PackedTexture: .h, .cpp
=======================

namespace PackedTextureType
---------------------------

Defines the type of the texture inside a PackedTexture.
Feel free to extend this if you'd like more types.

class PackedTexture
-------------------

The PackedTexture class inherits from :doc:`Texture <texture>` and (along with the OpenGL handle stored by :doc:`Texture <texture>`)
stores a vector describing the layout of images stored one after the other in the texture.
It is mostly used by the SGE GUI system to store images for 3 different button states in one texture.

How to use it?
**************

Along with the texture file, you need to have an XML file in which you need to specify in what order are the images in the texture.
The file has to have a root element named ``textureTypes`` with a children element for each texture (named ``type``).

For example, if you have a file called *myTexture.png* in which the textures are (in order) normal, hover and click textures,
create the file *myTexture.xml*, inside of which is:
::
	<textureTypes>
  	  <type>NORMAL</type>
  	  <type>CLICK</type>
 	  <type>HOVER</type>
	</textureTypes>

Then, simply supply the filename of the texture file to the contructor:
::
	PackedTexture::PackedTexture(fs::path filename);
	
	//eg.
	auto myTexture = sge::PackedTexture("path/to/file");

To access the individual texture coordinates, use:
::
	std::array<glm::vec2, 2> unpackTexture(PackedTextureType::Enum type);

	//eg.
	auto texCoords = myTexture.unpackTexture(PackedTextureType::HOVER);

which will return the texture coordinates (bottom left and upper right) of that specific texture.

.. note:: All of the images inside one texture file need to be of the same size and should preferably be power-of-two.

Details
*******

The function unpackTexture gets the index of the specific texture starting from 0 and the total number of textures
and then calculates the bounds as follows:
::
	bottomLeftBound = { index / totalNumberOfTextures, 0 }
	upperRightBound = { (index + 1) / totalNumberOfTextures, 0 }

.. note:: If no matching texture was found, it will return the coordinates of first texture.