public Point3d calcCenterOfRotation() {
List<Integer> line = getLongestLayerLine();
// can't determine center of rotation if there are only 2 points
// TODO does this ever happen??
if (line.size() < 3) {
return subunits.getCentroid();
}
Point3d centerOfRotation = new Point3d();
List<Point3d> centers = subunits.getOriginalCenters();
// calculate helix mid points for each set of 3 adjacent subunits
for (int i = 0; i < line.size() - 2; i++) {
Point3d p1 = new Point3d(centers.get(line.get(i)));
Point3d p2 = new Point3d(centers.get(line.get(i + 1)));
Point3d p3 = new Point3d(centers.get(line.get(i + 2)));
transformationMatrix.transform(p1);
transformationMatrix.transform(p2);
transformationMatrix.transform(p3);
centerOfRotation.add(getMidPoint(p1, p2, p3));
}
// average over all midpoints to find best center of rotation
centerOfRotation.scale(1 / (line.size() - 2));
// since helix is aligned along the y-axis, with an origin at y = 0, place the center of
// rotation there
centerOfRotation.y = 0;
// transform center of rotation to the original coordinate frame
reverseTransformationMatrix.transform(centerOfRotation);
// System.out.println("center of rotation: " + centerOfRotation);
return centerOfRotation;
}
/**
* Calculates the min and max boundaries of the structure after it has been transformed into its
* canonical orientation.
*/
private void calcBoundaries() {
minBoundary.x = Double.MAX_VALUE;
maxBoundary.x = Double.MIN_VALUE;
minBoundary.y = Double.MAX_VALUE;
maxBoundary.x = Double.MIN_VALUE;
minBoundary.z = Double.MAX_VALUE;
maxBoundary.z = Double.MIN_VALUE;
xzRadiusMax = Double.MIN_VALUE;
Point3d probe = new Point3d();
for (Point3d[] list : subunits.getTraces()) {
for (Point3d p : list) {
probe.set(p);
transformationMatrix.transform(probe);
minBoundary.x = Math.min(minBoundary.x, probe.x);
maxBoundary.x = Math.max(maxBoundary.x, probe.x);
minBoundary.y = Math.min(minBoundary.y, probe.y);
maxBoundary.y = Math.max(maxBoundary.y, probe.y);
minBoundary.z = Math.min(minBoundary.z, probe.z);
maxBoundary.z = Math.max(maxBoundary.z, probe.z);
xzRadiusMax = Math.max(xzRadiusMax, Math.sqrt(probe.x * probe.x + probe.z * probe.z));
}
}
// System.out.println("MinBoundary: " + minBoundary);
// System.out.println("MaxBoundary: " + maxBoundary);
// System.out.println("zxRadius: " + xzRadiusMax);
}
private double[] getSubunitZDepth() {
int n = subunits.getSubunitCount();
double[] depth = new double[n];
Point3d probe = new Point3d();
// transform subunit centers into z-aligned position and calculate
// z-coordinates (depth) along the z-axis.
for (int i = 0; i < n; i++) {
Point3d p = subunits.getCenters().get(i);
probe.set(p);
transformationMatrix.transform(probe);
depth[i] = probe.z;
}
return depth;
}
/* (non-Javadoc)
* @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getGeometricCenter()
*/
@Override
public Point3d getGeometricCenter() {
run();
Point3d geometricCenter = new Point3d();
Vector3d translation = new Vector3d();
// reverseTransformationMatrix.get(translation);
// TODO does this apply to the helic case?
// calculate adjustment around z-axis and transform adjustment to
// original coordinate frame with the reverse transformation
// Vector3d corr = new Vector3d(0,minBoundary.y+getDimension().y, 0);
// reverseTransformationMatrix.transform(corr);
// geometricCenter.set(corr);
reverseTransformationMatrix.transform(translation);
geometricCenter.add(translation);
return geometricCenter;
}
/**
* Returns a transformation matrix that rotates refPoints to match coordPoints
*
* @param refPoints the points to be aligned
* @param referenceVectors
* @return
*/
private Matrix4d alignAxes(Vector3d[] axisVectors, Vector3d[] referenceVectors) {
Matrix4d m1 = new Matrix4d();
AxisAngle4d a = new AxisAngle4d();
Vector3d axis = new Vector3d();
// calculate rotation matrix to rotate refPoints[0] into coordPoints[0]
Vector3d v1 = new Vector3d(axisVectors[0]);
Vector3d v2 = new Vector3d(referenceVectors[0]);
double dot = v1.dot(v2);
if (Math.abs(dot) < 0.999) {
axis.cross(v1, v2);
axis.normalize();
a.set(axis, v1.angle(v2));
m1.set(a);
// make sure matrix element m33 is 1.0. It's 0 on Linux.
m1.setElement(3, 3, 1.0);
} else if (dot > 0) {
// parallel axis, nothing to do -> identity matrix
m1.setIdentity();
} else if (dot < 0) {
// anti-parallel axis, flip around x-axis
m1.set(flipX());
}
// apply transformation matrix to all refPoints
m1.transform(axisVectors[0]);
m1.transform(axisVectors[1]);
// calculate rotation matrix to rotate refPoints[1] into coordPoints[1]
v1 = new Vector3d(axisVectors[1]);
v2 = new Vector3d(referenceVectors[1]);
Matrix4d m2 = new Matrix4d();
dot = v1.dot(v2);
if (Math.abs(dot) < 0.999) {
axis.cross(v1, v2);
axis.normalize();
a.set(axis, v1.angle(v2));
m2.set(a);
// make sure matrix element m33 is 1.0. It's 0 on Linux.
m2.setElement(3, 3, 1.0);
} else if (dot > 0) {
// parallel axis, nothing to do -> identity matrix
m2.setIdentity();
} else if (dot < 0) {
// anti-parallel axis, flip around z-axis
m2.set(flipZ());
}
// apply transformation matrix to all refPoints
m2.transform(axisVectors[0]);
m2.transform(axisVectors[1]);
// combine the two rotation matrices
m2.mul(m1);
// the RMSD should be close to zero
Point3d[] axes = new Point3d[2];
axes[0] = new Point3d(axisVectors[0]);
axes[1] = new Point3d(axisVectors[1]);
Point3d[] ref = new Point3d[2];
ref[0] = new Point3d(referenceVectors[0]);
ref[1] = new Point3d(referenceVectors[1]);
if (SuperPosition.rmsd(axes, ref) > 0.1) {
System.out.println(
"Warning: AxisTransformation: axes alignment is off. RMSD: "
+ SuperPosition.rmsd(axes, ref));
}
return m2;
}
