Setting-up the UISlider to change birthrate Note:The slider shouldn’t change the particle system just yet. If ( userInterfaceIdiom] = UIUserInterfaceIdiomPhone) ] Override point for customization after application launch. Now remove the following code from ENHAppDelegate.m. Delete the ENHViewController_iPad.xib file and rename the ENHViewController_iPhone.xib file to ENHViewController.xib. It is easier to use the same view controller on the iPhone and the iPad in this case than it is to edit two separate xib files. The user interface for this application will be very simple. Open Xcode and create a Single View Application.Ĭall it EmissionsTest, use a class Prefix of “ENH”, make it Universal, and Use Automatic Reference Counting.Īdd the QuartzCore Framework to the project. The user will be able to tap on the screen to animate the source of the fire and the slider at the bottom of the screen will control how much fire is emitted. In this tutorial you will create an application that spews fire using a particle system. See CAEmitterCell.h or the CAEmitterCell Class Reference for more details on these properties. This allows the particle system to randomize its properties to create natural-looking particle effects like smoke or fireworks. If you were to set the scale property to 2.0 and the scaleRange property to 1.0, the size of the particles would range from 1.0 to 3.0 times the size of the CGImageRef. For example, the scale property has a corresponding scaleRange property. Many of the properties also include a corresponding range. Those properties include image contents (a CGImageRef), a descriptive name, a scale, spin, lifetime, and others. Rather, it is used to describe the particles themselves. Despite its CA-derived name, it is neither a subclass of CALayer nor a subclass of CAAnimation. The CAEmitterCell class represents the particles themselves. It defines several properties that describe the particle system overall, such as the scale, velocity, birthrate, lifetime, etc. It is the layer that hosts, or emits, the particles of the particle system. The CAEmitterLayer class is a subclass of CALayer. Creating a particle system is easy using CAEmitterLayer and CAEmitterCell. In iOS and OS X there is no need to deal with the complexities of OpenGL to create particle system effects Apple has done the difficult work of creating an efficient implementation in Core Animation. Introducing CAEmitterLayer and CAEmitterCell If many animated copies of a single particle / image can be used to create an effect, you can create the effect using a particle system. You can also simulate a snow globe or confetti or … you-name-it. Apple’s animated “puff of smoke” image sequence – used to remove an application from the OS X dock – could be reimplemented more realistically as a particle system. Delicious Library, for example, famously consumes a book with a fire animation when you remove a book from your virtual bookshelf. They make great touches in productivity apps as well. They are often used to create smoke, explosions, and fire effects in games. Particle systems are fun visual candy to add to your apps.
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