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[kluks]

Hi all. I just started experimenting with Xith3D. I want to a group of objects (a bunch of spheres at the moment) along a curve (circle would be ok for the moment). Could you point me to some examples or explain what classes should I use.

I could use TransformationDirectives and modify x,y,z speeds every few frames but this looks like a very cumbersome solution.

Regards,
Krzysztof

[Marvin Fröhlich]

Hi Krzysztof. Welcome to Xith3D .

I suggest to use org.openmali.curves.BezierCurve to compute the positions at a timepoint. Is applying them to the scenegraph a problem for you?

Marvin

[kluks]

Thanks for your reply Marvin.

I could use some help with applying computed positions to my scenegraph. I created BezierCurve2 object and I can compute points on it with getPoint() method in prepareNextFrame(). But how do I actually use them to transform scenegraph? Do I need to use DistanceInterpolator?

[Marvin Fröhlich]

No you don't have to further interpolate the translation, since it already is interpolated by BezierCurve2.

All you need to do is to get the right TransformGroup "tg" and do the following with it:

Code:

Point3f p = your_interpolated_point_on_the_bezier_curve;
tg.getTransform().setTranslation( p );
tg.updateTransform();

That's all so far. Maybe you also want to adjust the rotation, so that the shape isn't always facing in the same absolute direction. This can be done by e.g. this code:

Code:

Point3f p0 = you_center_fix_point;

...

Vector3f v = Vector3f.fromPool();
v.sub( p0, p );
float angle = v.angle( Vector3f.POSITIVE_X_AXIS );
Matrix3f rot = Matrix3f.fromPool();
MatrixUtils.getRotationMatrix( 0f, 0f, 1f, angle, rot );
tg.getTransform().setRotation( rot );
tg.getTransform().setTranslation( p );
tg.updateTransform();

Matrix3f.toPool( rot );
Vector3f.toPool( v );

Marvin

[kluks]

It works, thanks!