//
//------------------ DOK FILE --------------------------------------------------
+Header	core.2d.gl
=pkg	core.2d.gl
=title	core.2d.gl
=short	a little 2d openGL library
=desc
This little library lets you manage a 2d screen with openGL. You don't need to care about the projections, the matrix, the frustrum or the shaders.
It is based on Sprites of any size.
It works closely with the core.3d.gl library. Before calling 2d functions, you should:
-	call once [[glInitShaders]]
-	create textures with [[textureCreate]]
-	create sprites with [[gl2dSpriteCreate]]
-	define colors with [[colorMakeARGB]]
Then, for each frame:
-	call [[gl2dInitScreen]] to initialize the render buffer
-	call [[gl2dDrawSprite]], [[gl2dDrawColoredSprite]], [[gl2dDrawFlatBox]] to draw your things
-	call [[glSwapBuffers]] to send the render buffer to the screen
//
//
//------------------ PROTO ----------------------------------------------------- gl2dDrawSprite
+Proto	gl2dDrawSprite
=type	fun Sprite Int Int -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function draws a sprite at a given position.
//
+arg	s
=type	Sprite
=desc	A sprite
//
+arg	x
=type	Int
=desc	An integer
//
+arg	y
=type	Int
=desc	An integer
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- gl2dDrawColoredSprite
+Proto	gl2dDrawColoredSprite
=type	fun Sprite Int Int Floats -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function draws a filtered sprite at a given position. The filter is a color multiplication.
//
+arg	s
=type	Sprite
=desc	A sprite
//
+arg	x
=type	Int
=desc	An integer
//
+arg	y
=type	Int
=desc	An integer
//
+arg	color
=type	Floats
=desc	A color vector. See [[colorMakeARGB]]
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- gl2dSpriteUpdateTexture
+Proto	gl2dSpriteUpdateTexture
=type	fun Sprite -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	The sprite's texture is updated. This means that the openGL texture is updated with the content of its attached bitmap. See [[textureUpdate]].
//
+arg	s
=type	Sprite
=desc	A sprite
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- gl2dSpriteUpdateUV
+Proto	gl2dSpriteUpdateUV
=type	fun Sprite Int Int Int Int -> Sprite
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function updates the texture coordinates of the sprite. Texture coordinates derive from a rectangle in the original bitmap coordinates.
//
+arg	src
=type	Sprite
=desc	A sprite
//
+arg	x
=type	Int
=desc	Any integer
//
+arg	y
=type	Int
=desc	Any integer
//
+arg	w
=type	Int
=desc	Any integer
//
+arg	h
=type	Int
=desc	Any integer
//
+arg	result
=type	Sprite
=desc	The sprite src
//
//
//------------------ PROTO ----------------------------------------------------- gl2dSpriteCreate
+Proto	gl2dSpriteCreate
=type	fun Texture -> Sprite
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function creates a [[Sprite]] from an openGL texture. It expects to be followed by a call to [[gl2dSpriteUpdateUV]] to definie the texture coordinates before being rendered with [[gl2dDrawSprite]].
//
+arg	texture
=type	Texture
=desc	A texture. See [[textureCreate]].
//
+arg	result
=type	Sprite
=desc	A new sprite
//
//
//------------------ PROTO ----------------------------------------------------- gl2dDrawFlatBox
+Proto	gl2dDrawFlatBox
=type	fun Int Int Int Int Floats -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function draws a rectangle with a flat color.
//
+arg	x
=type	Int
=desc	Any integer
//
+arg	y
=type	Int
=desc	Any integer
//
+arg	w
=type	Int
=desc	Any positive integer
//
+arg	h
=type	Int
=desc	Any positive integer
//
+arg	color
=type	Floats
=desc	A color vector. See [[colorMakeARGB]]
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- gl2dInitScreen
+Proto	gl2dInitScreen
=type	fun Floats -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc
This function should be called at the begining of a rendering. It initializes the frame and applies a background color.
This allows to use screen coordinates, from 0 to width or from 0 to height (instead of something like [-1, 1]), to draw things during the rendering.
//
+arg	bgColor
=type	Floats
=desc	A color vector. See [[colorMakeARGB]]
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- gl2dDrawBackground
+Proto	gl2dDrawBackground
=type	fun Floats -> Int
=mode	function
=pkg	core.2d.gl
=impl	mcy
=link	
=desc	This function applies a background color.
//
+arg	bgColor
=type	Floats
=desc	A color vector. See [[colorMakeARGB]]
//
+arg	result
=type	Int
=desc	Always 0
//
//
//------------------ PROTO ----------------------------------------------------- Sprite
+Proto	Sprite
=type	Sprite
=mode	structure
=pkg	core.2d.gl
=impl	mcy
=link	
=desc
This is the type for sprites.
A sprite is  defined by:
-	a rectangle (width, height)
-	a [[Texture]], which derives from an original [[Bitmap]]
-	texture coordinates