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#ifndef BU_Joint_H
#define BU_Joint_H
class RigidBody;
class BU_Joint;
#include "SimdScalar.h"
struct BU_ContactJointNode {
BU_Joint *joint; // pointer to enclosing BU_Joint object
RigidBody*body; // *other* body this joint is connected to
};
typedef SimdScalar dVector3[4];
class BU_Joint {
public:
// naming convention: the "first" body this is connected to is node[0].body,
// and the "second" body is node[1].body. if this joint is only connected
// to one body then the second body is 0.
// info returned by getInfo1 function. the constraint dimension is m (<=6).
// i.e. that is the total number of rows in the jacobian. `nub' is the
// number of unbounded variables (which have lo,hi = -/+ infinity).
BU_Joint();
virtual ~BU_Joint();
struct Info1 {
int m,nub;
};
// info returned by getInfo2 function
struct Info2 {
// integrator parameters: frames per second (1/stepsize), default error
// reduction parameter (0..1).
SimdScalar fps,erp;
// for the first and second body, pointers to two (linear and angular)
// n*3 jacobian sub matrices, stored by rows. these matrices will have
// been initialized to 0 on entry. if the second body is zero then the
// J2xx pointers may be 0.
SimdScalar *J1l,*J1a,*J2l,*J2a;
// elements to jump from one row to the next in J's
int rowskip;
// right hand sides of the equation J*v = c + cfm * lambda. cfm is the
// "constraint force mixing" vector. c is set to zero on entry, cfm is
// set to a constant value (typically very small or zero) value on entry.
SimdScalar *c,*cfm;
// lo and hi limits for variables (set to -/+ infinity on entry).
SimdScalar *lo,*hi;
// findex vector for variables. see the LCP solver interface for a
// description of what this does. this is set to -1 on entry.
// note that the returned indexes are relative to the first index of
// the constraint.
int *findex;
};
// virtual function table: size of the joint structure, function pointers.
// we do it this way instead of using C++ virtual functions because
// sometimes we need to allocate joints ourself within a memory pool.
virtual void GetInfo1 (Info1 *info)=0;
virtual void GetInfo2 (Info2 *info)=0;
int flags; // dJOINT_xxx flags
BU_ContactJointNode node[2]; // connections to bodies. node[1].body can be 0
SimdScalar lambda[6]; // lambda generated by last step
};
#endif //BU_Joint_H
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