Using the Super Spray Particle System

The icon size can be set or the icon can be hidden in the viewport. You can also set the particles to be displayed in the viewport as Dots, Ticks, Meshes, or Bounding Boxes. The Percentage value is the number of the total particles that are visible in the viewport and should be kept low to ensure rapid viewport updates.

Particle Generation rollout

The Particle Generation rollout, shown in Figure 35.6, is where you set the number of particles to include in a system as either a Rate or Total value. The Rate value is the number of particles per frame that are generated. The Total value is the number of particles generated over the total number of frames. Use the Rate value if you want the animation to have a steady stream of particles throughout the animation; use the Total value if you want to set the total number of particles that will appear throughout the entire range of frames .

Figure 35.6: The Particle Generation rollout lets you control the particle motion.

In the Particle Motion group , the Speed value determines the initial speed and direction of particles. The Variation value alters this initial speed as a percentage of the Speed value. A high Variation value results in particles with all sorts of different speeds.

In the Particle Timing group, you can set when the emitting process starts and stops. Using the Display Until value, you can also cause the particles to continue displaying after the emitting has stopped . The Life value is how long particles stay around, which can vary based on another Variation setting.

When an emitter is animated (such as moving back and forth), the particles can clump together where the system changes direction. This clumping effect is called puffing . The Subframe Sampling options help reduce this effect. The three options are Creation Time (which controls emitting particles over time), Emitter Translation (which controls emitting particles as the emitter is moved), and Emitter Rotation (which controls emitting particles as the emitter is rotated . All three options can be enabled, but each one that is enabled adds the computation time required to the render.

You can specify the particle size along with a Variation value. You can also cause the particles to grow and fade for a certain number of frames.

The Seed value helps determine the randomness of the particles. Clicking the New button automatically generates a new Seed value.

Particle Type rollout

The Particle Type rollout, shown in Figure 35.7, lets you define the look of the particles. At the top of the rollout are three Particle Type options: Standard Particles, MetaParticles, and Instanced Geometry.

Figure 35.7: The Particle Type rollout (shown in four parts ) lets you define how the particles look.

If you select Standard Particles as the particle type, you can select which geometric shape you want to use from the Standard Particles section. The options are Triangle, Special, Constant, Six Point, Cube, Facing, Tetra, and Sphere.

The Special type consists of three intersecting planes, which are useful if you apply maps to them. The Facing type is also useful with maps; it creates a simple, square face that always faces the viewer. The Constant type maintains the same pixel size, regardless of the distance from the camera or viewer. The Six Point option renders each particle as a 2D six-pointed star. All other types are common geometric objects.

Tutorial: Creating a fireworks fountain

For an example of the Super Spray particle system, you create a fireworks fountain. Fireworks are essentially just lots of particles with a short life span and a high amount of self- illumination . (Tell yourself that the next time you watch a fireworks display.)

To create a fireworks fountain using a particle system, follow these steps:

1. Open the  Fireworks fountain.max file from the Chap 35 directory on the DVD.

   This file includes a simple fountain base and the Gravity space warp to cause the particles to curve back toward the ground.

   Tip

   Some of the most amazing special effects are made possible by combining particle systems with Space Warps.

2. Select the Create Particles Super Spray menu command, drag in the Top view, and position the system at the top of the cylinder with the direction arrow pointing toward the sky.

3. Open the Modify panel, and set the Off Axis Spread to 45 and the Off Plane Spread to 90 . In the Particle Generation rollout, set the Total of particles to 2000 with a Speed of 20 and a Variation of 100 . Set the Emit Start to and the Emit Stop to 100 . Set the Display Until to 100 and the Life to 25 with a Variation of 20 . The Size of the particles should be 5 .

4. Open the Material Editor (by pressing the M key), and select the first sample slot. This slot includes a material named Spark. Drag the material from the Material Editor to the particle system's icon.

5. Select the Super Spray icon, right-click it to open the pop-up menu, and select the Properties menu option. In the Object Properties dialog box, select the Object Motion Blur option.

Figure 35.8 shows sparks emitting from the fireworks fountain.

Figure 35.8: The Super Spray particle system is used to create fireworks sparks.

Tutorial: Adding spray to a spray can

The Super Spray particle system is complex enough to warrant another example. What good is a spray can without any spray? In this tutorial, we create a spray can model and then use the Super Spray particle system to create the spray coming from it.

To create a stream of spray for a spray can, follow these steps:

1. Open the  Spray can.max file from the Chap 35 directory on the DVD.

   This file includes a simple spray can object created using a cylinder for the can base and the nozzle and a lathed spline for the top of the can.

2. Select the Particle Systems subcategory button from the drop-down list, and click the Super Spray button. Drag in the Top viewport to create the Super Spray icon, and position it at the mouth of the nozzle.

3. In the Basic Parameters rollout, set the Off Axis Spread to 20 and the Off Plane Spread to 90 . In the Particle Generation rollout, set the Emit Rate to 1000 , the Speed to 20 , and the Life to 30 . Set the Size of the particles to 5 .

4. Open the Material Editor (by pressing M), and select the material named Spray Mist. Then drag this material onto the Super Spray icon to apply this material to the Super Spray particle system.

Figure 35.9 shows the fine spray from an aerosol can.

Figure 35.9: Using a mostly transparent material, you can create a fine mist spray.

Using the MetaParticles option

The MetaParticles option in the Particle Type rollout makes the particle system release Metaball objects. Metaballs are viscous spheres that, like mercury , flow into each other when close. These particles take a little longer to render but are effective for simulating water and liquids. The MetaParticles type is available for the Super Spray, Blizzard, PArray, and PCloud particle systems.

Selecting the MetaParticles option in the Particle Types section enables the MetaParticle Parameters group. In this group are options for controlling how the MetaParticles behave. The Tension value determines how easily objects blend together. MetaParticles with a high-tension resist merging with other particles. You can vary the amount of tension with the Variation value. The Tension value can range between 0.1 and 10 and the Variation can range from 0 to 100 percent.

Because MetaParticles can take a long time to render, the Evaluation Coarseness settings enable you to set how computationally intensive the rendering process is. This can be set differently for the viewport and the renderer-the higher the value, the quicker the results. You can also set this to Automatic Coarseness, which automatically controls the coarseness settings based on the speed and ability of the renderer. The One Connected Blob option speeds the rendering process by ignoring all particles that aren't connected.

Tutorial: Spilling soda from a can

MetaParticles are a good option to use to create drops of liquid, like those from a soda can.

To create liquid flowing from a can, follow these steps:

1. Open the  MetaParticles from a soda can.max file from the Chap 35 directory on the DVD. This file includes a soda can model created by Zygote Media positioned so the can is on its side.

2. Select the Create Particles Super Spray menu command, and drag the icon in the Front viewport. Position the icon so that its origin is at the opening of the can and the directional vector is pointing outward.

3. With the Super Spray icon selected, open the Modify panel, and in the Basic Parameters rollout, set the Off Axis and Off Plane Spread values to 40 .

4. In the Particle Generation rollout, keep the default Rate and Speed values, but set the Speed Variation to 50 to alter the speed of the various particles. Set the Particle Size to 20 .

5. In the Particle Type rollout, select the MetaParticles option, set the Tension value to 1 , and make sure that the Automatic Coarseness option is selected.

6. Open the Material Editor (by pressing the M key), and drag the Purple Soda material to the particle system icon.

Figure 35.10 shows a rendered image of the MetaParticles spilling from a soda can at frame 25.

Figure 35.10: MetaParticles emitting from the opening of a soda can

Instanced Geometry

Using the Particle Type rollout, you can select an object to use as the particle. If the Instanced Geometry option is selected as the particle type, you can select an object to use as the particle. To choose an object to use as a particle, click the Pick Object button and then select an object from the viewport. If the Use Subtree Also option is selected, then all child objects are also included.

The Animation Offset Keying option determines how an animated object that is selected as the particle is animated. The None option animates all objects the same, regardless of when they are born. The Birth option starts the animation for each object when it is created, and the Random option offsets the timing randomly based on the Frame Offset value. For example, if you have selected an animated bee that flaps its wings as the particle, and you select None as the Animation Offset Keying option, all the bees flap their wings in concert. Selecting the Birth option instead starts them flapping their wings when they are born, and selecting Random offsets each instance differently.

For materials, the Time and Distance values determine the number of frames or the distance traveled before a particle is completely mapped. You can apply materials to the icon that appears when the particle system is created. The Get Material From button lets you select the object from which to get the material. The options include the icon and the Instanced Geometry.

Rotation and Collision rollout

In the Rotation and Collision rollout is an option to enable interparticle collisions. This option causes objects to bounce away from one another when their object boundaries overlap.

The Rotation and Collision rollout, shown in Figure 35.11, contains several controls to alter the rotation of individual particles. The Spin Time is the number of frames required to rotate a full revolution. The Phase value is the initial rotation of the particle. You can vary both of these values with Variation values.

Figure 35.11: The Rotation and Collision rollout options can control how objects collide with one another.

You can also set the axis about which the particles rotate. Options include Random, Direction of Travel/MBlur, and User Defined. The Stretch value under the Direction of Travel option causes the object to elongate in the direction of travel. The User Defined option lets you specify the degrees of rotation about each axis.

Interparticle collisions are computationally intensive and can easily be enabled or disabled with the Enable option. You can also set how often the collisions are calculated. The Bounce value determines the speed of particles after collisions as a percentage of their collision speed. You can vary the amount of Bounce with the Variation value.

Tutorial: Basketball shooting practice

When an entire team is warming up before a basketball game, the space around the basketball hoop is quite chaotic -with basketballs flying in all directions. In this tutorial, we use a basketball object as a particle and spread it around a hoop. (Watch out for flying basketballs!)

To use a basketball object as a particle, follow these steps:

1. Open the  Basketballs at a hoop.max file from the Chap 35 directory on the DVD. This file includes basketball and basketball hoop models created by Zygote Media.

2. Select the Create Particles Super Spray menu command, and drag the icon in the viewport. Position the icon in the Front view so that its origin is above and slightly in front of the hoop and the directional vector is pointing down (you need to rotate the emitter icon).

3. Open the Modify panel, and in the Basic Parameters rollout, set the Off Axis Spread value to 90 and the Off Plane Spread value to 40 ; this randomly spreads the basketballs around the hoop. In the Viewport Display group of the Basic Parameters rollout, select the Mesh option. Set the Percentage of Particles to 100 percent to see the position of each basketball object in the viewport.

   Caution

   Because the basketball is a fairly complex model, using the Mesh option severely slows down the viewport update. You can speed the viewport display using the Bbox (Bounding Box) option, but you'll need to choose it after selecting the Instanced Geometry option.

4. In the Particle Generation rollout, select the Use Total option, and enter 30 for the value. (This number is reasonable and not uncommon during warm-ups.) Set the Speed value to 0.2 and the Life value to 100 because we don't want basketballs to disappear. Because of the low number of particles, you can disable the Subframe Sampling option. Set the Grow For and Fade For values to .

5. In the Particle Type rollout, select the Instanced Geometry option and click the Pick Object button. Make sure that the Use Subtree Also option is selected to get the entire group, and then select the basketball group in the viewport. At the bottom of this rollout, select the Instanced Geometry option and click the Get Material From button to give all the particles the same material as the original object.

6. In the Rotation and Collision rollout, set the Spin Time to 100 to make the basketballs spin as they move about the scene. Set the Spin Axis Control to Random. Also enable the Interparticle Collisions option, and set the Calculation Interval to 1 and the Bounce value to 100 .

   With the Collisions option enabled, the basketballs are prevented from overlapping one another.

7. At the floor of the basketball hoop is a Deflector Space Warp. Click the Bind to Space Warp button on the main toolbar, and drag from this floor deflector to the Super Spray icon.

   This makes the basketballs bounce off the floor.

Figure 35.12 shows a rendered image of the scene at frame 30 with several basketballs bouncing chaotically around a hoop.

Figure 35.12: Multiple basketball particles flying around a hoop

Object Motion Inheritance rollout

The settings on the Object Motion Inheritance rollout, shown in Figure 35.13, determine how the particles move when the emitter is moving. The Influence value defines how closely the particles follow the emitter's motion; a value of 100 has particles follow exactly, and a value of 0 means they don't follow at all.

Figure 35.13: The Object Motion Inheritance rollout sets how the particles inherit the motion of their emitter.

The Multiplier value can exaggerate or diminish the effect of the emitter's motion. Particles with a high multiplier can actually precede the emitter.

Bubble Motion rollout

The Bubble Motion rollout, also shown in Figure 35.13, simulates the wobbling motion of bubbles as they rise in a liquid. Three values define this motion, each with variation values. Amplitude is the distance that the particle moves from side to side. Period is the time that it takes to complete one side-to-side motion cycle. The Phase value defines where the particle starts along the amplitude curve.

Particle Spawn rollout

The Particle Spawn rollout, shown in Figure 35.14, sets options for spawning new particles when a particle dies or collides with another particle. If the setting is None, colliding particles bounce off one another and dying particles simply disappear. The Die After Collision option causes a particle to disappear after it collides. The Persist value sets how long the particle stays around before disappearing . The Variation value causes the Persist value to vary by a defined percentage.

Figure 35.14: The Particle Spawn rollout (shown in two parts) can cause particles to spawn new particles.

The Spawn on Collision, Spawn on Death, and Spawn Trails options all enable the spawn controls and define when particles spawn new particles. The Spawns value is the number of times a particle can spawn other particles. The Affects value is the percentage of particles that can spawn new particles; lowering this value creates some duds that do not spawn. The Multiplier value determines the number of new particles created.

The Chaos settings define the direction and speed of the spawned particles. A Direction Chaos value of 100 gives the spawned particles the freedom to travel in any direction, whereas a setting of 0 moves them in the same direction as their originator.

The Chaos Speed Factor is the difference in speed between the spawned particle and its originator. This factor can be faster or slower than the original. Selecting the Both option speeds up some particles and slows others randomly. You can also choose to have spawned particles use their parent's velocity or use the factor value as a fixed value.

The Scale Chaos Factor works similarly to the Chaos Speed Factor, except that it scales particles to be larger or smaller than their originator.

The Lifespan Value Queue lets you define different lifespan levels. Original particles have a lifespan equal to the first entry in the queue. The particles that are spawned from those spawned particles last as long as the second value, and so on. To add a value to the list, enter the value in the Lifespan spinner and click the Add button. The Delete button removes values from the list, and the Replace button switches value positions .

If Instanced Geometry is the selected particle type, you can fill the Object Mutation Queue with additional objects to use at each spawn level. These objects appear after a particle is spawned. To pick a new object to add to the queue, use the Pick button. You can select several objects, and they are used in the order in which they are listed.

Load/Save Presets rollout

You can save and load each particle configuration using the Load/Save Presets rollout, shown in Figure 35.15. To save a configuration, type a name in the Preset Name field and click the Save button. All saved presets are displayed in the list. To use one of these preset configurations, select it and click the Load button.

Figure 35.15: The Load/Save Presets rollout enables you to save different parameter settings.