Autodesk 62205-051408-9001 User Guide - Page 380

14 Creating Particle Effects 2. Click Particles to access the Particles controls. For information on reference points, see Changing the Particle Reference Point. For other controls, see Particles Controls. 3. If the particle type uses a multi-frame shape, you can scrub the thumbnail to see all the images. The controls for multi-frame shapes are explained in Random Start Frame, Start At, and Hold. 4. Click Behavior to access the Behavior controls. For information on specific properties, see Behavior Controls. 5. Use the Behavior controls (or the Timeline) to change the basic and variation properties. Note: The over-life properties should only be changed in the Timeline in Graph view. 6. Click Shape to access the Shape controls. For information on shape controls, see Shape Controls. To learn how to use a different shape, see Working with Particle Shapes. 7. To see the shape for the selected particle type, click Current. Changing the Particle Reference Point Each particle shape has a reference point, which is the point to which its behavior transforms (the three sets of Spin and Size behavior properties) are referenced. For example, the reference point is important when the particle is spinning since rotation occurs about the reference point. You can also change the reference point for particles types with Single Particle enabled to make it easier to place the emitter in the scene, or to make it rotate correctly. Each particle has a local axis. If you think of a clock face, the local axis for the particle is the center. The reference point for the particle type is used to position the particle on the clock face. By default, the reference point for a particle type is set at the center of the shape image, so the particle appears at the center of the clock face. As you move the reference point away from the center of the shape image, the particle (on the clock face) moves away from the local axis (the center of the clock). In other words, the reference point stays at the center of the clock-when the particle spins, it will spin around the clock. The tip of the clock hand is where the particle is. You change the reference point to define the distance and angle. To continue with the clock analogy, the length of the hand is the distance, and the angle from the center of the shape image to the reference point controls the orientation of the shape at the end of the clock hand. The particles for a particle type emit from emission points. For a point emitter, there is only one such point; for line, circle, and area emitters, there can be any number of such points. In the following example, the line emitter has two emission points. The reference point for a particle type is set to the right. Two emission points show the resulting spin. 364