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Thread: Writing a method to draw a rotatable rectangle using Graphics2D

  1. #1
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    Default Writing a method to draw a rotatable rectangle using Graphics2D

    I am trying to create a method (for robocode) that draws a rotatable rectangle with the (X,Y) coordinates referring to the center of rotation. I have created a method stub, but cannot figure out the actual math for the problem.

    //draws a rectangle centered on (x, y) with h heading in degrees, 0 is up, 90 is right. Sides are of length l and of height w
    public static void drawRotatedRect(Graphics2D g, double x, double y, double h, double l, double w, Color c)
    {
         Color returnColor = g.getColor();
         g.setColor(c);
     
         //draw four sides using Graphics.drawLine()?
     
         g.setColor(returnColor);
    }

    What mathy shenanigans can I use to calculate the XY's of the four corners, so I can pass them into Graphics.drawLine()? Thanks in advance


  2. #2
    Administrator copeg's Avatar
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    Default Re: Writing a method to draw a rotatable rectangle using Graphics2D

    Unless you are required to write the math yourself, an easier way would be to use the methods available in the Graphics2D or AffineTransform class - namely rotate and translate (its always a good idea to get the AffineTransform prior to setting these methods, and reset it afterwards to avoid affecting the transform of future drawing)

  3. The Following User Says Thank You to copeg For This Useful Post:

    johnpooley3 (May 17th, 2012)

  4. #3
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    Default Re: Writing a method to draw a rotatable rectangle using Graphics2D

    Is this the correct way to implement that class?

    public static void drawRotatedRect(Graphics2D g, double x, double y, double heading, double h, double w)
    	{
    	     AffineTransform returnTransform = g.getTransform();
    	     g.setTransform(AffineTransform.getRotateInstance(heading, x, y));
    	     g.drawRect((int) (x-w/2), (int) (y-h/2), (int) w, (int) h);
    	     g.setTransform(returnTransform);
    	}

    Because when I run this method (using robocode) it gives me this stack trace and draws a rectangle without rotation:

    java.lang.ArrayIndexOutOfBoundsException: 63
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.readMethod(Graphics2DSerialized.java:2172)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1418)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    java.lang.ArrayIndexOutOfBoundsException: -16
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.readMethod(Graphics2DSerialized.java:2172)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1418)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    java.lang.ArrayIndexOutOfBoundsException: -67
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.readMethod(Graphics2DSerialized.java:2172)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1418)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    java.nio.BufferUnderflowException
    	at java.nio.Buffer.nextGetIndex(Buffer.java:478)
    	at java.nio.HeapByteBuffer.getInt(HeapByteBuffer.java:336)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTranslate_int(Graphics2DSerialized.java:1619)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1422)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    java.nio.BufferUnderflowException
    	at java.nio.Buffer.nextGetIndex(Buffer.java:478)
    	at java.nio.HeapByteBuffer.getInt(HeapByteBuffer.java:336)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTranslate_int(Graphics2DSerialized.java:1619)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1422)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    java.lang.ArrayIndexOutOfBoundsException: -36
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.readMethod(Graphics2DSerialized.java:2172)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processQueuedCall(Graphics2DSerialized.java:1418)
    	at net.sf.robocode.robotpaint.Graphics2DSerialized.processTo(Graphics2DSerialized.java:1393)
    	at net.sf.robocode.ui.battleview.BattleView.drawRobotPaint(BattleView.java:511)
    	at net.sf.robocode.ui.battleview.BattleView.drawBattle(BattleView.java:325)
    	at net.sf.robocode.ui.battleview.BattleView.update(BattleView.java:180)
    	at net.sf.robocode.ui.battleview.BattleView.access$500(BattleView.java:55)
    	at net.sf.robocode.ui.battleview.BattleView$BattleObserver.onTurnEnded(BattleView.java:683)
    	at net.sf.robocode.battle.events.BattleEventDispatcher.onTurnEnded(BattleEventDispatcher.java:131)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.awtOnTurnEnded(AwtBattleAdaptor.java:128)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor.access$200(AwtBattleAdaptor.java:35)
    	at net.sf.robocode.ui.battle.AwtBattleAdaptor$BattleObserver$2.run(AwtBattleAdaptor.java:208)
    	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
    	at java.awt.EventQueue.access$000(EventQueue.java:85)
    	at java.awt.EventQueue$1.run(EventQueue.java:643)
    	at java.awt.EventQueue$1.run(EventQueue.java:641)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

    Thanks again!

  5. #4
    Administrator copeg's Avatar
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    Default Re: Writing a method to draw a rotatable rectangle using Graphics2D

    The stack trace has nothing to do with the drawRotatedRect method you posted. See your drawRobotPaint...line 511 in the BattleView class to be exact

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