Matrix, rotate and translate help needed

1

I draw() a new bitmap with the use of a transform matrix, but Im having serious problems with calculating de translate positions after rotate…

Is there some kind of formula/function to calculate the matrix.translate Numbers after matrix.rotate ?

What I do now is something like this:


    var matrix = new Matrix();
    matrix.identity();
    matrix.rotate(2 * Math.PI * (rotatie / 360)); //rotatie is a Number that I "post" via a dropbox
    matrix.translate(helpX, helpY); //HELP ME HERE PLEASE :)

    
    var bmd:BitmapData = new BitmapData(b, h);
    bmd.draw(img, matrix);
    
    var bm:Bitmap = new Bitmap(bmd);
    img = bm; //img is a bitmap variable on the stage
    addChild(img);

I actually did read a gazzilion tuts and topics about the matrix, but I didnt find anything about this.
Any help would be appreciated. thx

2 
		public static function PreRotate(img:Object):Array{
			RI = new Array();				
			for (var i:Number = -18; i < 19; i++){ 
				var rotationMatrix:Matrix = new Matrix(); 
				var temp:Number = Math.sqrt((img.width/2)*(img.width/2)+(img.height/2)*(img.height/2)); 
				rotationMatrix.identity()
				rotationMatrix.translate(-img.width/ 2,-img.height / 2); 
				rotationMatrix.rotate(i * Math.PI/180 * 10);				 
				rotationMatrix.translate(temp,temp);				
				RI* = new BitmapData(temp*2, temp*2, true, 0x000000); 					
				RI*.draw(img, rotationMatrix);						
			}
			return RI																	
		}
3

Thank you guys!
The script substance posted is almost perfect, it takes the right sizes and rotation , but it draws the new bitmap on the wrong place, I have to puzzle a little with that.
The new bitmaps need to be on the scene’s x:0 and y:0, while this script moves the new bitmap every time.
I think its beqausse the translate uses the same values for x and y.

once again, THX :slight_smile:

update:
I am a little further now, the code doesnt draw my images on the wrong place anymore, but it does “crop” the “copy” to the smallest value.

For example:
flash loads an image from 400200 px
Rotate it with 90
and draw() a new image, with the right sizes, but the content is now 200200 instead of 200*400.

Im horrible with math, so I hope you guys can help me out once more :slight_smile:

this is what I have so far…


    var rotatie:Number = 90;

    var rotationMatrix:Matrix = new Matrix();
    var tempX:Number = Math.sqrt((img.width/2)*(img.width/2));
    var tempY:Number = Math.sqrt((img.height/2)*(img.height/2));
    
    rotationMatrix.identity();
    rotationMatrix.translate(-img.width/ 2,-img.height / 2);
    rotationMatrix.rotate(2 * Math.PI * (rotatie / 360));
    rotationMatrix.translate(tempX,tempY);

    var bmd:BitmapData = new BitmapData(tempX*2, tempY*2, true, 0x000000);

Since my english isnt that good, here an image what happens

4

Solved, I now have this and works like a charm :slight_smile: (since I only need to rotate with 90)


var rotatie:Number = 90;
    var rotationMatrix:Matrix = new Matrix();
    var tempX:Number = Math.sqrt((img.width/2)*(img.width/2));
    var tempY:Number = Math.sqrt((img.height/2)*(img.height/2));
    var bmd:BitmapData;
    rotationMatrix.identity();
    rotationMatrix.translate(-img.width/ 2,-img.height / 2);
    rotationMatrix.rotate(2 * Math.PI * (rotatie / 360));
    rotationMatrix.translate(tempY,tempX); //this
    
    bmd = new BitmapData(tempY*2, tempX*2, false, 0x00ff00);
    bmd.draw(img, rotationMatrix);