/**
* Computes the new transform for this interpolator for a given alpha value.
*
* @param alphaValue alpha value between 0.0 and 1.0
* @param transform object that receives the computed transform for the specified alpha value
* @since Java 3D 1.3
*/
public void computeTransform(float alphaValue, Matrix4f transform) {
transform.loadIdentity();
// compute the current value of u from alpha and the
// determine lower and upper knot points
computePathInterpolation(alphaValue);
// Determine the segment within which we will be interpolating
currentSegmentIndex = this.lowerKnot - 1;
// if we are at the start of the curve
if (currentSegmentIndex == 0 && currentU == 0f) {
iQuat.set(keyFrames[1].quat);
iPos.set(keyFrames[1].position);
iScale.set(keyFrames[1].scale);
// if we are at the end of the curve
} else if (currentSegmentIndex == (numSegments - 1) && currentU == 1.0) {
iQuat.set(keyFrames[upperKnot].quat);
iPos.set(keyFrames[upperKnot].position);
iScale.set(keyFrames[upperKnot].scale);
// if we are somewhere in between the curve
} else {
// Get a reference to the current spline segment i.e. the
// one bounded by lowerKnot and upperKnot
currentSegment = cubicSplineCurve.getSegment(currentSegmentIndex);
// interpolate quaternions
currentSegment.getInterpolatedQuaternion(currentU, iQuat);
// interpolate position
currentSegment.getInterpolatedPositionVector(currentU, iPos);
// interpolate position
currentSegment.getInterpolatedScale(currentU, iScale);
}
// Alway normalize the quaternion
iQuat.normalize();
iQuat.toRotationMatrix(tMat);
// Set the translation components.
tMat.m03 = iPos.x;
tMat.m13 = iPos.y;
tMat.m23 = iPos.z;
rotation.set(tMat);
// construct a Transform3D from: axis * rotation * axisInverse
// transform.multLocal(axis);
transform.multLocal(rotation);
transform.scale(new Vector3f(iScale));
// transform.multLocal(axisInverse);
}
