Adding particles

As the icing on the cake, we will include a rain particle effect. To create a particle effect in SceneKit, go to File | New and, under Resource, select SceneKit Particle system. Click Next and, on the next screen, select Rain from the Particle System Template dropdown. Click Next and give the file a name. I called it rain. Now you will have a rain.scnp and spark.png file in the project.

Add the following code at the end of the init function of the GameSCNScene class:

        // add particle system
        let rain = SCNParticleSystem(named: "rain", inDirectory: 
                                                            nil)
        rain!.warmupDuration = 10
        
        let particleEmitterNode = SCNNode()
        particleEmitterNode.position = SCNVector3(0, 100, 0)

        particleEmitterNode.addParticleSystem(rain!)
        self.rootNode.addChildNode(particleEmitterNode)

We create a new constant called rain, assign SCNParticleSystem to it, and provide the...