How to rotate an image

[ChipChamp]

Hey, I'm fairly new to Java, and am attempting to make a game kind of like Asteroids... The problem that I'm having is that I can't figure out how to rotate my ships image... Is there any kind of method to do that, or ... something? :P

(I don't really want to make multiple images of the ship in different rotations)

Thanks!

[ChipChamp]

Okay, so I have figured out how to get the image to rotate, but now I have a problem where sometimes when the player is going around (usually near the sides of the applet) the player kinda... stretches out or something. Here are a couple pictures:
Good:
img181.imageshack.us/img181/9941/pic1bo5.png
Bad:
img364.imageshack.us/img364/3410/pic2dm5.png
(apparently it's not letting me post images or something, so you have to copy the URLs...)

It usually goes away after a second or less... But does anyone know what's causing this? Here is my update method, for double buffering, and my paint method:

public void update (Graphics g)
	{
		if (dbImage == null)
		{
			dbImage = createImage (this.getSize().width, this.getSize().height);
			dbg = dbImage.getGraphics ();
		}

		dbg.setColor (getBackground ());
		dbg.fillRect (0, 0, this.getSize().width, this.getSize().height);

		dbg.setColor (getForeground());
		paint (dbg);

		g.drawImage (dbImage, 0, 0, this);
	}

	public void paint(Graphics g) {
		// clear off screen bitmap
		super.paint(g);
		// cast graphics to graphics 2D
		Graphics2D g2 = (Graphics2D) g;
		AffineTransform tfm = new AffineTransform();
		tfm.rotate(0,0,0);
		g2.setTransform(tfm);
		g2.drawImage(backImage, 0, 0, this);

		tfm.rotate(Math.toRadians(player.angle+90), player.x+32, player.y+32);
		g2.setTransform(tfm);
		g2.drawImage(tank, player.x, player.y, this);		
	}

[hardwired]

does anyone know what's causing this?
I don't have enough to run/test to replicate your report or
offer a fix for your code.
One possible trouble area does stand out:

AffineTransform tfm = new AffineTransform();
// There is no need to do this:
tfm.rotate(0,0,0);
g2.setTransform(tfm);
// unless you are planning to rotate the background image.
// In such a case you do not use the [i]setTransform[/i] method.
// As mentioned in the Method Detail for this method you use
// this only one time to restore the origingal transform after
// you are finished with all transform operations on the
// graphics context (g). However, this may not be necessary in
// AWT drawing since the graphics context [u]may[/u] not be used after
// your are finsihed with it. Restoring the original transform
// with [i]setTransform[/i] is usually necessary in Swing drawing,
// preferably done in the [i]paintComponent[/i] method, in which
// the graphics context is later passed to the [i]paintChildren[/i] and
// [i]paintBorder[/i] methods (see JComponent api Method Detail
// for the [i]paint[/i] method).
// The recommended way to do this then would be:
// Save the original transform for later restoration:
AffineTransform origXform = g2.getTransform();
// apply a rotation transform to the graphics context:
g2.rotate(theta, x, y);
// draw the background image.
g2.drawImage(backImage, 0, 0, this);
// Reverse the last transform:
g2.rotate(-theta, x, y);
// Apply rotation transform to graphics context for player image:
g2.rotate(Math.toRadians(player.angle+90), player.x+32, player.y+32);
//g2.setTransform(tfm);
g2.drawImage(tank, player.x, player.y, this);
// and then after you are done with all transform ops, reset
// the transform to the original (use this method only one time):
g2.setTransform(origXform);
// or you could reverse the rotation transform applied above
// for the player image. You want the transform at the end of
// this method to be the same as it was at the beginning.
// Of course, this may be unnecessary, as mentioned above.
// If so, you could omit the [i]setTransform[/i] calls and use
// the g2.[i]rotate/translate/etc.[/i] – type methods to
// transform/draw/reverse_transform the graphics context as
// shown above.

[alex1287]

The following function will rotate a buffered image that comes in indeterminate if it is a perfect square or not.

    public BufferedImage rotate(BufferedImage image)
    {
      /*
       * Affline transform only works with perfect squares. The following
       *   code is used to take any rectangle image and rotate it correctly.
       *   To do this it chooses a center point that is half the greater
       *   length and tricks the library to think the image is a perfect
       *   square, then it does the rotation and tells the library where
       *   to find the correct top left point. The special cases in each
       *   orientation happen when the extra image that doesn't exist is
       *   either on the left or on top of the image being rotated. In
       *   both cases the point is adjusted by the difference in the
       *   longer side and the shorter side to get the point at the 
       *   correct top left corner of the image. NOTE: the x and y
       *   axes also rotate with the image so where width > height
       *   the adjustments always happen on the y axis and where
       *   the height > width the adjustments happen on the x axis.
       *   
       */
      AffineTransform xform = new AffineTransform();
  
      if (image.getWidth() > image.getHeight())
      {
        xform.setToTranslation(0.5 * image.getWidth(), 0.5 * image.getWidth());
        xform.rotate(_theta);
  
        int diff = image.getWidth() - image.getHeight();
  
        switch (_thetaInDegrees)
        {
        case 90:
          xform.translate(-0.5 * image.getWidth(), -0.5 * image.getWidth() + diff);
          break;
        case 180:
          xform.translate(-0.5 * image.getWidth(), -0.5 * image.getWidth() + diff);
          break;
        default:
          xform.translate(-0.5 * image.getWidth(), -0.5 * image.getWidth());
          break;
        }
      }
      else if (image.getHeight() > image.getWidth())
      {
        xform.setToTranslation(0.5 * image.getHeight(), 0.5 * image.getHeight());
        xform.rotate(_theta);
  
        int diff = image.getHeight() - image.getWidth();
  
        switch (_thetaInDegrees)
        {
        case 180:
          xform.translate(-0.5 * image.getHeight() + diff, -0.5 * image.getHeight());
          break;
        case 270:
          xform.translate(-0.5 * image.getHeight() + diff, -0.5 * image.getHeight());
          break;
        default:
          xform.translate(-0.5 * image.getHeight(), -0.5 * image.getHeight());
          break;
        }
      }
      else
      {
        xform.setToTranslation(0.5 * image.getWidth(), 0.5 * image.getHeight());
        xform.rotate(_theta);
        xform.translate(-0.5 * image.getHeight(), -0.5 * image.getWidth());
      }
  
      AffineTransformOp op = new AffineTransformOp(xform, AffineTransformOp.TYPE_BILINEAR);
  
      return op.filter(image, null);
    }

[DarrylBurke]

Zombie from 2008, closing.

db

THREAD CLOSED