Am 12.08.2015 um 11:05 schrieb Elias Tarasov:
Hi!
My node which i want to rotate is a propeller, and let say it should rotate 60
times per second (60 rps).
My notebook's screen has 60Hz and i have read somewhere that this leads to call
NodeCallback::operator() 60 times per second
(for optimization reason, but it's only my assumption).
Let also say that deltaAngle is an angle i want to rotate my propeller for each
time operator() is called (60 Hz -> 60 times per second in my case).
Then for needed 60 rps i have:
Code:
deltaAngle = 2.0 * osg::Pi / (60 * 60)
rad, is that correct?
If it is, then my callback operator is:
Code:
class UpdateCallback : public NodeCallback {
public:
UpdateCallback() : angle(0.0), deltaAngle(2.0f * osg::PI / 3600.0f),
rotation() {}
virtual void operator () (Node* node, NodeVisitor* nv) {
MatrixTransform* mt = dynamic_cast<MatrixTransform*>(
node );
if ( mt != NULL ) {
if(angle < 2.0f * osg::PI)
angle += deltaAngle;
else
angle = 0.0;
rotation.makeRotate(angle, Y_AXIS);
Matrix rotate(rotation);
Matrix translate = mt->getMatrix();
Matrix setupTransAndRot = rotate * translate;
mt->setMatrix(setupTransAndRot);
}
traverse(node,nv);
}
private:
double angle;
const double deltaAngle;
Quat rotation;
};
The video of running program
https://drive.google.com/file/d/0ByDDImhSolf6SS1fREJZTG1aNDA/view?usp=sharing
displays 2 issues:
1. Somehow rotation is not linear, but instead has acceleration.
Matrix rotate(rotation);
Matrix translate = mt->getMatrix();
Matrix setupTransAndRot = rotate * translate;
-> this will effectively multiply with the previous rotation, as you are
getting the complete matrix and ADD your rotation by multiplying
Do something like:
setMatrix(mt->getTrans() * rotation);
2. It starts clockwise, but ends counter-clockwise.
Sampling artifact/aliasing. It is not turning the other direction, it
just seems to, du to the sampling rate smaller than the rotation change.
See[0]
Btw: To achieve continuous rotation, you can use osgSim::DOFTransform.
It can handle continuous rotation apart from other simulation-specific
moving
[0] https://www.youtube.com/watch?v=7_5M4fnumBw&spfreload=10
Cheers
Sebastian
Thank you!
Cheers,
Elias
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=64734#64734
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