Althoug I didn't use this technique in any of my games, I'm sharing it hoping that someone wil find it useful. My initial intention was using it in a side-scroller, but other options are possible.
Basically, we want to generate clouds. Not the puffy, realistic ones (which can be made with perlin noise), but more cartoon-like. I got the idea original idea from an Adobe Illustrator tutorial with the same purpose.
Basically, a cartoon cloud is a set of overlapping ellipses that are merged into a single shape:
Fortunately, Java has a very powerful Constructive Geometry set of primitives that act on java.awt.geom.Area objects and allow precisely this kind of operation. The add() method fuses two different shapes into a single one.
The trick to making the cloud is keeping the centers of the ellipses constrained inside a small box at the center of the cloud so that no ellipse strays too far away. Otherwise, we can get wierd effects. The whole code is as simple as:
Random rnd = new Random();
Area cloud = null;
for (int i = 0; i < 10; i++) {
int x = xc+rnd.nextInt(50)-25;
int y = yc+rnd.nextInt(50)-25;
int rx = rnd.nextInt(sizeX-100)+100;
int ry = rnd.nextInt(sizeY-25)+25;
Area newPart = new Area(new Ellipse2D.Double(x,y,rx,ry));
if (cloud == null)
cloud = newPart;
else
cloud.add(newPart);
}
The shadow effect is achieved simply by translating the cloud shape a bit and filling it with a darker color.
g.setColor(Color.darkGray);
g.fill(cloud);
g.translate(-5,-5);
g.setColor(new Color(255,255,255,240));
g.fill(cloud);
Here are some results that you can obtain with this snippet:
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The CloudsTutorial.java application included contains the above code and is a fully-working application.
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CloudsTutorial.java ( 2 Kb ) |