/* Block Dissolve Experiments
	
	Scripting Basics: pulling random values from within a defined range
	A common scripting requirement is to pull random values from within a defined range. For example, in the block dissolve transition the individual blocks of video are extracted from the video in a random order.  As an example, let's revisit our float away video wall script (http://www.creative-workflow-hacks.com/2006/07/09/how-to-make-a-float-away-video-wall-in-after-effects-via-scripting/)  and customize it to work in the same manner as a block dissolve but with a little more flair. We will scale the individual blocks up instead of just transitioning on and off.

	
	Copyright 2006 - Dale Bradshaw, dale@creative-workflow-hacks.com http://creative-workflow-hacks.com
	
	Free To Distribute, but you must maintain this header if used without alteration, please also include a link to http://creative-workflow-hacks.com if posted on the web
	If you use parts of this script please include my contact info as attribution (suggested but not required...thanks)
	
	v1.0 July 8, 2006

	
*/
   function main(){
      
    
     //calculate units
   	 var footageWidth = selectedItemInfo.width;
   	 var gridWidth = win.videoGridWidth.value;
     var widthUnit = footageWidth / gridWidth;
     var footageHeight = selectedItemInfo.height;
   	 var gridHeight = win.videoGridHeight.value;
     var heightUnit = footageHeight / gridHeight;
     var speedBase = win.speed.value;
     
     app.beginUndoGroup("Apply Block Dissolve Grid");
     
     var gridArray = new Array();
     var counter = 0;
     
     for(x = 0; x < gridWidth; x++){
     	for(y= 0; y < gridHeight; y++){
         	gridArray.push(++counter);   	
     	}
     }
    
    
     
	for(x = 0; x < gridWidth; x++){
     	for(y= 0; y < gridHeight; y++){
     		var itemToMask = selectedItemInfo.source.duplicate();
     		
     		newMask = itemToMask.Masks.addProperty("Mask");
			newMask.inverted = false;
			myMaskShape = newMask.property("maskShape");
			myShape = myMaskShape.value;
			myShape.closed = true;
		
			var tempVertices = new Array();
			
			tempVertices.push([x * widthUnit , y * heightUnit]);
			tempVertices.push([x * widthUnit + widthUnit , y * heightUnit]);
			tempVertices.push([x * widthUnit + widthUnit , y * heightUnit + heightUnit]);
			tempVertices.push([x * widthUnit , y * heightUnit + heightUnit]);
			myShape.vertices = tempVertices;
			myMaskShape.setValue(myShape);
		
			scaleProp = itemToMask.scale;
			scaleProp.setValueAtTime(0, [0,0]);
			
				
			var random = Math.floor(Math.random() * gridArray.length);
			var startTime = gridArray.splice(random, 1) * (win.speed.value * .10);
			var endTime  = startTime + (win.speed.value * .10);
			scaleProp.setValueAtTime(startTime, [0,0]);
			scaleProp.setValueAtTime(endTime, [100,100]);
		
			
			/* alternate styles
			scaleProp = itemToMask.scale;
			scaleProp.setValueAtTime(0, [0,0]);
			var random = Math.random(gridArray.length);
			var startTime = gridArray.pop(random) * .2;
			var endTime  = startTime + .2;
			scaleProp.setValueAtTime(startTime, [0,0]);
			scaleProp.setValueAtTime(endTime, [100,100]);
			
			
			var startTime = (x + y) * (win.speed.value * .10);
			var endTime = startTime + (win.speed.value * .10);
			scaleProp.setValueAtTime(startTime, [0,0]);
			scaleProp.setValueAtTime(endTime, [100,100]);
     		*/
     		
     		//thanks to Jeff @ http://www.redefinery.com for the ALPHA_ADD
			itemToMask.blendingMode = BlendingMode.ALPHA_ADD;
     	}
     }
     
     selectedItemInfo.source.enabled = false;
     app.endUndoGroup();	
     
   }
	

  	//UI setup
  
  	//help text
  	
  	function usage(){
	
		var usage = "Use this script to apply a masked grid to a video or still source, the script applies a Block Dissolve effect.";
		alert(usage);
	}
	
	
	
    //UI build
  	function buildUI(){
		
	 if (win != null) {
		 win.GridPnl = win.add('panel', [20,25,230,145], 'Video Grid Size:');
		 
		 win.videoGridWidthText = win.GridPnl.add('statictext', [15,20,105,30], 'Width:');
		 win.videoGridWidthValuesText = win.GridPnl.add('statictext', [15,35,205,45], '2                                                       10');
		
		 win.videoGridWidth = win.GridPnl.add ("slider",[10,48,205,58], 5, 2, 10);
		 win.videoGridWidth.value = 5;
		
		 win.videoGridHeightText = win.GridPnl.add('statictext', [15,70,105,80], 'Height:');
		 
		 win.videoGridHeightValuesText = win.GridPnl.add('statictext', [15,85,205,95], '2                                                       10');
		 win.videoGridHeight = win.GridPnl.add ("slider",[10,98,205,108], 5, 2, 10);
		 win.videoGridHeight.value = 5;
		
		 win.SpeedPnl = win.add('panel', [20,150,230,195], 'Speed:');
		 win.speed = win.SpeedPnl.add ("slider",[10,25,205,35], 2, 1, 100);
		 win.speed.value = 2;
		
		 win.helpBtn = win.add('button', [20,205,50,225], '?', {name:'help'});
     	 win.helpBtn.onClick = usage;
     	 win.cancBtn = win.add('button', [105,205,165,225], 'Cancel', {name:'cancel'});
     	 win.cancBtn.onClick = function () {this.parent.close(0)};
     	 win.okBtn = win.add('button', [172,205,230,225], 'OK', {name:'ok'});
      	 win.okBtn.onClick = function () {main();};
      	
		 
      }
         return win

	}
  
  //check that a single FootageItem is selected
   
   function checkPrerequisites(){
		
		var selectedCount = 0;
		
		var selectAlert = "Please select a single Footage Item in a Comp.";
		if ((activeItem != null) && (activeItem instanceof CompItem)){
			var selectedLayers = activeItem.selectedLayers; 
		}else{
			var selectedLayers = '';
		}
 
		var matchingLayers = new Array();               
		var layer;
		
		
		for (var i = 0; i < selectedLayers.length; i++)
		{
    		layer = selectedLayers[i];
 
    		if (layer.source instanceof FootageItem){
        		matchingLayers[matchingLayers.length] = layer;
			}
		}

			
			if(matchingLayers.length > 1 || matchingLayers.length == 0){
				
				selectedItemInfo.source = '';
				selectedItemInfo.width = '';
				selectedItemInfo.height = '';

				alert(selectAlert);	
			}else{
				
				selectedItemInfo.source = matchingLayers[0];
				selectedItemInfo.width = matchingLayers[0].width;
				selectedItemInfo.height = matchingLayers[0].height;
				 
				if(w != null){
					w.show();
				}else{
					alert("Couldn't build UI");
				}
				
			}
		
}
	
//globals
	var items = app.project.items;
	var activeItem = app.project.activeItem;
	var selectedItemInfo = {source:"", width:"", height:""};
	var win = new Window('palette', 'Create Float Away Video Wall',[100,100,350,345]);
	var w = buildUI(); 
	checkPrerequisites();