512 Part III Modeling

The surface tools, which include the CrossSection and Surface modifiers, provide another way to model that is similar to lofting. The CrossSection modifier takes several cross-section shapes and connects their vertices with additional splines to create a spline framework. You can then use the Surface modifier to cover this framework with a skin.

Although similar in nature, Loft objects and the surface tools have different subtleties and strengths.

One difference is that the CrossSection modifier connects spline cross sections according to their order. This can cause strange results if the order is incorrect. A Loft always follows a path, so the cross-section order isn’t a problem.

Another difference is that surface tools give you more control over the surface of a created object. Because the underlying structure is a series of splines, you can add new branches and objects without much difficulty. This can be hard to do with Loft objects.

As a general guideline, Loft objects are better suited to modeling rigid objects with relatively uniform cross sections, whereas the surface tools are better for modeling more organic model types.

Summary

Compound objects provide several additional modeling types to our bulging modeling toolkit. From morph objects to complex deformed lofts, you can use these special-purpose types to model many different objects. In this chapter, you

Learned about the various compound object types

Morphed objects with the same number of vertices

Created a Conform object with differing numbers of vertices

Used splines and mesh objects to create a ShapeMerge object

Created a Terrain object using splines

Learned about the Mesher object

Used the BlobMesh object to simulate water

Created a Scatter object

Created a Connect object to join two objects

Modeled with Boolean objects

Created a Loft object

Discovered how to control Loft parameters

Learned to use Loft deformations

Modified Loft subobjects

Compared the strengths of loft objects versus surface tools

With all these different modeling types, you’ve probably started to create lots of different objects, but get ready to really start creating lots with particle systems.

Creating Particles

and Particle Flow

Every object that you add to the scene slows down Max to a small degree, because Max needs to keep track of every object. If you

add thousands of objects to a scene, not only does Max slow down noticeably, but the objects become difficult to identify. For example, if you had to create thousands of simple snowflakes for a snowstorm scene, the system would become unwieldy, and the number wouldn’t get very high before you ran out of memory.

Particle systems are specialized groups of objects that are managed as a single entity. By grouping all the particle objects into a single controllable system, you can easily make modifications to all the objects with a single parameter. This chapter discusses using these special systems to produce rain and snow effects, fireworks sparks, sparkling butterfly wings, and even fire-breathing dragons.

Understanding the Various

Particle Systems

A particle is a small, simple object that is duplicated en masse, like snow, rain, or dust. Just as in real life, Max includes many different types of particles that can vary in size, shape, texture, color, and motion. These different particle types are included in various particle systems.

When a particle system is created, all you can see in the viewport is a single gizmo known as an emitter icon. An emitter icon is the object (typically a gizmo, but it can be a scene object) where the particles originate. Selecting a particle system gizmo makes the parameters for the particle system appear in the Modify panel.

Max includes the following particle systems:

Spray: Simulates drops of water. These drops can be Drops, Dots, or Ticks. The particles travel in a straight line from the emitter’s surface after they are created.

Snow: Similar to the Spray system, with the addition of some fields to make the particles Tumble as they fall. You can also render the particles as a Six Pointed shape that looks like a snowflake.

18C H A P T E R

In This Chapter

Understanding the various particle systems

Creating a particle system

Using the Spray and

Snow particle systems

Using the Super Spray and Blizzard particle systems

Working with

MetaParticles

Using an object as an emitter

Using particle system maps

Using the Particle Flow interface

514 Part III Modeling

Blizzard: An advanced version of the Snow system that can use the same mesh object types as the Super Spray system. Binding the system to the Wind Space Warp can create storms.

PArray: Can use a separate Distribution Object as the source for the particles. For this system, you can set the particle type to Fragment and bind it to the PBomb Space Warp to create explosions.

PCloud: Confines all generated particles to a certain volume. A good use of this system is to reproduce bubbles in a glass or cars on the road.

Super Spray: An advanced version of the Spray system that can use different mesh objects, closely packed particles called MetaParticles, or an instanced object as its particles. Super Spray is useful for rain and fountains. Binding it to the Path Follow Space Warp can create waterfalls.

Particle Flow Source: Particles that can be defined using the Particle Flow window and controlled using actions and events.

Creating a Particle System

You can find all the various particle systems under the Create panel and also in the Create menu. To access these systems, click the Geometry category and select the Particle Systems subcategory from the drop-down list. All the particle systems then appear as buttons. Or you can select the Create Particles menu.

With the Particle Systems subcategory selected, click the button for the type of particle system that you want to use, and then click in a viewport to create the particle system emitter icon. The emitter icon is a gizmo that looks like a plane or a sphere and that defines the location in the system where the particles all originate. Attached to the icon is a single line that indicates the direction in which the particles move when generated. This line points by default toward the construction grid’s negative Z axis when first created. Figure 18-1 shows the emitter icons for each particle system type including, from left to right, Particle Flow Source, Super Spray, Spray and Snow and Blizzard (which all have the same emitter icon), PArray, and PCloud.

Figure 18-1: The emitter icons for each particle system type

You can transform these icons using the standard transform buttons on the main toolbar. Rotating an emitter changes the direction in which the particles initially move.

After an icon is created, you can set the number, shape, and size of the particles and define their motion in the Parameter rollouts. To apply a material to the particles, simply apply the material to the system’s icon. This material is applied to all particles included in the system.

Note	Be aware that the particles are displayed as simple objects such as ticks or dots in the view-
	ports. To see the actual resulting particles, you need to render the scene file.

Chapter 18 Creating Particles and Particle Flow

515

You can set the parameters for the Max particle systems in the Create panel when they are first created or in the Modify panel at any time. The simpler systems, Spray and Snow, have a single Parameters rollout, but the advanced systems — Particle Flow Source, Super Spray, and Blizzard — include multiple Parameters rollouts. The PArray and PCloud systems have similar multiple rollouts, with a few subtle differences, and the Particle Flow system includes several rollouts, but most of the action is with the Particle Flow window. The following sections describe how to use these rollouts to set the parameters for the various particle systems.

Using the Spray and Snow Particle Systems

All I can say about the Spray and Snow particle systems is that “when it rains, it pours.” The Spray Parameters rollout, shown in Figure 18-2, includes values for the number of particles to be included in the system. These values can be different for the viewport and the renderer. By limiting the number of particles displayed in the viewport, you can make the viewport updates quicker. You can also specify the drop size, initial speed, and variation. The Variation value alters the spread of the particles’ initial speed and direction. A Variation value of 0 makes the particles travel in a straight line away from the emitter.

Figure 18-2: The Spray Parameters rollout holds the parameters for the Spray particle system.

Spray particles can be Drops, Dots, or Ticks, which affect how the particles look only in the viewport. Drops appear as streaks, Dots are simple points, and Ticks are small plus signs. You can also set how the particles are rendered — as Tetrahedron objects or as Facing objects (square faces that always face the viewer).

Note	The Facing option is visible only in the Perspective view.

The Timing values determine when the particles appear and how long the particles stay around. The Start Frame is the first frame where particles begin to appear, and the Life value determines the number of frames in which the particles are visible. When a particle’s lifetime is up, it disappears. The Birth Rate value lets you set how many new particles appear in each frame; you can use this setting or select the Constant option. The Constant option determines the Birth Rate value by dividing the total number of particles by the number of frames.

516 Part III Modeling

The emitter dimensions specify the width and height of the emitter gizmo. You can also hide the emitter with the Hide option.

Note	The Hide option hides the emitter only in the viewports. Emitters are never rendered.

The parameters for the Snow particle system are similar to the Spray particle system, except for a few unique settings. Snow can be set with a Tumble and Tumble Rate. The Tumble value can range from 0 to 1, with 1 causing a maximum amount of rotation. The Tumble Rate determines the speed of the rotation.

The Render options are also different for the Snow particle system. The three options are Six Point, Triangle, and Facing. The Six Point option renders the particle as a six-pointed star. Triangles and Facing objects are single faces.

Tutorial: Creating rain showers

One of the simplest uses for particle systems is to simulate rain or snow. In this tutorial, you use the Spray system to create rain and then learn how to use the Snow system to create snow.

To create a scene with rain using the Spray particle system, follow these steps:

1.Open the Simple rain.max file from the Chap 18 directory on the CD-ROM. This file includes an umbrella model created by Zygote Media.

2.Select the Create Particles Spray menu command, and drag the icon in the Top viewport to cover the entire scene. Position the icon above the objects, and make sure that the vector is pointing down toward the scene objects.

3.Open the Modify panel, and in the Parameters rollout, set the Render Count to 1000 and the Drop Size to 2. Keep the default speed of 10, and select the Drops option; these settings make the particles appear as streaks. Select the Tetrahedron Render method, and set the Start and Life values to 0 and 100, respectively.

Note	To cover the entire scene with an average downpour, set the number of particles to 1000 for
	a 100-frame animation.

4.Open the Material Editor (by pressing the M key), and drag a light-blue-colored material to the particle system icon.

Figure 18-3 shows the results of this tutorial.

Tutorial: Creating a snow storm

Creating a snowstorm is very similar to what you did in the preceding tutorial. To create a snowstorm, use the Snow particle system with the same number of particles and apply a white material to the particle system.

Chapter 18 Creating Particles and Particle Flow

517

Figure 18-3: Rain created with the Spray particle system

To create a scene with snow using the Snow particle system, follow these steps:

1.Open the Snowman in snowstorm.max file from the Chap 18 directory on the CD-ROM. This file includes a snowman created using primitive objects.

2.Select the Create Particles Snow menu command, and drag the icon in the Top viewport to cover the entire scene. Position the icon above the objects, and make sure that the vector is pointing down toward the scene objects.

3.Open the Modify panel, and in the Parameters rollout, set the Render Count to 1000 and the Flake Size to 6, and use the Six Point Render option. Select the Start and Life values to 0 and 100, respectively.

4.Open the Material Editor (by pressing the M key), and drag a white-colored material with some self-illumination added to the particle system gizmo.

Figure 18-4 shows the results of this tutorial.