ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with bitmaps
package
{
import flash.display.Sprite;
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.BitmapDataChannel;
}
public class BitmapNoise1 extends Sprite
{
public function BitmapNoise1()
{
var myBitmap:BitmapData = new BitmapData(250, 250,false, 0xff000000);
myBitmap.noise(500, 0, 255, BitmapDataChannel.BLUE,false);
var image:Bitmap = new Bitmap(myBitmap);
addChild(image);
}
}
If you want to create a more organic-looking texture, use the perlinNoise() method. The perlinNoise() method
produces realistic, organic textures that are ideal for smoke, clouds, water, fire, or even explosions.
Because it is generated by an algorithm, the perlinNoise() method uses less memory than bitmap-based textures.
However, it can still have an impact on processor usage, slowing down your content and causing the screen to be
redrawn more slowly than the frame rate, especially on older computers. This is mainly due to the floating-point
calculations that need to occur to process the perlin noise algorithms.
The method accepts nine parameters (the first six are required):
baseX (Number): Determines the x (size) value of patterns created.
baseY (Number): Determines the y (size) value of the patterns created.
numOctaves (uint): Number of octaves or individual noise functions to combine to create this noise. Larger
numbers of octaves create images with greater detail but also require more processing time.
randomSeed (int): The random seed number works exactly the same way as it does in the noise() function. To get
a true random result, use the Math.random() method to pass a random number for this parameter.
stitch (Boolean): If set to true, this method attempts to stitch (or smooth) the transition edges of the image to
create seamless textures for tiling as a bitmap fill.
fractalNoise (Boolean): This parameter relates to the edges of the gradients being generated by the method. If
set to true, the method generates fractal noise that smooths the edges of the effect. If set to false, it generates
turbulence. An image with turbulence has visible discontinuities in the gradient that can make it better approximate
sharper visual effects, like flames and ocean waves.
channelOptions (uint): The channelOptions parameter works exactly the same way as it does in the noise()
method. It specifies to which color channel (of the bitmap) the noise pattern is applied. The number can be a
combination of any of the four color channel ARGB values. The default value is 7.
grayScale (Boolean): The grayScale parameter works exactly the same way as it does in the noise() method. If
set to true, it applies the randomSeed value to the bitmap pixels, effectively washing all color out of the image. The
default value is false.
offsets (Array): An array of points that correspond to x and y offsets for each octave. By manipulating the offset
values, you can smoothly scroll the layers of the image. Each point in the offset array affects a specific octave noise
function. The default value is null.
Last updated 6/6/2012
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