Bullet + ogre mouse moving object

[Runemaster]

Hi everyone! In my project I'm using Ogre + bullet and is now realizing the manipulation of the object with the mouse. My problem is as follows:

Quest 2.jpg

Code for moving object:

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void TestComponet::move(const Ogre::Vector2& currentMousePosition, const Ogre::Vector2& oldMousePosition)
{
    Ogre::Ray ray = camera_->getCameraToViewportRay(currentMousePosition.x, currentMousePosition.y);
    Ogre::Vector3 objectPosition = cvt(collisionObject_->getWorldTransform().getOrigin()); // cvt function convert bullet to ogre and ogre to bullet (vectors, quaternions)
    Ogre::Real a = (objectPosition - ray.getOrigin()).length();
    Ogre::Real b = (currentMousePosition - oldMousePosition).length();
    Ogre::Real distance = sqrt(a*a + b*b);
    Ogre::Vector3 newPosition = ray.getPoint(distance);

    btTransform tr = collisionObject_->getWorldTransform();
    tr.setOrigin(cvt(newPosition));
    collisionObject_->setWorldTransform(tr);
    entityNode_->setPosition(newPosition);
}

Code for raycast object this:

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void RenderWidget::_mouseRaycast(Ogre::Real x, Ogre::Real y)
{
    Ogre::Ray     ray  = camera_->getCameraToViewportRay(x, y);
    Ogre::Vector3 dest = ray.getPoint(FAR_CLIP_DISTANCE);

    btVector3 rayFrom, rayTo;

    rayFrom            = cvt(ray.getOrigin());
    rayTo              = cvt(dest);

    btCollisionWorld::ClosestRayResultCallback rayResultCallBack(rayFrom, rayTo);
    collisionWorld_->rayTest(rayFrom, rayTo, rayResultCallBack);

    if(rayResultCallBack.hasHit())
    {
        for(register int i = 0; i < SCROLLAREA_CONTENT_COUNT; i++)
        {
            if(components_[i]->isThisObject(rayResultCallBack.m_collisionObject))
            {
                if(activeComponent_ != components_[i])
                {
                    prevActiveComponent_     = activeComponent_;
                    activeComponent_         = components_[i];
                    activeComponent_->setPickPosition(rayResultCallBack.m_hitPointWorld);
                    isActiveComponentChange_ = true;
                }
                else { isActiveComponentChange_ = false; activeComponent_->setPickPosition(rayResultCallBack.m_hitPointWorld); }

                return;
            }
        }
    }
    else
    {
        prevActiveComponent_     = activeComponent_;
        activeComponent_         = false;
        isActiveComponentChange_ = true;
    }
}

P.S. Thank you

[dphil]

This part of your code:

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btTransform tr = collisionObject_->getWorldTransform();
tr.setOrigin(cvt(newPosition));
collisionObject_->setWorldTransform(tr);
entityNode_->setPosition(newPosition);

will always just move the centre (origin) of your object to the new mouse location, disregarding exactly where on the object you originally clicked. Instead, you'd want to do something like:

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Ogre::Vector3 objectoffset = ...; // vector from the clicked point on your object (in world space) to the centre of the object (its original world origin) projected on the viewing plane so we ignore depth and just get the lateral offset
btTransform tr = collisionObject_->getWorldTransform();
tr.setOrigin(cvt(newPosition + objectOffset)); // add offset here
collisionObject_->setWorldTransform(tr);
entityNode_->setPosition(newPosition);

I'm not sure the best way you want to get the objectOffset vector, but anyway the point is just to make an extra translation to account for the offset of the click from the object centre.

[Runemaster]

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Ogre::Vector3 offset = cvt(getPickPosition()) - objectPosition;

When I look forward bias, the object is moving at "twitch", that I am doing wrong?
Thank you.