[ODE] dJointGetHinge2Angle2

[LR]

It seems to not work every case ....


I'm changing method, using univesal method (as you said) and it is really
better (i did non found any bad cases at this time...) i continue testing
before posting.

LR 

-----Message d'origine-----
De : Remi Ricard [mailto:remi.ricard at simlog.com] 
Envoyé : vendredi 4 mai 2007 16:27
À : LR; ODE Mailing List (E-mail)
Objet : Re: [ODE] dJointGetHinge2Angle2

Hi,

I will take a look and make some test.

Remi
> Great idea, i've made the folowing modifications:
>
>
> 1] In joint.cpp,
>
> ** ADDED:
> dReal dJointGetHinge2Angle2 (dJointID j) {
>   dxJointHinge2* joint = (dxJointHinge2*)j;
>   dAASSERT(joint);
>   dUASSERT(joint->vtable == &__dhinge2_vtable,"joint is not a hinge2");
>   if (joint->node[0].body) {
>     dReal ang = getHingeAngle
> (joint->node[0].body,joint->node[1].body,joint->axis1,
> 			  joint->qrel);
> 	if (joint->flags & dJOINT_REVERSE)
> 	   return -ang;
> 	else
> 	   return ang;
>   }
>   else return 0;
> }
>
> ** ADDED
> static void hinge2ComputeInitialRelativeRotation (dxJointHinge2 
> *joint) {
>   if (joint->node[0].body) {
>     if (joint->node[1].body) {
>       dQMultiply1
> (joint->qrel,joint->node[0].body->q,joint->node[1].body->q);
>     }
>     else {
>       // set joint->qrel to the transpose of the first body q
>       joint->qrel[0] = joint->node[0].body->q[0];
>       for (int i=1; i<4; i++) joint->qrel[i] = -joint->node[0].body->q[i];
>     }
>   }
> }
>
> ** IN static void makeHinge2V1andV2 (dxJointHinge2 *joint), Added 
> hinge2ComputeInitialRelativeRotation(joint); at the end of the IF() 
> code
>
>
> 2] In ojects.h
>
> ** ADDED
> ODE_API dReal dJointGetHinge2Angle2 (dJointID);
>
>
> 3] In Joint.h
> ** ADDED dQuaternion qrel;	at the end of struct dxJointHinge2 : public
> dxJoint structure
>
> It seems to work fine in my simulation but ... It may be checked by 
> someone who know how to add to vectors :))
>
> LR
>
> -----Message d'origine-----
> De : ode-bounces at ode.org [mailto:ode-bounces at ode.org] De la part de 
> Remi Ricard Envoyé : jeudi 3 mai 2007 16:47 À : ODE Mailing List 
> (E-mail) Objet : Re: [ODE] dJointGetHinge2Angle2
>
> Hi,
>
>  > In the hinge2 code we can see:
>  >
>  > static dReal measureHinge2Angle (dxJointHinge2 *joint)  > {
>  >   dVector3 a1,a2;
>  >   dMULTIPLY0_331 (a1,joint->node[1].body->posr.R,joint->axis2);
>  >   dMULTIPLY1_331 (a2,joint->node[0].body->posr.R,a1);
>  >   dReal x = dDOT(joint->v1,a2);
>  >   dReal y = dDOT(joint->v2,a2);
>  >   return -dAtan2 (y,x);
>  > }
>  >
>  > This code is called to know the vertical axis angle. Does someone 
> know how to get the angle of the horizontal axis ?
>  >
>  > I saw in the archive mails that it is a recurent question ... then 
> if someone know how to do it will help a lot of ode users :)
>
>
> I took a look in the code and there is no information of the relative 
> orientation of Body1 and Body2 along the horizontal axis.
>
> Other joint have a Quaternion (qrel) to keep the initial difference in 
> orientation but the Hinge2 uses 2 vectors to help retrieve the 
> vertical angle.
>
> If you replace those 2 vectors by a qrel you should be able to find 
> both angles.
>
> You can look at the Universal joint to implement the code.
>
> Remi
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