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In Getting Started with Reactor in 3ds Max, Steve Nelle shows how to create realistic dynamic simulations that have objects recognize, collide and react to coming into contact with each other in 3ds Max animation projects. This course includes a detailed explanation of both rigid and soft body dynamics, reactor's various collection types, using constraints and soft body modifiers, and how to adjust and control a dynamic simulation's accuracy. Four start-to-finish projects are also included in the course, which show practical techniques for breaking objects apart, creating cloth simulations, adding rippling water effects to a scene, and more. Exercise files accompany the course.
In a previous video, we described creating a collection as a method to identify and organize certain scene objects to be included in a simulation. We further stated that Reactor offered several different types of collections, with the collection type chosen determining just how that specific object, or objects, would respond or react to being run through a simulation. In this video, we'll take a closer look at working within the Collection framework using the Reactor toolbar that we've docked over on the left-hand side of our interface.
Let's first identify the five different types of collections you'll be working with when using Reactor. The first collection on the list, a Rigid Body Collection, is designed to house objects that will be seen as extremely hard and non-deforming during a simulation. A concrete floor or a hard dense piece of wood would be good examples of an object that might be added to a Rigid Body Collection, anything rock-solid and impenetrable. Just down from that, you've got the Cloth Collection, meant for surfaces that are intended to have the characteristics of--you guessed it--cloth.
Something like maybe a living room curtain or a blanket that would drape over a bed would be ideal candidates for a Cloth Collection. Third in line, the Soft Body Collection, is again one that's pretty easy to understand simply because of its name. What goes in it are things that are meant to be soft, a foam rubber cushion or maybe a beanbag for an example: any object that you might want to flex, bend or squash during a simulation. Rope Collections are designed to be used with splines or 3ds Max lines in other words, and they are meant to contain objects that take on more of a rope-like characteristic, which could easily include not just your standard braided rope or cord for something like a swing or tether pole, but also for simulating things like chains or even a character's long hair.
Now when creating a spline to be used in a Rope Collection, you've got to be careful as to the number and layout of your subobject vertices as they will have a substantial impact as to where and how realistic your rope type object will bend. So be sure to keep that in mind when making your original spline lines. Too few or poorly placed verts will no doubt hamper the believability of your simulated rope like objects. The last Reactor collection is known as a Deforming Mesh Collection, and it's a slightly different animal in comparison to all the other collection types as to how it works and what it's specifically designed to hold.
A Def Mesh Collection is a helper object that's designed to hold what Max refers to as a deforming mesh object, which in a nutshell is simply any mesh object whose vertices have already been animated. You'll many times see that vertex type animation on a character--maybe something or someone that's had its skin or muscles keyframed in one way or another. The cool thing about a Def Mesh Collection is it gives you the flexibility of having the surface of a deforming mesh object included in a dynamic SEM, being able to react to other objects in the simulation, yet at the same time still being able to maintain and not affect the original keyframing that's been done at its vertex level on its skin.
So in other words, Reactor doesn't recalculate the animation on an already animated object when that object is added to a simulation using a deforming mesh collection. So those are your five collection types. Let's now talk about how a collection is created and how something is added to a collection. Creating a collection is merely a point-and-click process. You select the type of collection that you want from the Reactor toolbar. Then you simply click on the screen where you want that collection located in your scene. Now, the actual position on the viewport where the collection is placed is not important.
The icon created, which doesn't render, merely serves as a placeholder or container on your screen in which to place objects. So if we render things up, you'll see how we still have nothing on the screen. Let's go ahead and create the other four collections. When a collection is selected, it grows in size and turns white. When not selected and when empty--in other words, when it contains no objects-- its icon will display on the screen in red.
An unselected collection that does contain at least one object will instead show itself in blue. We'll see that in just a moment. The settings and options in the Modify column are pretty much, for the most part, the same for each type of collection. You'll have a window that displays the scene objects that have been added to the collection and commands below the window for adding and removing scene elements. Now, to add something into a collection, there's a couple different ways you can go. With the Modify column open, you can easily pick an object out of your scene by simply clicking on the Pick button, then selecting the object.
If that object has been recognized by the collection, you'll then see its name in the list. You can also select an object or a series of objects simultaneously from a list. With a couple more teapots now in the scene, I've reselected my collection. In the Modify column, I'll then drop down to the Add button, then from the list, choosing my objects to add to the collection. Or another way to go, objects can automatically be added to a collection if those scene elements are first selected before the actual collection is created.
So with the new three green spheres, I'll ahead and select them, and again, I'll click on my Rigid Body Collection. The Collection icon will be automatically dropped directly in place with the objects in the collection. I'll go ahead and move that icon a little bit to the side. Back in the commands on the right, you can see what objects are currently included in any collection by simply clicking on the Highlight button. Objects included in the collection will momentarily display in white if using Wireframe mode, or with a bounding box around them if being viewed in Shaded mode.
Objects can also be easily removed from a collection by simply selecting its name in the list, then clicking on the Delete button. That name will no longer display and hitting the Highlight button will show that it's no longer included in that given collection. And you can quickly disable a collection, removing it from any upcoming simulations, by simply clicking Disable. If you no longer want a collection altogether, once the icon has been selected, you can simply hit the Delete key on your keyboard. The objects originally in that collection remain in the scene, ready to be put in another collection or left out of the simulation altogether.
Now, there are a couple of other things to keep in mind when working with collections. First, being added into a collection is an object's way of making sure to be included in a dynamic simulation, so being thrown into a collection is pretty much an object's ticket to getting into the game. Any object not in a collection won't be included or calculated into the simulation. Secondly, collections aren't mix and match. What I mean by that is only objects that are to behave similarly should be added to the same type collection.
A rigid body object for an example shouldn't be added to the same collection as a soft body object. One is designed to be rigid; the others are intended to be pliable. You got to keep similar objects together in their own collections. That's going to be very important to remember. So, rigid body objects go in one collection, a Rigid Body Collection, and soft body objects go on another collection, a Soft Body Collection. Make sense? Now a scene can have as many collections as needed, and any given collection can have as many objects in it as needed.
You just can't be mixing your apples with your oranges. Bottom line: different types of collections for different types of objects.
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