[Zebestov]

Это я набокопорил с координатами =) вектор vertices неправильно собран.
Вот исправленный код метода drawImage:

function drawImage():void
{
	var a0:Number = angle + diagonalAngle;
	vertices[0] = Math.cos(a0) * diagonalSemiLength + center.x;
	vertices[1] = Math.sin(a0) * diagonalSemiLength + center.y;
 
	var a1:Number = angle + Math.PI - diagonalAngle;
	vertices[2] = Math.cos(a1) * diagonalSemiLength + center.x;
	vertices[3] = Math.sin(a1) * diagonalSemiLength + center.y;
 
	var a2:Number = angle - Math.PI + diagonalAngle;
	vertices[4] = Math.cos(a2) * diagonalSemiLength + center.x;
	vertices[5] = Math.sin(a2) * diagonalSemiLength + center.y;
 
	var a3:Number = angle - diagonalAngle;
	vertices[6] = Math.cos(a3) * diagonalSemiLength + center.x;
	vertices[7] = Math.sin(a3) * diagonalSemiLength + center.y;
 
	canvas.graphics.clear();
	canvas.graphics.beginBitmapFill(image, null, false, true);
	canvas.graphics.drawTriangles(vertices, indices, uvtData);
}