Starling Forum

1. 

   c.keimel
   

   Hatchling
   Joined: Jun '12
   Posts: 4

   Hello,

   Let’s assume I have two images in a sprite sheet: A background and a foreground image. The foreground image is the same size as the background, but has a lot of transparent space around it.

   What I would like, is to "trim" the foreground image into the sprite sheet (making it smaller) but to recompute its exact position when it is retrieved from the atlas. After creating the sprite sheet the xml looks like this:

   <TextureAtlas imagePath="sheet.png">
   	<SubTexture name="background" x="2" y="2" width="1024" height="708"/>
   	<SubTexture name="foreground " x="2" y="712" width="764" height="612" frameX="-257" frameY="-96" frameWidth="1024" frameHeight="708"/>
   </TextureAtlas>

   There are two possibilities to work with the data of foreground:

   1. Resize the resulting image to the given frameWidth and frameHeight
   2. Leave the size as it is, but reposition the image to account for frameX and frameY

   
   The first possibility is built into the TextureAtlas. This is nice in a lot of cases. The second approach can be useful as well though: In my case I want to preserve the position of foreground, but would like to make it touchable for user interaction. In this case I would like to keep the foreground image small, so I can distinguish it from other elements.

   I would wish for the TextureAtlas, to be used in both ways. One approach would be to give an extra Parameter to getTexture, or to set the computation mode in the TextureAtlas constructor.

   My workaround at the moment is:

   1. Create two xml files: One with (trim) and one without the frame-Attributes (crop).
   2. Use the xml without the frame-Attributes for the TextureAtlas
   3. After creating an image: Offset the position of the image by frameX and frameY read from the second xml.

   
   Greetings
   Christoph

   Posted 11 months ago #
2. 

   Jeff
   

   Moderating Owl
   Joined: Nov '11
   Posts: 1,287

   If the one feature that you are missing between option 1. or 2. is a smarter hitTest for touch events, maybe another easier option (that wouldn't involve touching the TextureAtlas or Texture classes) would be to just create your own subclass of Starling's Image class that overrides the hitTest function of DisplayObject and use the Image's texture.frame info to make a smaller hit test region? Just an idea off the top of my head, not sure if there would be other complications with this approach.

   Posted 11 months ago #
3. 

   c.keimel
   

   Hatchling
   Joined: Jun '12
   Posts: 4

   I'll try that. Right now I am adding an event listener for touch events to each image.

   Posted 11 months ago #
4. 

   Daniel
   

   Primary Feather
   Joined: Jan '10
   Posts: 2,445

   I haven't tried it out, but it might work like that:

   Texture *textureWithFrame = atlas.getTexture("name");
   Texture *textureWithoutFrame = Texture.fromTexture(textureWithFrame);

   That might be an easy workaround!

   Posted 11 months ago #

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