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Thread: Drawing a Star of David

  1. #1
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    Default Drawing a Star of David

    Hello!

    I am trying to draw a Star of David using drawLine.

    The assignment calls for the creation of four quadrants, with each quadrant containing a specified shape. In the lower right quadrant, I need to create the star.

    Now I know that the star consists of two triangles - one pointed upwards and the other downwards. I have created triangles pointed in opposite directions, but when I view them, it definitely does NOT look like the star.

    Can anybody try to help me figure out this likely simple mistake?
    import javax.swing .*;
    import java .awt .*;
    import java .applet.*;
     
    public class JApplet extends Applet
    {
    public void paint(Graphics Sketch)
    {
    int Row,Col,k,Side,Height ;
    int PointAx,PointBx,PointCx,PointDx,PointEx,PointFx,Po intGx ;
    int PointAy,PointBy,PointCy,PointDy,PointEy,PointFy,Po intGy ;
    int CenterAx,CenterAy,CenterBx,CenterBy,CenterCx,Cente rCy,CenterDx,CenterDy,Offset;
     
    Dimension RowCol;
     
    RowCol = getSize() ;
    Row = RowCol.width - 1 ;
    Col = RowCol.height - 1;
     
    Sketch.setColor(Color.red );
    Sketch.drawLine(0, 0,Row, 0);
    Sketch.drawLine(0,Col,Row,Col);
    Sketch.drawLine(0, 0, 0,Col);
    Sketch.drawLine(Row,0,Row,Col);
     
    Sketch.setColor(Color.blue );
    Sketch.drawLine(Row/2, 0,Row/2,Col );
    Sketch.drawLine(0 ,Col/2,Row ,Col/2);
     
    Offset = Col/16 ;
    CenterAx = Row/4 ;
    CenterAy = Col/4 ;
    CenterBx = 3*Row/4;
    CenterBy = Col/4 ;
    CenterCx = Row/4 ;
    CenterCy = 3*Col/4;
    CenterDx = 3*Row/4;
    CenterDy = 3*Col/4;
     
    // STAR OF DAVID
     
    Height = (Col - 2 * Offset) / 2 ;
    Side = (int) (2 * Math.sqrt(3) * Height / 3);
     
    PointAx = CenterDx ;
    PointAy = Col /2 + Offset / 2 ;
    PointBx = CenterDx + Side / 2 ;
    PointBy = Col - Offset /2 ;
    PointCx = CenterDx - Side / 2 ;
    PointCy = PointBy ;
    PointDx = CenterDx + Side / 2 ;
    PointDy = Col / 2 + Offset / 2;
    PointEx = PointAx ;
    PointEy = Col - Offset / 2 ;
    PointFx = CenterDx - Side / 2 ;
    PointFy = PointDy ;
     
    Sketch.setColor(Color.orange);
    Sketch.drawLine(PointAx,PointAy,PointBx,PointBy);
    Sketch.drawLine(PointBx,PointBy,PointCx,PointCy);
    Sketch.drawLine(PointCx,PointCy,PointAx,PointAy);
    Sketch.drawLine(PointDx,PointDy,PointEx,PointEy);
    Sketch.drawLine(PointEx,PointEy,PointFx,PointFy);
    Sketch.drawLine(PointFx,PointFy,PointDx,PointDy);
     
     
    }
    }
    Last edited by copeg; July 31st, 2012 at 07:00 PM.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Drawing a Star of David

    Try taking a piece of paper, draw the shape on it, number the lines that are needed to draw the shape, label each line end with its x,y values and then for each line, record the x,y values for ends of the line.
    There should be 6 line with each line having two pairs of x,y values (one for each end)
    Then code the drawLine() method calls for those 6 lines using the x,y values.

    BTW JApplet is the name of a Java SE class.

    Also posted at:
    http://forums.devshed.com/java-help-...ml#post2808400
    Last edited by Norm; July 31st, 2012 at 03:14 PM. Reason: added link
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Administrator copeg's Avatar
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    Default Re: Drawing a Star of David

    @tryingtolearn, don't delete your threads. I have reverted your post.

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