• Advertisement
Sign in to follow this  

Rotating Sphere with Euler integration

This topic is 1801 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi everyone. I'm doing my class project and i'm having troubles with Euler integration (witch seems to be the basic)...
The main loop:
 
 
        torque = position.cross(force);
        
        momentum += dt * force;
        //velocity = momentum * (1.0f / mass);
 
        position += velocity * dt;
 
        ang_momentum += torque * dt;
        m_inertia_inverse = MakeMatrixFromQuaternion(orientation).transpose() * g_inertia * MakeMatrixFromQuaternion(orientation);
        ang_vel = multvm(ang_momentum, m_inertia_inverse); //multiplies a vector by a matrix
 
        orientation += (Quaternion(0, ang_vel.x, ang_vel.y, ang_vel.z) * orientation) * (0.5f * dt);
        orientation.normalize();

 

"g_inertia" is the following matrix3

 

Ix = Iy = Iz = 0.4f * mass * Mathematics::sqrt(radius);
 
        inertia.m11 = Ix;            inertia.m12 = 0;        inertia.m13 = 0;
        inertia.m21 = 0;            inertia.m22 = Iy;        inertia.m23 = 0;

        inertia.m31 = 0;            inertia.m32 = 0;        inertia.m33 = Iz; 

 

and i'm rotating like this:

 

 

orientation.angleAxis(angle, axis); //quaternion to angle axis
    
        glTranslatef(position.x, position.y, position.z);
        glRotatef( angle / Mathematics::pi * 180.0f, axis.x, axis.y, axis.z );

 

The code is right?

Seems like i'm having trouble with the numbers. They out of range... especially with the angular velocity!

Edited by irlanrobson

Share this post


Link to post
Share on other sites
Advertisement

m_inertia_inverse = MakeMatrixFromQuaternion(orientation).transpose() * g_inertia * MakeMatrixFromQuaternion(orientation);

 

 

Would this work?

 

m_inertia_inverse = MakeMatrixFromQuaternion(orientation).transpose() * g_inertia.Inverse() * MakeMatrixFromQuaternion(orientation);

Share this post


Link to post
Share on other sites

m_inertia_inverse = MakeMatrixFromQuaternion(orientation).transpose() * g_inertia * MakeMatrixFromQuaternion(orientation);

 

 

Would this work?

 

m_inertia_inverse = MakeMatrixFromQuaternion(orientation).transpose() * g_inertia.Inverse() * MakeMatrixFromQuaternion(orientation);

thanks but i've already done this in the constructor 

Share this post


Link to post
Share on other sites

  torque = position.cross(force);

 

 

 

What about:

 

r           =  some point on sphere  -  sphere position;

 

torque  =  r.cross( force );

Share this post


Link to post
Share on other sites

  torque = position.cross(force);

 

 

 

What about:

 

r           =  some point on sphere  -  sphere position;

 

torque  =  r.cross( force );

thanks but the only force that actually i have, is the gravity force that is on the constructor ,,, 

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement