接著上文繼續(xù)學(xué)習(xí)ode物理引擎的函數(shù)和數(shù)據(jù)結(jié)構(gòu)O(∩_∩)O~
15.剛體對(duì)象的啟用和禁止
剛體對(duì)象可以被啟用或者禁止
禁止剛體對(duì)象則在仿真過(guò)程中剛體不參與仿真
如果啟用自禁止的話,那么剛體對(duì)象會(huì)在給定仿真步中idle(如何翻譯?)
如果啟用自動(dòng)禁止的話,那么當(dāng)剛體線速度和角速度同時(shí)小于給定閾值之時(shí)被禁止
1 void dBodyEnable (dBodyID);
2 void dBodyDisable (dBodyID);
3 int dBodyIsEnabled (dBodyID);
4 void dBodySetAutoDisableFlag (dBodyID, int do_auto_disable);
5 int dBodyGetAutoDisableFlag (dBodyID);
1
void dBodySetAutoDisableAngularThreshold (dBodyID, dReal angular_threshold);
2dReal dBodyGetAutoDisableAngularThreshold (dBodyID);
3void dBodySetAutoDisableLinearThreshold (dBodyID, dReal linear_threshold);
4dReal dBodyGetAutoDisableLinearThreshold (dBodyID);
需要確保的是線速度和角速度要小于給定的閾值
16.幾個(gè)雜項(xiàng)函數(shù)
1 void dBodySetData (dBodyID, void *data);
2 void *dBodyGetData (dBodyID);
設(shè)置,和獲取剛體數(shù)據(jù)
1 int dBodyGetNumJoints (dBodyID b);
獲取關(guān)聯(lián)到物體上的關(guān)節(jié)個(gè)數(shù)
1 dJointID dBodyGetJoint (dBodyID, int index);
獲取給物體上定標(biāo)號(hào)的關(guān)節(jié)句柄
1 void dBodySetGravityMode (dBodyID b, int mode);
2 int dBodyGetGravityMode (dBodyID b);
設(shè)置和獲取物體是否受重力影響(默認(rèn)為是)
1 void dMakeRandomVector (dReal *A, int n, dReal range);
獲取n個(gè)范圍在+-rang中的隨機(jī)變量
17.矩陣操作
-- 在任何引擎中矩陣都是必不可少的
1 void dRSetIdentity (dMatrix3 R);
2 void dRFromAxisAndAngle (dMatrix3 R, dReal ax, dReal ay, dReal az,dReal angle);
3 void dRFromEulerAngles (dMatrix3 R, dReal phi, dReal theta, dReal psi);
4 void dRFrom2Axes (dMatrix3 R, dReal ax, dReal ay, dReal az,dReal bx, dReal by, dReal bz);
5 void dRFromZAxis (dMatrix3 R, dReal ax, dReal ay, dReal az);
6 void dQSetIdentity (dQuaternion q);
7 void dQFromAxisAndAngle (dQuaternion q, dReal ax, dReal ay, dReal az,dReal angle);
8 void dQMultiply0 (dQuaternion qa, const dQuaternion qb, const dQuaternion qc);
9 void dQMultiply3 (dQuaternion qa, const dQuaternion qb, const dQuaternion qc);
10 void dRfromQ (dMatrix3 R, const dQuaternion q);
11 void dQfromR (dQuaternion q, const dMatrix3 R);
12 void dDQfromW (dReal dq[4], const dVector3 w, const dQuaternion q);
這些函數(shù)為別是:
設(shè)置為單位矩陣,
從給定軸和角度或者矩陣
從歐拉角到矩陣
...
18.ode關(guān)節(jié)
1 dJointID dJointCreateBall (dWorldID, dJointGroupID);
2 dJointID dJointCreateHinge (dWorldID, dJointGroupID);
3 dJointID dJointCreateSlider (dWorldID, dJointGroupID);
4 dJointID dJointCreateContact (dWorldID, dJointGroupID,
5 const dContact *);
6 dJointID dJointCreateUniversal (dWorldID, dJointGroupID);
7 dJointID dJointCreateHinge2 (dWorldID, dJointGroupID);
8 dJointID dJointCreateFixed (dWorldID, dJointGroupID);
9 dJointID dJointCreateAMotor (dWorldID, dJointGroupID);
10 void dJointDestroy (dJointID);
可以看出ode中定義的關(guān)機(jī)類型有Ball,Hinge,Slider,...
對(duì)關(guān)節(jié)的銷(xiāo)毀動(dòng)作為斷開(kāi)所有連接的引擎物體,再銷(xiāo)毀關(guān)節(jié)
1 dJointGroupID dJointGroupCreate (int max_size);
2 void dJointGroupDestroy (dJointGroupID);
3 void dJointGroupEmpty (dJointGroupID);
4
第一個(gè)函數(shù)中的max_size目前必須是(0)這是為了和以前兼容
銷(xiāo)毀關(guān)節(jié)和清空關(guān)節(jié)點(diǎn)區(qū)別在于銷(xiāo)毀會(huì)銷(xiāo)毀關(guān)節(jié)組中所有的關(guān)節(jié)對(duì)象和銷(xiāo)毀關(guān)節(jié)組,而清空關(guān)節(jié)組則只是銷(xiāo)毀所有的關(guān)節(jié)對(duì)象
1 void dJointAttach (dJointID, dBodyID body1, dBodyID body2);
使用給定關(guān)節(jié)連接2個(gè)物理對(duì)象,如果關(guān)節(jié)先前是連接的則斷開(kāi)之,如果body1或者body2有1個(gè)為0則說(shuō)明把對(duì)象連接對(duì)靜態(tài)環(huán)境中去
1 void dJointSetData (dJointID, void *data);
2 void *dJointGetData (dJointID);
設(shè)置關(guān)節(jié)數(shù)據(jù)沒(méi)什么好說(shuō)的
1 int dJointGetType (dJointID);
獲取給定關(guān)節(jié)的關(guān)節(jié)類型
可能的類型有
dJointTypeBall A ball-and-socket joint.
dJointTypeHinge A hinge joint.
dJointTypeSlider A slider joint.
dJointTypeContact A contact joint.
dJointTypeUniversal A universal joint.
dJointTypeHinge2 A hinge-2 joint.
dJointTypeFixed A fixed joint.
dJointTypeAMotor An angular motor joint.
1 dBodyID dJointGetBody (dJointID, int index);
獲取關(guān)節(jié)給定索引的連接物理對(duì)象(以0索引起始)
1 int dAreConnected (dBodyID, dBodyID);
檢測(cè)2個(gè)問(wèn)題是不是別連接了
19.關(guān)節(jié)接觸;
ode用戶指南的原文是:
The contact joint prevents body 1 and body 2 from inter-penetrating at the contact point. It does this by
only allowing the bodies to have an "outgoing "velocity in the direction of the contact normal. Contact joints
typically have a lifetime of one time step. They are created and deleted in response to collision detection.
Contact joints can simulate friction at the contact by applying special forces in the two friction directions
that are perpendicular to the normal.When a contact joint is created, a dContact structure must be supplied. This has the following definition:
接觸關(guān)節(jié)預(yù)防碰撞對(duì)象的"刺穿"問(wèn)題,當(dāng)接觸關(guān)節(jié)產(chǎn)生的時(shí)候,其必要的數(shù)據(jù)元素必須被標(biāo)記
1 struct dContact {
2 dSurfaceParameters surface;
3 dContactGeom geom;
4 dVector3 fdir1;
5 };
goem是碰撞函數(shù)設(shè)置的數(shù)據(jù)結(jié)構(gòu)其中包含了:
碰撞點(diǎn),碰撞法向矢量和碰撞的2個(gè)對(duì)象id
而fdir是第一摩擦力方向(其方向和摩擦力方向是相同的),同時(shí)也是垂直于接觸面法向矢量的.
當(dāng)且僅當(dāng)surface.mode = dContactFDir1時(shí)期需要被定義
而第二摩擦力方向則是由第一摩擦里方向和接觸面方向矢量計(jì)算的正交向量
其中的dSurfaceParameters surface是由用戶設(shè)置的數(shù)據(jù)結(jié)構(gòu)
其數(shù)據(jù)結(jié)構(gòu)為:
1 typedef struct dSurfaceParameters {
2 /* must always be defined */
3 int mode;
4 dReal mu;
5
6 /* only defined if the corresponding flag is set in mode */
7 dReal mu2;
8 dReal bounce;
9 dReal bounce_vel;
10 dReal soft_erp;
11 dReal soft_cfm;
12 dReal motion1,motion2;
13 dReal slip1,slip2;
14 } dSurfaceParameters;
其中的mode必須被標(biāo)記
mu和mu2取值為(0 to dInfinity.)
如果沒(méi)有設(shè)置mu2,則使用mu為2個(gè)摩擦力方向
如果設(shè)置了mu2則使用mu為第一個(gè)摩擦力方向使用mu2為第二摩擦力方向
如果設(shè)置了fdir1則使用fdir作為第一摩擦力方向要不然則自動(dòng)獲取其值
bounce表明其為彈性表面也就是說(shuō)碰撞對(duì)象會(huì)相互彈起(取值0-1)0標(biāo)明完全沒(méi)有彈性
soft_erp控制的是接觸表面的erp,這個(gè)值可以設(shè)置柔性表面
soft_cfm控制的是柔性表面的最大cfm
其他參數(shù)以后再介紹之
20.幾何體對(duì)象
幾何體是檢測(cè)系統(tǒng)中的基本單元
幾何體的銷(xiāo)毀和生成
1 void dGeomDestroy (dGeomID);
2 void dGeomSetData (dGeomID, void *);
3 void *dGeomGetData (dGeomID);
4 void dGeomSetBody (dGeomID, dBodyID);
5 dBodyID dGeomGetBody (dGeomID);
6 void dGeomSetPosition (dGeomID, dReal x, dReal y, dReal z);
7 void dGeomSetRotation (dGeomID, const dMatrix3 R);
8 void dGeomSetQuaternion (dGeomID, const dQuaternion);
9 const dReal * dGeomGetPosition (dGeomID);
10 const dReal * dGeomGetRotation (dGeomID);
11 void dGeomGetQuaternion (dGeomID, dQuaternion result);
12 void dGeomGetAABB (dGeomID, dReal aabb[6]);
13 int dGeomIsSpace (dGeomID);
14 dSpaceID dGeomGetSpace (dGeomID);
其中有幾何體的銷(xiāo)毀,設(shè)置幾何體數(shù)據(jù),關(guān)聯(lián)幾何體到缸體
設(shè)置,獲取幾何體旋轉(zhuǎn),
獲取幾何體aabb盒子以及檢測(cè)幾何體是否在空間中
1 int dGeomGetClass (dGeomID);
這是獲取幾何體類型的函數(shù)其取值為:
dSphereClass Sphere
dBoxClass Box
dCCylinderClass Capped cylinder
dCylinderClass Regular flat-ended cylinder
dPlaneClass Infinite plane (non-placeable)
dGeomTransformClass Geometry transform
dRayClass Ray
dTriMeshClass Triangle mesh
dSimpleSpaceClass Simple space
dHashSpaceClass Hash table based space
int dGeomGetClass (dGeomID);
下面的是幾何體的禁止和啟用
1 void dGeomEnable (dGeomID);
2 void dGeomDisable (dGeomID);
3 int dGeomIsEnabled (dGeomID);
如果幾何體被禁止那么他就不會(huì)才與碰撞(盡管它在物理空間中)
該篇就到這里吧,這里給出一個(gè)典型的接觸面設(shè)置:
1 surface.mode = dContactBounce | dContactSoftCFM;
2 surface.mu = dInfinity;
3 surface.mu2 = 0;
4 surface.bounce = 0.01;
5 surface.bounce_vel = 0.1;
6 surface.soft_cfm = 0.01;
可以看出他是使用了接觸面彈起
其第一摩擦力方向和第二摩擦力方向是相同的