Passing Texture Atlas into FlxBackdrop instead of single image for optimization

[Shaun Michael K. Stone]

Hi all,

So I have a foreground layer and a few background layers. I have packed this all into Sparrow data using Texturepacker as I want to contain everything in one spritesheet. The limitation of FlxBackdrop is that you pass the string of the image you want to repeat over and over:

function new(Graphic:Dynamic, ?ScrollX:Float = 1, ?ScrollY:Float = 1, ?RepeatX:Bool = true, ?RepeatY:Bool = true):Void

HillsOne = new FlxBackdrop("assets/single/HillsOne.png", 1, 0, true, false);        
add(HillsOne);

I want to pass in the spritesheet rather than the single image, as I do with the game objects:

var textureAtlas:SparrowData = new SparrowData(
    "assets/sheets/Desktop.xml",
    "assets/sheets/Desktop.png"
);

this.loadGraphicFromTexture(textureAtlas, false, 'HillsOne');

How can I do this?

[Sam Bellman]

I thinks this should work:

var frame:TextureAtlasFrame = null;

for (i in 0...textureAtlas.frames.length)

{

if (textureAtlas.frames[i].name == "bg")

{

frame = textureAtlas.frames[i];

break;

}

}

var textureRegion:TextureRegion = new TextureRegion(FlxG.bitmap.add(texture.asset), Math.floor(frame.frame.left), Math.floor(frame.frame.top), Math.floor(frame.frame.width), Math.floor(frame.frame.height), 0, 0, Math.floor(frame.frame.width), Math.floor(frame.frame.height));

var backdrop:FlxBackdrop = new FlxBackdrop(textureRegion, 1, 1, true, true);

There might be a better, cleaner way of doing it but this is how I did it in a project I had. I was using TexturePackerXMLData but I don't think it should make a difference - you're just creating a Texture region with the asset from the texturepacker and feeding it the frame data then using that in the FlxBackdrop.

[Shaun Michael K. Stone]

FlxG.bitmap.add(texture.asset)

Where do you get the texture.asset from?

[Sam Bellman]

I think I meant textureAtlas.asset, textureAtlas being a TexturePackerXMLData , so it should be the same as your sparrowData. I didn't copy and paste from my stuff, I was writing on the fly but if that doesn't work I can check up exactly what I did when I get back home.

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[Shaun Michael K. Stone]

Okay, thanks for helping, Sam. This is what I got:

package helpers;

import flixel.addons.display.FlxBackdrop;

import flixel.FlxG;

import flixel.util.loaders.SparrowData;

import flixel.util.loaders.TextureAtlasFrame;

import flixel.util.loaders.TexturePackerXMLData;

import flixel.util.loaders.TextureRegion;

/**

 * @author Shaun Stone (SMKS)

 */

class AtlasImageExtractor

{

public function new() {}

/**

* 

* @param name

* @param textureAtlas

* @return

*/

public static function getImageByName(name:String, textureAtlas:SparrowData):TextureRegion 

{

var frame:TextureAtlasFrame = null;

for (i in 0...textureAtlas.frames.length)

{

if (textureAtlas.frames[i].name == name)

{

frame = textureAtlas.frames[i];

break;

}

}

if (frame == null) {

throw "Frame not found in atlas";

}

return buildTextureRegion(frame);

}

/**

* 

* @param frame

* @return

*/

private static function buildTextureRegion(frame:TextureAtlasFrame):TextureRegion 

{

var texture = new TexturePackerXMLData(

PathAssets.getAtlasXml(),

                        PathAssets.getAtlasAsset()

);

var textureRegion:TextureRegion = new TextureRegion(

FlxG.bitmap.add(texture.asset), 

Math.floor(frame.frame.left), 

Math.floor(frame.frame.top), 

Math.floor(frame.frame.width), 

Math.floor(frame.frame.height), 

0, 

0, 

Math.floor(frame.frame.width), 

Math.floor(frame.frame.height)

);

return textureRegion;

}

}

[Sam Bellman]

That looks good - you should be able to pass in textureAtlas:SparrowData to buildTextureRegion and use that instead of creating a new TexturePackerXMLData. They both extend TexturePackerData so your sparrow data will have the asset property which you can use.

[Shaun Michael K. Stone]

Ahh of course. Here is the final:

package helpers;

import flixel.addons.display.FlxBackdrop;

import flixel.FlxG;

import flixel.util.loaders.SparrowData;

import flixel.util.loaders.TextureAtlasFrame;

import flixel.util.loaders.TexturePackerXMLData;

import flixel.util.loaders.TextureRegion;

/**

 * This is used to do the FlxBackdrop using an atlas instead

 * of a single image

 * 

 * @author Shaun Stone (SMKS)

 */

class AtlasImageExtractor

{

public function new() {}

/**

* 

* @param name

* @param textureAtlas

* @return

*/

public static function getImageByName(name:String, textureAtlas:SparrowData):TextureRegion 

{

var frame:TextureAtlasFrame = null;

for (i in 0...textureAtlas.frames.length)

{

if (textureAtlas.frames[i].name == name)

{

frame = textureAtlas.frames[i];

break;

}

}

if (frame == null) {

throw "Frame not found in atlas";

}

return buildTextureRegion(frame, textureAtlas);

}

/**

* 

* @param frame

* @return

*/

private static function buildTextureRegion(frame:TextureAtlasFrame, textureAtlas:SparrowData):TextureRegion 

{

var textureRegion:TextureRegion = new TextureRegion(

FlxG.bitmap.add(textureAtlas.asset),