Manual movement and rotating

[Aldeminor]

Ok. we have newton body, we can push it by forces and rotate by torques. But how to set body's position manualy in x,y,z and turn it on required angle? Is it NewtonBodyGetMatrix and NewtonBodySetMatrix for movement? How to use it and how to set angle of turn?
Also will be good to know, how to return body's position and angles.

(I know, its a stupid questions about very basic things, but... our programmer realy break his head about this wall of code )

[Stucuk]

Using the NewtonBodySetMatrix for actual movement of an object should cause Errors in your simulation. Its only really meant for placing objects.

[Julio Jerez]

you can use NewtonBodyGetMatrix and NewtonBodySetMatrix
and use a function to convert a matrix to euler angles.

[Aldeminor]

If it cause errors, how to preciosly move body in certain coordinates?
And can you post code example with extracting coords and angles from matrix?

Also, NGD supports quaternions?

[Stucuk]

It should (Unless its different now) cause errors as you could move one object inside an other object, so instead of reacting like one object hit another as you would get with forces, what you should see is one object trying to get out of another object(With Newton if one object is inside another, the object tries to get back outside the object).

[Julio Jerez]

you can reard the quaternion by using void NewtonBodyGetRotation(const NewtonBody* body, dFloat* rotation);
but the only way to set a orientation is by using NewtonBodyGetMatrix

if your angles are in the form of Pitch, Yaw, Roll
meaning Pitch is a rotation around x, yaw rotation around y and roll a rotation aroung z you can use these functions

void NewtonGetEulerAngle (const dFloat* matrix, dFloat* eulersAngles);
void NewtonSetEulerAngle (const dFloat* eulersAngles, dFloat* matrix);

if you use a different order for angle, you will need to get some info on matrix and euler angle from Mathworld or some other place in the net.

you can also check the dMatrix class in newton SDK, it comes with plenty functions for converting matrix to angles, quaternion to angles,
get scale, shear and all kind of opertions on transformation matrices.

[kallaspriit]

I think he mean positioning the body in a way that correctly interacts with the world, I guess to IK joint would be the right tool for that.

[Aldeminor]

Thanks all for reply.

I guess to IK joint would be the right tool for that.

Can you, please, explain more detail about? What is IK?

[kallaspriit]

CustomKinematicController NGD custom joint has methods like:

Code: Select all

void SetTargetRotation (const dQuaternion& rotation);
void SetTargetPosit (const dVector& posit);
void SetTargetMatrix (const dMatrix& matrix);

This tries to move and orient a body to given position-orientation by applying appropriate forces, but without exceeding some limits so if there's something in the way, it wont just penetrate it but try to push it away.