Party-Parrots-At-Sea/src/main/java/seng302/fxObjects/Wake.java

package seng302.fxObjects;

import javafx.scene.CacheHint;
import javafx.scene.Group;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.StrokeLineCap;
import javafx.scene.transform.Rotate;

/**
 * A group containing objects used to represent wakes onscreen. Contains functionality for their animation.
 */
class Wake extends Group {

    //The number of wakes
    private int numWakes = 8;
    //The total possible difference between the first wake and the last. Increasing/Decreasing this will make wakes fan out more/less.
    private final double MAX_DIFF = 75;
    //Increasing/decreasing this will alter the speed that wakes converge when the heading stop changing. Anything over about 1500 may cause oscillation.
    private final int UNIFICATION_SPEED = 750;


    private Arc[] arcs = new Arc[numWakes];
    private double[] rotationalVelocities = new double[numWakes];
    private double[] rotations = new double[numWakes];
    private double baseRad;

    /**
     * Create a wake at the given location.
     *
     * @param startingX x location where the tip of wake arcs will be.
     * @param startingY y location where the tip of wake arcs will be.
     */
    Wake(double startingX, double startingY) {
        super.setLayoutX(startingX);
        super.setLayoutY(startingY);
        Arc arc;
        for (int i = 0; i < numWakes; i++) {
            //Default triangle is -110 deg out of phase with a default wake and has angle of 40 deg.
            arc = new Arc(0, 0, 0, 0, -110, 40);
            arc.setCache(true);
            arc.setCacheHint(CacheHint.SCALE_AND_ROTATE);
            arc.setType(ArcType.OPEN);
            arc.setStroke(new Color(0.18, 0.7, 1.0, 1.0 + (-0.99 / numWakes * i)));
            arc.setStrokeWidth(3.0);
            arc.setStrokeLineCap(StrokeLineCap.ROUND);
            arc.setFill(new Color(0.0, 0.0, 0.0, 0.0));
            baseRad = (20 / numWakes);
            arcs[i] = arc;
        }
        super.getChildren().addAll(arcs);
    }

    /**
     * Sets the rotationalVelocity of each arc.
     *
     * @param rotationalVelocity The rotationalVelocity the wake should move at.
     * @param velocity           The real world velocity of the boat in m/s.
     */
    void setRotationalVelocity(double rotationalVelocity, double velocity) {
        rotationalVelocities[0] = rotationalVelocity;
        for (int i = 1; i < numWakes; i++) {
            double wakeSeparationRad = Math.toRadians(rotations[i - 1] - rotations[i]);
            double shortestDistance = Math.atan2(
                Math.sin(wakeSeparationRad),
                Math.cos(wakeSeparationRad)
            );
            double distDeg = Math.toDegrees(shortestDistance);

            if (rotationalVelocities[i - 1] < 0.01 && rotationalVelocities[i - 1] > -0.01) {
                rotationalVelocities[i] = distDeg / UNIFICATION_SPEED * Math.log(Math.abs(distDeg) + 1) / Math.log(MAX_DIFF / numWakes);

            } else {
                if (distDeg < (MAX_DIFF / numWakes))
                    rotationalVelocities[i] = rotationalVelocities[i - 1] * Math.log(Math.abs(distDeg) + 1) / Math.log(MAX_DIFF / numWakes);
                else
                    rotationalVelocities[i] = rotationalVelocities[i - 1];
            }
        }

        double rad = baseRad + velocity;
        for (Arc arc : arcs) {
            arc.setRadiusX(rad);
            arc.setRadiusY(rad);
            rad += (10 / numWakes) + (velocity / 2);
        }
    }

    /**
     * Arcs rotate based on the distance they would have travelled over the supplied time interval.
     *
     * @param timeInterval the time interval, in microseconds, that the wake should move.
     */
    void updatePosition(long timeInterval) {
        for (int i = 0; i < numWakes; i++) {
            rotations[i] = rotations[i] + rotationalVelocities[i] * timeInterval;
            arcs[i].getTransforms().setAll(new Rotate(rotations[i]));
        }
    }

    /**
     * Rotate all wakes to the given rotation.
     *
     * @param rotation the from north angle in degrees to rotate to.
     */
    void rotate(double rotation) {
        for (int i = 0; i < arcs.length; i++) {
            rotations[i] = rotation;
            rotationalVelocities[i] = 0;
            arcs[i].getTransforms().setAll(new Rotate(rotation));
        }
    }
}