package {
	
	import flash.display.Sprite;
	import flash.display.BitmapData;
	import flash.display.GraphicsPathCommand;
	 
	public class PerlinWaves extends Sprite {
	
		
		
		public var n:int =32; 	// 	dimensions width
		public var m:int =8;	//	dimensions 'distance'
		public var depthLevel:Number = 360.0; // dimensions: y-level of the bottom floor
		
		// 	two bitmaps: bitmapData (set,get - zdata) holds the info for the height,
		//	textureMap is the texture that is drawn ...
		private var zData:BitmapData; 
		public var textureMap:BitmapData = new BitmapData(1,1,true,0xFFFFFFFF);
		
		private var vertices:Vector.<Number>;
		private	var indices:Vector.<int>;
		private	var uvtData:Vector.<Number>;
		private var i:int;
		private var j:int;
		
		public function PerlinWaves(bmp:BitmapData) {
			
			zData = bmp;
			n = zData.width;
			init();
			
			upDate();
			
		}
		
		public function set bitmapData(bmp:BitmapData):void {
			this.zData=bmp;
			upDate();
		}
		public function get bitmapData():BitmapData {
			return this.zData;
		}
		
		private function init():void {
			
			vertices = new Vector.<Number>();
			indices = new Vector.<int>();
			uvtData = new Vector.<Number>();
			
			
			for (j=0; j!=m; j++) {
				for (i=0 ; i!=n; i++) {
					// x,y coordinates, initialize vector size
					vertices.push(0.0, 0.0);
					
					// texture mapping coordinates between 0,0 and 1,1
					uvtData.push(i/(n-1.0),j/(m-1.0));
				}
			}
			
			//
			// indices for two triangles, CCW
			//
			//		ii-----ii+1
			//		 |\    | 
			//		 | \   |
			//		 |   \ |     
			//		 |    \|       
			//		ii+n---ii+n+1
			
			var ii:int =0;
			for (j=0 ; j!=m-1; j++) {
				for (i=0 ; i!=n-1; i++) {
					indices.push(ii,ii+n+1,ii+1);
					indices.push(ii+n,ii+n+1,ii++);
				}
				ii++;
			}
				
		}
		
		
		private function upDate():void { 
			
			// when the maps updated, the mesh info, e.g uvtData and indices
			// remain the same, only vertices will be updated
			
			var ii:int =0;
			for (j=0; j!=m;j++) {
				for (i=0 ; i!=n; i++) {
					
					// x-coordinate
					vertices[ii++]= i/(n-1); // *100.0; 
					
					if (j==m-1) { // y-coordinate, bottom level
						vertices[ii++]= depthLevel;
					
					} else { // y-coordinate, sampled from image's blue channel
						vertices[ii++]= Number(zData.getPixel(i,j) & 0xFF);
					}
				}
			}
			
			// draw the new graphics
			with (this.graphics) {
				clear();
				beginBitmapFill(this.textureMap);
				drawTriangles(vertices,indices,uvtData);
				endFill();
			}
				
		}
	}
}