Adobe 12040118 Tutorial - Page 474

an entire snowstorm from a single snowflake layer. You can also use text characters as particles. For example, you can shoot words across the screen, or you can create a sea of text in which a few letters change color, revealing a message. Use Cannon, Grid, Layer Exploder, and Particle Exploder controls to generate particles. Use Layer Map controls to specify a layer in place of each default dot particle. Use Gravity, Repel, and Wall controls to influence overall particle behavior. Use Property Mapper controls to influence particle properties. Use Options to set options, including options for substituting text characters in place of dots. Note: Because of the complexity of Particle Playground, you may experience long computation, preview, and render times. Use Particle Playground 1. Select the layer on which you want particles to exist, or create a new solid layer. 2. Choose Effect > Simulation > Particle Playground. The layer becomes an invisible layer in which only the particles are visible. Animating the layer in the Timeline panel animates the entire layer of particles. 3. Set up a particle generator to determine how particles are created. You can shoot a stream of particles from the Cannon, generate a flat plane full of particles from the Grid, or use the Layer Exploder to create particles from an existing layer. If you've already created particles, you can apply the Particle Exploder to explode them into more new particles. 4. Select your particles. By default, Particle Playground creates dot particles. You can replace the dots with a layer already in the composition or with text characters you specify. 5. Specify the overall behavior of some or all particles. Use Gravity to pull particles in a specified direction, Repel to push particles apart from or toward one another, or Wall to contain or exclude particles from a certain area. 6. Use a layer to specify the behavior of individual particles. You can modify controls that change particle motion, such as speed and force, and controls that change particle appearance, such as color, opacity, and size. The Particle Playground effect renders with anti-aliasing when the layer to which it is applied is set to Best quality. It also applies motion blur to moving particles when both the Motion Blur layer switch and the Enable Motion Blur composition switch are on. When you use a layer as a source for particles, Particle Playground ignores any changes you've made to that layer within that composition, such as changing the Position values. Instead, it uses the layer in its original state. To keep changes for a layer when you use it as a particle source, precompose the layer and use the precomposition layer as the control layer. (See Compound effects and control layers.) Particle content and particle generators Particle Playground can generate three kinds of particles: dots, a layer, or text characters. You can specify only one kind of particle per particle generator. Create particles by using the Cannon, the Grid, the Layer Exploder, and the Particle Exploder. The Grid creates particles in an organized grid format with straight rows and columns. The exploders create particles randomly, like firecracker sparks. The particle generators set the attributes of particles at the moment they are created. After creation, Gravity, Repel, Wall, Exploder, and Property Mapper controls influence particle behavior. For example, if you want particles to stick to grid intersections, you might use the Static Friction option in the Persistent Property Mapper to hold particles in place. Otherwise, as soon as particles are created, they begin moving away from their original grid positions. Cannon controls The Cannon is on by default; to use a different method to create particles, first turn off the Cannon by setting Particles Per Second to zero. The Cannon creates particles in a continuous stream. Position Specifies the (x,y) coordinates from which particles are created. Barrel Radius Sets the size of the barrel radius for the Cannon. Negative values create a circular barrel, and positive values create a square barrel. For a narrow source, such as a ray gun, specify a low value. For a wide source, such as a school of fish, specify a high value. Particles Per Second Specifies how often particles are created. A value of 0 creates no particles. A high value increases the density of the particle stream. If you don't want the Cannon to fire continuously, set keyframes for this control so that the value is 0 at the times when you don't want to create any particles. Direction Sets the angle at which particles are fired. Direction Random Spread Specifies how much each particle's direction deviates randomly from the cannon direction. For example, specifying a 10-degree spread sprays particles in random directions within +/-5° of the cannon direction. For a highly focused stream, such as a ray gun, specify a low value. For a stream that widens quickly, specify a high value. You can specify up to 360°. Velocity Specifies the initial speed of particles in pixels per second as they emanate from the Cannon. Velocity Random Spread Specifies the amount of random velocity of particles. A higher value results in more variation in the velocity of particles. For example, if you set Velocity to 20 and Velocity Random Spread to 10, particles leave the Cannon at velocities ranging from 15 to 25 pixels per second. Color Sets the color of dots or text characters. This control has no effect if you use a layer as the particle source. Particle Radius Sets the radius of dots, in pixels, or the size of text characters in points. This control has no effect if you use a layer as the particle source. Grid controls The Grid creates a continuous plane of particles from a set of grid intersections. The movement of Grid particles is completely determined by the