//AS3///////////////////////////////////////////////////////////////////////////
// 
// Copyright 2009 ImpTech.
//
// http://pv3d.org/2009/06/13/how-to-click-on-stuff-in-papervision3d-viewport-viewportlayers-interactivescene3devent-mouse3d-and-moviematerial-buttons/
// aka http://tinyurl.com/ylyz23a
// 
////////////////////////////////////////////////////////////////////////////////

package
{
	public class Papervision3D_Notes
	{
		public function Papervision3D_Notes()
		{
			super();
		}
		
		public function almostOrthogonicView():void
		{
			// Update all transformations //
			displayObject3D.updateTransform();
			
			// Set camera trasform to match object transform //
			camera.copyTransform( displayObject3D.transform );
			
			// Backup camera away from object //
			camera.moveBackward( ( ( camera.zoom - 1 ) * camera.focus ) - Math.abs( camera.z ) );
		}
		
		public function getObj2DCords ( o:DisplayObject3D, camera:CameraObject3D,  offsetX:Number = 0, offsetY:Number = 0 ):Point
		{
			var view:Matrix3D = o.view;
			var persp:Number = (camera.focus * camera.zoom) / (camera.focus + view.n34);
			return new Point ( (view.n14 * persp) + offsetX, (view.n24 * persp) + offsetY );
		}
		
		public function getDimentions():void
		{
			dO3D.calculateScreenCoords( camera );
			var screenCoords:String		= int( dO3D.screen.x ) + 'x' + int( dO3D.screen.y ) + 'x' + int( dO3D.screen.z );
			var perspective:Number		= camera.focus * camera.zoom / dO3D.screen.z;
			
			var obj:Object				= new Object();
			obj.size					= 100; // Can this be pulled from the DirectObject3D or must it be saved in extra?
			obj.scene					= new Object();
			obj.scene.width				= dO3D.scaleX * obj.size;
			obj.scene.height			= dO3D.scaleY * obj.size;
			obj.screen					= new Object();
			obj.screen.width			= dO3D.scaleX * obj.size * perspective;
			obj.screen.height			= dO3D.scaleY * obj.size * perspective;
		}
		
		// Calculating Perspective //
		public function getPerspective():void
		{
			var perspective:Number	= camera3D.focus * camera3D.zoom / screen.z;
			var x:Number			= object.x * perspective;
			var y:Number			= object.y * perspective;
			
			perspective = camera3D.focus * camera3D.zoom / camera3D.focus; // Old?
		}
		
		// Converting 3D X and Y coordinates to Screen X & Y coordinates //
		public function getScreenXY():void
		{
			displayObject3D.calculateScreenCoords( camera3D ); // Must be called each time you wish to update the DisplayObject3D.screen property.
			sprite.x	= displayObject3D.screen.x + ( viewport3D.width / 2 );
			sprite.y	= displayObject3D.screen.y + ( viewport3D.height / 2 ); // might be minus half of viewport3D.height.
		}
		
		// Positioning: Equations -- http://blog.computerelibol.com/?p=3 //
		public function positioningEquations():void
		{
			//compute the distance
			var distance:Number = cam.focus*cam.zoom-cam.focus;

			//Compute the perspective
			var persp:Number = cam.focus*cam.zoom/distance;

			//Compute half of the width of the item at the computed distance,
			//we need this value because the registration point of 3D display objects are at their center,
			//and we don't want objects falling outside of xArea
			var perspItemWidth:Number = item.width/2*persp;

			//The following operation gives us a value which will produce the inverse ratio of persp
			var negatePersp:Number = 1/persp;

			//First subtract item.width,
			//which we've computed perspective for at item.screen.z from xArea,
			//then apply the inverse operation of perspective on xArea,
			//we should think of xArea as if it were the screen.x of an object at item.sceen.z
			var negatedXArea:Number = (xArea-perspItemWidth)*negatedPersp;
		}
		
		// Scaling: Equations -- http://blog.computerelibol.com/?p=3 //
		public function scalingEquations():void
		{
			//Solve for perfect distance
			var distance:Number = cam.focus*cam.zoom-cam.focus;

			//or just get it
			distance = Math.abs(item.z-cam.z);

			//Solve for cam.zoom
			cam.zoom = (cam.focus + distance) / cam.focus;

			//Solve for cam.focus
			cam.focus = distance / (cam.zoom * (1-1/cam.zoom));


			//negate perspective from screenX/screenY
			//this equation has been changed since 10/09/2008 to exclude the addition of cam.focus to distance before the division
			var negatePersp:Number = 1/(cam.focus*cam.zoom/distance);
		}
	}
}