref_ptr<osg::Node> cessna = osgDB::readNodeFile("cessna.osg");  
     
120. osg::ref_ptr<osg::Node> node = osgDB::readNodeFile("lz.osg");
     
121. osg::ref_ptr<osg::Node> glider = osgDB::readNodeFile("glider.osg");
     
122. //得到包围盒，来确定动画旋转中心
     
123. const osg::BoundingSphere& bs = cessna->getBound();
     
124. osg::Vec3 position = bs.center() + osg::Vec3(0.0f,0.0f,200.0f);
     
125. //缩放
     
126. float size = 100.0f/bs.radius()*0.3f;
     
127. //创建路径
     
128. osg::ref_ptr<osg::AnimationPath> animationPath = new osg::AnimationPath();
     
129. animationPath = createAnimationPath(position,200.0f,30.0f);
     
130. osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform();
     
131. osg::ref_ptr<osg::MatrixTransform> mt1 = new osg::MatrixTransform();
     
132. osg::ref_ptr<osg::MatrixTransform> mtTerr = new osg::MatrixTransform();
     
133. //OSG确保只有STATIC数据可以进行图形渲染
     
134. mt->setDataVariance(osg::Object::STATIC);
     
135. mt1->setDataVariance(osg::Object::STATIC);
     
136. //进行适当的变换
     
137. mtTerr->setMatrix(osg::Matrix::translate(0.0f,0.0f,0.0f));
     
138. mtTerr->addChild(node.get());
     
139. mt->setMatrix(osg::Matrix::translate(bs.center())*
     
140.   osg::Matrix::scale(size,size,size));
     
141. mt->addChild(cessna.get());
     
142. mt1->setMatrix(osg::Matrix::scale(0.2,0.2,0.2)*osg::Matrix::rotate(osg::inDegrees(90.0f),1.0f,0.0f,0.0f));
     
143. mt1->addChild(glider.get());
     
144. osg::ref_ptr<osg::PositionAttitudeTransform> pat = new osg::PositionAttitudeTransform();
     
145. osg::ref_ptr<osg::PositionAttitudeTransform> pat1 = new osg::PositionAttitudeTransform();
     
146. pat->addChild(mt.get());
     
147. pat1->addChild(mt1.get());
     
148. pat1->setNodeMask(0);
     
149. pat->addChild(pat1.get());
     
150. root->addChild(pat.get());
     
151. root->addChild(mtTerr.get());
     
152. osgUtil::Optimizer optimizer;
     
153. optimizer.optimize(root.get());
     
154. viewer->setSceneData(root.get());
     
155. viewer->addEventHandler(new UseEventHandler(pat,animationPath,pat1));
     
156. viewer->realize();
     
157. viewer->run();
     
158. return 0;
     
159. }
     

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FlySky

您可以使用osgUtil:ineSegmentIntersector获取位置信息，另外，发帖时请给出精简代码，勿全部贴出，相信很少有人能够全部仔细查看您的代码

碧潭

前49行可以不用看，是创建路径用的，给出的目的是怕碰撞检测时的位置可能和路径的设置有关系，所以才给出的，不好意思了。还请大侠们看看一直检测碰撞都为true是怎么回事

碧潭

可不可以告诉我，如果检测碰撞为true时，怎么得到和场景中哪个物体发生碰撞了

FlySky

参考osgpick，通过nodepath直接得到节点

碧潭

osgpick好像用的是LineSegmentIntersector，我只能得到起始位置的Vec3的值，而computeIntersections要的是起点和终点的double值，这该怎么办？
我用的是IntersectVisitor，这个有没有可以得到碰撞节点的方法？

array

请使用IntersectionVisitor，直接设置setStart和setEnd为您需要的起终点

碧潭

碰撞检测的代码这样改了以后，射线的起点是物体的包围球的中心，终点是物体包围球球心加上（0.0,0.0，半径），但是出现的现象是，当物体包围球的球心与地面重合时，碰撞检测才返回true，明显看到当glider进入地面一半的时候才停止，代码如下，不知道哪里没写对。

1. 
   
2. //已得到包围球bs
   
3. osg::ref_ptr<osgUtil::LineSegmentIntersector> inter=new LineSegmentIntersector(bs.center(),bs.center+osg::Vec3(0.0f,0.0f,bs.raduis());
   
4.         osg::IntersectionVisitor v(inter.get());
   
5.         gnode.accept(v);
   
6.         unsigned int size=inter->getIntersections().size();
   
7.         if(size>0){
   
8.                 Vec3 resultCoord=inter.get()->getIntersections().begin()->getWorldIntersectPoint();
   
9.       osg::Vec3 coord;
   
10.         coord[0]=resultCoord.x();
    
11.         coord[1]=resultCoord.y();
    
12.         coord[2]=resultCoord.z();
    
13.         }

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array

代码本身没有看出太多问题来，不过问题是您是否能保证您的物体就是沿着Z轴向上接触地面的

碧潭

下落的路径基本是沿Z轴下落的，在Y轴方向有个45度倾角，代码如下：

1. osg::ref_ptr<osg::AnimationPath> createAnimationPath1(osg::Vec3& pos)
   
2. {
   
3. osg::ref_ptr<osg::AnimationPath> animationPath = new osg::AnimationPath();
   
4. animationPath->setLoopMode(osg::AnimationPath::LOOP);
   
5. int numPoint = 60;
   
6. float yaw = 0.0f;
   
7. float yaw_delta = 2.0f;
   
8. float roll = osg::inDegrees(45.0f);
   
9. float time = 0.0f;
   
10. float time_delta = 0.5f;
    
11. for(int i=0;i<numPoint;i++)
    
12. {
    
13.   osg::Vec3 position(pos+osg::Vec3(0.0f,0.0f,-yaw));
    
14.   osg::Quat rotation(osg::Quat(roll,osg::Vec3(0.0,1.0,0.0)));
    
15.   animationPath->insert(time,osg::AnimationPath::ControlPoint(position,rotation));
    
16.   yaw += yaw_delta;
    
17.   time += time_delta;
    
18. }
    
19. return animationPath.get();
    
20. }

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如果这个不是沿Z轴垂直下落的，那这个检测线段该如何写，写多条吗？

碧潭

把检测线段改了一下，好了，改成

1. LineSegmentIntersector(bs.center()-osg::Vec3(0.0f,0.0fbs.raduis()),bs.center+osg::Vec3(0.0f,0.0f,bs.raduis());

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虽然可以了，但还是不明白为什么这么改就对了

array

之前的

1. bs.center(), bs.center+osg::Vec3(0.0f,0.0f,bs.raduis()

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这个起止点的意思是从中心向Z上方向发射一条线段；如果您的物体是下落的，那么显然您在这里犯了错误

zombie0606

可能你一开始设置的线段是会和大飞机相交的。