@Override
public boolean update(final int deltaTime) {
if (mNumPoints > 0) {
if (!mFollowingHead && mTarget != null) {
final PointF p1 = mTarget.getPosition();
final float dx = p1.x - (mPoints[0].x - mTargetOffset.x);
final float dy = p1.y - (mPoints[0].y - mTargetOffset.y);
if (Math.abs(dx) >= 1 || Math.abs(dy) >= 1) {
// flag
mFollowingHead = true;
}
}
if (mFollowingHead) {
// calculate time loop for consistency with different framerate
final int loop = deltaTime / Scene.DEFAULT_MSPF;
PointF p1, p2;
float dx, dy;
for (int n = 0; n < loop; n++) {
for (int i = mNumPoints - 1; i > 0; i--) {
p1 = mPoints[i];
p2 = mPoints[i - 1];
dx = p2.x - p1.x;
dy = p2.y - p1.y;
if (mMinLength <= 1 || (dx * dx + dy * dy) > (mSegmentLength * mSegmentLength)) {
// move toward the leading point
p1.x += dx * mMotionEasingX;
p1.y += dy * mMotionEasingY;
}
}
}
// follow the target
if (mTarget != null) {
// set the head
final PointF pos = mTarget.getPosition();
mPoints[0].set(pos.x + mTargetOffset.x, pos.y + mTargetOffset.y);
}
// apply
setPoints(mPoints);
}
}
return super.update(deltaTime);
}
public void setNumPoints(final int numPoints) {
mNumPointsUsed = mNumPoints = numPoints;
if (numPoints < 2) {
mPoints = null;
return;
}
if (mPoints == null || mPoints.length != numPoints) {
mPoints = new PointF[numPoints];
final PointF pos = (mTarget != null) ? mTarget.getPosition() : null;
for (int i = 0; i < numPoints; i++) {
mPoints[i] = new PointF();
if (pos != null) {
mPoints[i].set(pos.x + mTargetOffset.x, pos.y + mTargetOffset.y);
}
}
// find the length
mSegmentLength = mMinLength / (mNumPoints < 2 ? 1 : mNumPoints - 1);
// optimize
mTotalLength = 0;
mFollowingHead = false;
}
// re-count, each point has 2 vertices
allocateVertices(numPoints * 2, VERTEX_POINTER_SIZE);
}
public void setTarget(final Manipulatable target) {
mTarget = target;
if (mTarget != null) {
final PointF pos = mTarget.getPosition();
for (int i = 0; i < mNumPoints; i++) {
mPoints[i].set(pos.x + mTargetOffset.x, pos.y + mTargetOffset.y);
}
// apply
setPoints(mPoints);
}
}