function Shadowmap( light )
{
	//maybe useful
	//this.enabled = true;

	/**
	* Shadowmap resolution, if let to 0 it will use the system default
	* @property resolution
	* @type {Number}
	* @default 0
	*/
	this.resolution = 0;

	/**
	* The offset applied to every depth before comparing it to avoid shadow acne
	* @property bias
	* @type {Number}
	* @default 0.0
	*/
	this.bias = 0;

	/**
	* Which format to use to store the shadowmaps
	* @property format
	* @type {Number}
	* @default GL.DEPTH_COMPONENT
	*/
	this.format = GL.DEPTH_COMPONENT;

	/**
	* Layers mask, this layers define which objects affect the shadow map (cast shadows)
	* @property layers
	* @type {Number}
	* @default true
	*/
	this.layers = 0xFF; //visible layers

	/**
	* If true objects inside the shadowmap will be rendered with the back faces only
	* @property reverse_faces
	* @type {Boolean}
	* @default false
	*/
	this.reverse_faces = true; //improves quality in some cases


	this.shadow_mode = 1; //0:hard, 1:bilinear, ...

	this.linear_filter = true;

	/**
	* The shadowmap texture, could be stored as color or depth depending on the settings
	* @property texture
	* @type {GL.Texture}
	* @default true
	*/
	this._texture = null;
	this._light = light;
	this._fbo = null;
	this._shadow_params = vec4.create(); //1.0 / this._texture.width, this.shadow_bias, this.near, closest_far
	this._shadow_extra_params = vec4.create(); //custom params in case the user wants to tweak the shadowmap with a cusstom shader
}
Shadowmap contains all the info necessary to generate the shadowmap
@class Shadowmap
@constructor
@param {Object} object to configure from