如何取消透视

Sailent

载入地形后，用DriveManipulator漫游器进行浏览，从坡下往坡上走会发生透视的问题（即视角会“穿过”地面）。应如何解决？例如以下代码：

1. int _tmain(int argc, _TCHAR* argv[])
   
2. {
   
3.         osg::ref_ptr<osg::Group> rootnode = new osg::Group;
   
4.         osg::ref_ptr<osg::Node> loadedModel = osgDB::readNodeFile("lz.osg");
   
5.         rootnode->addChild( loadedModel.get() );
   
6.         osgViewer::Viewer viewer;
   
7.         viewer.setSceneData(rootnode.get());
   
8.         const osg::BoundingSphere& boundingSphere=loadedModel->getBound();
   
9.         osg ::ref_ptr<osgGA::DriveManipulator> trm= new osgGA::DriveManipulator;
   
10.         trm->setHomePosition(boundingSphere._center+osg::Vec3( 0.0,-3.5f * boundingSphere._radius+2000.0f,0.0f),boundingSphere._center+osg::Vec3(0.0f,0.0f,0.0f),osg::Vec3(0.0f,0.0f,1.0f));
    
11.         viewer.setCameraManipulator(trm.get());
    
12.         while (!viewer.done())
    
13.         {
    
14.                 viewer.frame();
    
15.         }
    
16.         return 0;
    
17. }

复制代码

请各位帮帮忙啊~~先谢过了~

array

可以自己继承DriveManipulator，重写一个漫游器，以实现诸如碰撞检测，以及上坡时抬升摄像机角度等工作，OSG自带的漫游器不会提供那么复杂的功能

FlySky

自己写一个操作器就可以了，， 关于碰撞检测的算法，可以参考小车爬坡，，最简单的就是线与模型相交检测～～～～～～～～

Sailent

原帖由 FlySky 于 2008-8-27 16:58 发表

自己写一个操作器就可以了，， 关于碰撞检测的算法，可以参考小车爬坡，，最简单的就是线与模型相交检测～～～～～～～～

小车爬坡的例子是哪个啊？在哪能找到啊？

FlySky

1. 小车爬坡碰撞~~~~~
   
2. 
   
3. void PopManipulator::computeHomePosition()
   
4. {
   
5. if(_node.get())
   
6. {
   
7. const osg::BoundingSphere& boundingSphere=_node->getBound();
   
8. 
   
9. osg::Vec3d ep = boundingSphere._center;
   
10. osg::Vec3d bp = ep;
    
11. 
    
12. osg::CoordinateFrame cf=getCoordinateFrame(ep);
    
13. 
    
14. ep -= getUpVector(cf)* _modelScale*0.0001;
    
15. bp -= getUpVector(cf)* _modelScale;
    
16. 
    
17. // check to see if any obstruction in front.
    
18. osgUtil::IntersectVisitor iv;
    
19. iv.setTraversalMask(_intersectTraversalMask);
    
20. 
    
21. bool positionSet = false;
    
22. 
    
23. osg::ref_ptr<osg::LineSegment> segDown = new osg::LineSegment;
    
24. segDown->set(ep,bp);
    
25. iv.addLineSegment(segDown.get());
    
26. 
    
27. _node->accept(iv);
    
28. 
    
29. if (iv.hits())
    
30. {
    
31. osgUtil::IntersectVisitor::HitList& hitList = iv.getHitList(segDown.get());
    
32. if (!hitList.empty())
    
33. {
    
34. // notify(INFO) << "Hit terrain ok"<< std::endl;
    
35. osg::Vec3d ip = hitList.front().getWorldIntersectPoint();
    
36. osg::Vec3d np = hitList.front().getWorldIntersectNormal();
    
37. 
    
38. osg::Vec3d uv;
    
39. if (np * getUpVector(cf)>0.0) uv = np;
    
40. else uv = -np;
    
41. 
    
42. ep = ip;
    
43. ep += getUpVector(cf)*_height;
    
44. osg::Vec3 lv = uv^osg::Vec3d(1.0,0.0,0.0);
    
45. 
    
46. setHomePosition(ep,ep+lv,uv);
    
47. 
    
48. positionSet = true;
    
49. 
    
50. }
    
51. 
    
52. }
    
53. 
    
54. if (!positionSet)
    
55. {
    
56. bp = ep;
    
57. bp += getUpVector(cf)*_modelScale;
    
58. 
    
59. osg::ref_ptr<osg::LineSegment> segUp = new osg::LineSegment;
    
60. segUp->set(ep,bp);
    
61. iv.addLineSegment(segUp.get());
    
62. 
    
63. _node->accept(iv);
    
64. 
    
65. if (iv.hits())
    
66. {
    
67. osgUtil::IntersectVisitor::HitList& hitList = iv.getHitList(segUp.get());
    
68. if (!hitList.empty())
    
69. {
    
70. // notify(INFO) << "Hit terrain ok"<< std::endl;
    
71. osg::Vec3d ip = hitList.front().getWorldIntersectPoint();
    
72. osg::Vec3d np = hitList.front().getWorldIntersectNormal();
    
73. 
    
74. osg::Vec3d uv;
    
75. if (np*getUpVector(cf)>0.0) uv = np;
    
76. else uv = -np;
    
77. 
    
78. ep = ip;
    
79. ep += getUpVector(cf)*_height;
    
80. osg::Vec3 lv = uv^osg::Vec3d(1.0,0.0,0.0);
    
81. setHomePosition(ep,ep+lv,uv);
    
82. 
    
83. positionSet = true;
    
84. 
    
85. }
    
86. 
    
87. }
    
88. }
    
89. 
    
90. if (!positionSet)
    
91. {
    
92. setHomePosition(
    
93. boundingSphere._center+osg::Vec3d( 0.0,-2.0 * boundingSphere._radius,0.0),
    
94. boundingSphere._center+osg::Vec3d( 0.0,-2.0 * boundingSphere._radius,0.0)+osg::Vec3d(0.0,1.0,0.0),
    
95. osg::Vec3d(0.0,0.0,1.0));
    
96. }
    
97. 
    
98. }
    
99. }

复制代码

Sailent

osg::Vec3 lv = uv^osg::Vec3d(1.0,0.0,0.0);是什么意思啊？对象还能异或？

array

原帖由 Sailent 于 2008-8-28 12:34 发表
osg::Vec3 lv = uv^osg::Vec3d(1.0,0.0,0.0);是什么意思啊？对象还能异或？

^ 表示叉乘
* 表示点乘
请仔细阅读OSG的API文档

Sailent

原帖由 array 于 2008-8-28 13:57 发表


^ 表示叉乘
* 表示点乘
请仔细阅读OSG的API文档

谢谢啦~~~OSG的API文档哪有啊？

array

原帖由 Sailent 于 2008-8-28 15:31 发表


谢谢啦~~~OSG的API文档哪有啊？

这一页就有……
http://bbs.osgchina.org/viewthread.php?tid=491

本站（包括文件中转站）其实是一个非常大的OSG资源集散地，教程、示例代码、安装包、文档……很多问题没必要挠头的，仔细找找就会有收获了