Tree.java

import java.awt.*;

public class Tree {
    private double fractionLength;
    private int smallestBranch;
    private double branchAngle;
    private int trunkStartX, trunkStartY, trunkEndX, trunkEndY;


    public Tree() {
        fractionLength = .8;
        smallestBranch = 10;
        branchAngle = .2;
        trunkStartX = 400;
        trunkStartY = 700;
        trunkEndX = 400;
        trunkEndY = 600;

    }
    public void drawTree(Graphics g) {
        g.setColor(Color.red);
        /**
         * Draw the trunk of the tree using the Graphic's class
         * drawLine method
         */
        g.drawLine(trunkStartX,trunkStartY,trunkEndX,trunkEndY);

        /**
         * Call the drawBranch method below.  Send in the graphics parameter
         * the length of the trunk, the starting point of the first branch, and the
         * angle 3pi/2.
         */
        drawBranch(g,100,trunkEndX,trunkEndY,(3.0*Math.PI)/2.0);
    }

    public void drawBranch(Graphics g,double currentLength, int startX, int startY, double currentAngle) {
        currentLength = currentLength*fractionLength;

        /**
         * Calculate the angles of both branches
         */
        double angle1 = currentAngle+branchAngle, angle2 = currentAngle-branchAngle;

        /**
         * Calculate the end points of both branches
         */
        int endX1 = (int)(currentLength * Math.cos(angle1) + startX);
        int endY1 = (int) (startY + (currentLength*Math.sin(angle1)));

        int endX2 = (int) (startX +  currentLength*Math.cos(angle2));
        int endY2 = (int) (startY + (currentLength*Math.sin(angle2)));

        /**
         * Draw the branches using Graphics's class drawLine method
         */
        g.drawLine(startX,startY,endX1,endY1);
        g.drawLine(startX,startY,endX2,endY2);

        /**
         * Now check and see if we should recursively call
         * drawBranch.  If so, recursively call drawBranch with
         * appropriate parameters.
         */
        if (currentLength > smallestBranch){
            drawBranch(g,currentLength,endX1,endY1,angle1);
            drawBranch(g,currentLength,endX2,endY2,angle2);
        }
    }


}