Java Reference
In-Depth Information
The code in Listing 2-9 shows how the preceding effect is created.
Listing 2-9.
Particle.fx (Partial)
var cloud = Image{
url: "{__DIR__}cloud.png"
}
public class Particle extends ImageView{
public-init var initialSteps:Integer;//number of steps until removed
public-init var startingOpacity = 1.0;
public-init var speed:Number;//pixels per step
public-init var fadeout = true;
var deltaX;//change in x location per step
var deltaY;//change in y location per step
var stepsRemaining = initialSteps;
init{
image = cloud;
smooth = true;
translateX -= cloud.width/2.0;
translateY -= cloud.height/2.0;
rotate = Math.toDegrees(random.nextFloat()*2.0*Math.PI);
opacity = startingOpacity;
//radom direction in radians
var theta = random.nextFloat()*2.0*Math.PI;
deltaX = Math.cos(theta)*speed;
deltaY = Math.sin(theta)*speed;
}
package function doStep(){
//remove particle if particle has expired
if (--stepsRemaining == 0){
delete this from (parent as Group).content;
}
//advance particle's location
translateX += deltaX;
translateY += deltaY;
if (fadeout){
opacity = startingOpacity*(stepsRemaining as Number)/(initialSteps as Number);
}
rotate += 4;
}
}
The
Particle
class now extends
ImageView
; the image that is displayed is called
cloud
and is a static
variable. In the
init
function the attribute
smooth,
which is defined in the parent class, is set to
true
,
