a b-spline animator
Posted: Tue Jul 03, 2007 5:31 am
I'm working on a spline editor :
http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=22559
But in some case I was not totally satisfied of the spline created with createFollowSplineAnimator because the start of the spline is influenced by the last point position :
I created a new spline animator based on a b-spline, the difference are :
- the start is not influenced by the end
- the controls points are not on the spline but outside (easy to edit with my editor
)
- the node doesn't slow on curve points
- at the end of the spline the node jump instantaneously at the start. (maybe it will be usefull to add an option to run only once and add a self removing animator with the vitek's functions )
i've add too a feature to rotate the node animated by this for always look forward facing the spline
the code (based on the Rob Bateman opengl exemple of b-spline) :
exmple for use :
http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=22559
But in some case I was not totally satisfied of the spline created with createFollowSplineAnimator because the start of the spline is influenced by the last point position :
I created a new spline animator based on a b-spline, the difference are :
- the start is not influenced by the end
- the controls points are not on the spline but outside (easy to edit with my editor
)- the node doesn't slow on curve points
- at the end of the spline the node jump instantaneously at the start. (maybe it will be usefull to add an option to run only once and add a self removing animator with the vitek's functions )
i've add too a feature to rotate the node animated by this for always look forward facing the spline
the code (based on the Rob Bateman opengl exemple of b-spline) :
Code: Select all
class CBSplineAnimator : public ISceneNodeAnimator
{
public:
CBSplineAnimator(u32 time, core::array<core::vector3df> points, f32 speed = 1.0f);
virtual ~CBSplineAnimator ();
virtual void animateNode (scene::ISceneNode *node, u32 timeMs);
protected:
int clamp(s32 idx, u32 size);
core::array<core::vector3df> mPoints;
u32 mStartTime;
f32 mSpeed;
};
CBSplineAnimator::CBSplineAnimator(u32 time, core::array<core::vector3df> points, f32 speed)
{
mStartTime = time;
mPoints = points;
mSpeed = speed;
}
CBSplineAnimator::~CBSplineAnimator ()
{
}
inline int CBSplineAnimator::clamp(s32 idx, u32 size)
{
return ( idx<0 ? 0 : ( idx>=size ? size-1 : idx ) );
}
void CBSplineAnimator::animateNode (scene::ISceneNode *node, u32 timeMs)
{
u32 pSize = mPoints.size();
const f32 dt = ( (timeMs-mStartTime) * mSpeed * 0.001f );
const f32 u = core::fract ( dt );
s32 idx = core::floor32( dt ) % (pSize+1);
f32 iu = 1.0f-u;
float b0 = iu * iu * iu / 6.0f;
float b1 = ( 3 * u * u * u - 6 * u * u + 4 ) / 6.0f;
float b2 = (-3 * u * u * u + 3 * u * u + 3* u + 1 ) /6.0f;
float b3 = u * u * u /6.0f;
core::vector3df f, p0, p1, p2, p3;
p0 = mPoints[ clamp( idx-2, pSize ) ];
p1 = mPoints[ clamp( idx-1, pSize ) ];
p2 = mPoints[ clamp( idx+0, pSize ) ];
p3 = mPoints[ clamp( idx+1, pSize ) ];
f = b0 * p0 + b1 * p1 + b2 * p2 + b3 * p3;
// set node orientation
core::vector3df direction = node->getPosition() - f;
node->setRotation(direction.getHorizontalAngle());
// set node position
node->setPosition(f);
}
Code: Select all
CBSplineAnimator *anim = new CBSplineAnimator(device->getTimer()->getTime(), points, 4.0f);
cubeNode->addAnimator((scene::ISceneNodeAnimator*)anim);
