bullet 物理引擎的角色控制器(character controller)

转载 ：http://hi.baidu.com/ae8506/item/693a7975d4fd502ed6a89c56

作者:CYM  http://hi.baidu.com/ae8506/

角色控制器(character controller)是物理引擎必不可少的一部分

在bullet中可以通过btKinematicCharacterController和btPairCachingGhostObject来实现角色控制

其中btKinematicCharacterController类是致力于解决角色控制的类,他实现了滑动,爬梯子,跳跃等常见的动作.

在使用角色控制器之前先要包含以下几个文件

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1. #include <BulletDynamics\Character\btKinematicCharacterController.h>  
2. #include <BulletCollision\CollisionDispatch\btGhostObject.h>  

#include <BulletDynamics\Character\btKinematicCharacterController.h>#include <BulletCollision\CollisionDispatch\btGhostObject.h>

在头文件中声明以下两个对象

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1. btKinematicCharacterController* m_character;  
2. btPairCachingGhostObject* m_ghostObject;  

btKinematicCharacterController* m_character;btPairCachingGhostObject* m_ghostObject;

m_character就死角色控制器,m_ghostObject则是一个幽灵对象.

创建角色控制器(假设已经创建了物理世界并且可以通过physics对象调用)

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1. //创建胶囊对象以及角色控制器   
2. {  
3. m_trans.setIdentity ();  
4. m_trans.setOrigin (btVector3(0.0, 500.0, 0.0));  
5.    
6. m_ghostObject = new btPairCachingGhostObject();  
7. m_ghostObject->setWorldTransform(m_trans);  
8. physics->m_overlappingPairCache->getOverlappingPairCache()->setInternalGhostPairCallback(new btGhostPairCallback());  
9. btScalar characterHeight=2.0f;  
10. btScalar characterWidth =2.0f;  
11. btConvexShape* capsule = new btCapsuleShape(characterWidth,characterHeight);  
12. m_ghostObject->setCollisionShape (capsule);  
13. m_ghostObject->setCollisionFlags (btCollisionObject::CF_CHARACTER_OBJECT);  
14.    
15. btScalar stepHeight = btScalar(0.35);  
16. m_character = new btKinematicCharacterController (m_ghostObject,capsule,stepHeight);  
17.    
18. //向世界中添加碰撞对象   
19. physics->m_dynamicsWorld->addCollisionObject(  
20. m_ghostObject,  
21. btBroadphaseProxy::CharacterFilter,   
22. btBroadphaseProxy::StaticFilter|btBroadphaseProxy::DefaultFilter);  
23. physics->m_dynamicsWorld->addAction(m_character);  
24. }  

//创建胶囊对象以及角色控制器{m_trans.setIdentity ();m_trans.setOrigin (btVector3(0.0, 500.0, 0.0)); m_ghostObject = new btPairCachingGhostObject();m_ghostObject->setWorldTransform(m_trans);physics->m_overlappingPairCache->getOverlappingPairCache()->setInternalGhostPairCallback(new btGhostPairCallback());btScalar characterHeight=2.0f;btScalar characterWidth =2.0f;btConvexShape* capsule = new btCapsuleShape(characterWidth,characterHeight);m_ghostObject->setCollisionShape (capsule);m_ghostObject->setCollisionFlags (btCollisionObject::CF_CHARACTER_OBJECT); btScalar stepHeight = btScalar(0.35);m_character = new btKinematicCharacterController (m_ghostObject,capsule,stepHeight); //向世界中添加碰撞对象physics->m_dynamicsWorld->addCollisionObject(m_ghostObject,btBroadphaseProxy::CharacterFilter, btBroadphaseProxy::StaticFilter|btBroadphaseProxy::DefaultFilter);physics->m_dynamicsWorld->addAction(m_character);}

根据用户输入,更新角色

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1. //根据外部输入,更新角色   
2. if (m_physics->m_dynamicsWorld)  
3. {  
4. ///设置行走方向   
5. btTransform xform;  
6. xform = m_ghostObject->getWorldTransform ();  
7. //获取本地坐标向量,并且单位化   
8. btVector3 forwardDir = xform.getBasis()[2];  
9. btVector3 upDir = xform.getBasis()[1];  
10. btVector3 strafeDir = xform.getBasis()[0];  
11. forwardDir.normalize ();  
12. upDir.normalize ();  
13. strafeDir.normalize ();  
14.    
15. btVector3 walkDirection = btVector3(0.0, 0.0, 0.0);  
16. btScalar walkVelocity = btScalar(1.1) * 4.0; // 4 km/h -> 1.1 m/s  
17. btScalar walkSpeed = walkVelocity* deltaTime*2.0f;  
18.   
19. //控制前后行走,以及旋转方向,   
20. if (m_render->m_keyboard->isKeyDown(OIS::KC_RIGHT))  
21. {  
22. float yaw=0.05f;  
23. btMatrix3x3 orn = m_ghostObject->getWorldTransform().getBasis();  
24. orn *= btMatrix3x3(btQuaternion(btVector3(0,1,0),yaw));  
25. m_ghostObject->getWorldTransform ().setBasis(orn);  
26. }  
27.    
28. if (m_render->m_keyboard->isKeyDown(OIS::KC_LEFT))  
29. {  
30. float yaw=-0.05f;  
31. btMatrix3x3 orn = m_ghostObject->getWorldTransform().getBasis();  
32. orn *= btMatrix3x3(btQuaternion(btVector3(0,1,0),yaw));  
33. m_ghostObject->getWorldTransform ().setBasis(orn);  
34. }  
35.    
36. if (m_render->m_keyboard->isKeyDown(OIS::KC_UP))  
37. {  
38. walkDirection += forwardDir;  
39. }  
40.    
41. if (m_render->m_keyboard->isKeyDown(OIS::KC_DOWN))  
42. {  
43. walkDirection -= forwardDir;  
44. }  
45.    
46. if(m_render->m_keyboard->isKeyDown(OIS::KC_SPACE) && m_character && m_character->canJump())  
47. {  
48. m_character->jump();  
49. }  
50.    
51. //按照方向移动角色   
52. m_character->setWalkDirection(walkDirection*walkSpeed);  
53. }  
54.    
55. //更新渲染对象   
56. m_trans=m_ghostObject->getWorldTransform();  
57. m_node->setPosition(m_trans.getOrigin().getX(),m_trans.getOrigin().getY(),m_trans.getOrigin().getZ());  
58. m_node->setOrientation(m_trans.getRotation().getW(),m_trans.getRotation().getX(),m_trans.getRotation().getY(),m_trans.getRotation().getZ());  

//根据外部输入,更新角色if (m_physics->m_dynamicsWorld){///设置行走方向btTransform xform;xform = m_ghostObject->getWorldTransform ();//获取本地坐标向量,并且单位化btVector3 forwardDir = xform.getBasis()[2];btVector3 upDir = xform.getBasis()[1];btVector3 strafeDir = xform.getBasis()[0];forwardDir.normalize ();upDir.normalize ();strafeDir.normalize (); btVector3 walkDirection = btVector3(0.0, 0.0, 0.0);btScalar walkVelocity = btScalar(1.1) * 4.0; // 4 km/h -> 1.1 m/sbtScalar walkSpeed = walkVelocity* deltaTime*2.0f;//控制前后行走,以及旋转方向,if (m_render->m_keyboard->isKeyDown(OIS::KC_RIGHT)){float yaw=0.05f;btMatrix3x3 orn = m_ghostObject->getWorldTransform().getBasis();orn *= btMatrix3x3(btQuaternion(btVector3(0,1,0),yaw));m_ghostObject->getWorldTransform ().setBasis(orn);} if (m_render->m_keyboard->isKeyDown(OIS::KC_LEFT)){float yaw=-0.05f;btMatrix3x3 orn = m_ghostObject->getWorldTransform().getBasis();orn *= btMatrix3x3(btQuaternion(btVector3(0,1,0),yaw));m_ghostObject->getWorldTransform ().setBasis(orn);} if (m_render->m_keyboard->isKeyDown(OIS::KC_UP)){walkDirection += forwardDir;} if (m_render->m_keyboard->isKeyDown(OIS::KC_DOWN)){walkDirection -= forwardDir;} if(m_render->m_keyboard->isKeyDown(OIS::KC_SPACE) && m_character && m_character->canJump()){m_character->jump();} //按照方向移动角色m_character->setWalkDirection(walkDirection*walkSpeed);} //更新渲染对象m_trans=m_ghostObject->getWorldTransform();m_node->setPosition(m_trans.getOrigin().getX(),m_trans.getOrigin().getY(),m_trans.getOrigin().getZ());m_node->setOrientation(m_trans.getRotation().getW(),m_trans.getRotation().getX(),m_trans.getRotation().getY(),m_trans.getRotation().getZ());

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