Explosion with Collision Animation 1

(exploding Teapot)

 

This tutorial shows you how to create an explosion with a meshed object, have the explosion fragments bounce off of a structure, and also covers a visibility track to make our "teapot" disappear after the fact. This tutorial assumes you know the basics of 3ds Max; ie, you can create boxes, apply materials, you can find your way around the Create panels, and you know how to do a boolean operation.

This is what we are going to create - a teapot that explodes into chunks, which collide with different models and bounce off of them realistically.

 

 

Here is the starting scene. This is simply a Teapot primitive and a simple room for the teapot to explode against. The teapot is a peace of cake because it's already made by 3ds Max. The room can be built in a few minutes by making a few box primitives and positioning them so that they overlap. Then boolean them together. There are three types of boolean operations - for this situation, use a boolean ADD. Of course you can use any kind of geometry you want for the explosion room, it just has to be "one piece".

 

 

On the Create panel, under Warps, you will need to add a UDeflector warp to the scene. This thing is just drawn, the same way a box is drawn. Set the Bounce to 1.0 (mine looks like 1,0 because I happen to be sitting in Sweden at this moment). Still hard for me to believe that a decimal for the Swedes is a comma. It doesn't matter where you put this deflector, so just place it in a handy-to-reach location for now.

 

 

Next, from the Create panel, under Objects, find Particle Systems. The kind of particle system we want to add is called a PArray. Place it anywhere handy - location is not critical. See the button that says Pick Object? Click that button and select the teapot, or whatever you are going to explode.

 

 

Now, from the Create panel, under Warps, find the Geometric / Deformable list. From this list, select Bomb. Unlike the last two objects we placed, the location of this one is important. Place it where you want the charge of the explosion to originate from. Don't get too sidetracked by the size and shape of the bomb, just be concerned about the center of it - that's the critical point that the explosion will originate from.

 

 

The next step works best if you are in the Top viewport and your screen is set to wireframe so you can easily select objects. In this screenshot, notice that there is a selected button on the Standard Toolbar. This button is called Bind To Space Warp. Activate this button, and use the left mouse button to select the bomb - then keep the left mouse button held down while you drag it to the PArray. When the cursor is directly over the PArray, release the mouse button. You have just bound the bomb to the PArray.

 

 

Do the same thing with the UDeflector. Use the Bind To Space Warp button to bind the UDeflector to the PArray. This screenshot shows what the screen should look like when you are done - if you select the PArray, you will see that it has two objects bound to it in the panel at right.

 

 

Now we will talk about settings. For the bomb, start with the settings I have above. Start time is the frame at which the bomb will go off. Duration is how long the explosion will last. Strength is how strong the explosion is. You can adjust the range but start with linear for now.

 

 

Now let's look at the UDeflector for a moment. You can see the settings we have started with - notice all are turned off except for Bounce. See the button that says Pick Object? Click that button, and then select your collision room, or whatever you want this particular explosion to bounce off of. My collision room is named Box04. Just make sure you select a real mesh object that is one-piece.

 

 

Next we will look at the settings for the PArray, which is really the key to getting this whole thing to work. The PArray has so many settings, I had to drag the Max menus way out so you'd to be able to see all of the critical ones. Here are the important settings: In the first rollout under Viewport Display, make sure Mesh is selected. In the Particle Generation rollout, under Particle Timing, copy my settings. In the Particle Type rollout, make sure Particle Types is set to Mesh, and Object Fragment Controls has a Thickness greater than 0, and Number of Chunks is set to something around 50. That should be all that is required for a simple working explosion with collisions.

 

 

Now drag the Time Slider and see what happens around frame 30-40. Hopefully it worked fine for you. Now, only one problem. The teapot exploded, but well after the explosion, there it sits, seemingly unfazed. What's going on here? The PArray made some fake explosion fragments for you, but the teapot itself remains intact. Our task now, to make this illusion complete, is to make the teapot disappear.

 

 

Select the teapot, right-mouse click, and choose Curve Editor from the right-button menu. This will launch the Curve Editor, a strange looking beast if you've never used it.

 

 

Use the explorer-like interface at the left to find your teapot. See how my teapot is selected with a yellow bar on the left? That's the first critical step here. Next, go to the Tracks pull down menu in the Curve Editor and select Visibility Track, then select Add from the flyout, just as shown above. This will add a nearly invisible dotted horizontal line at the zero point in the Curve Editor. Having this line added gives us the ability to Add Keys to the line, which is what we will do next.

 

 

Okay, now this is going to be tricky to explain. I hope those who are reading this have a little experience with the Curve Editor. You will need to adjust the image on the right so you can see that barely discernable horizontal line at the value "0". Notice my screen above - I have panned it and zoomed a bit so I can see that horizontal line - ie, the Visibility Track. Also note the selected button on the Standard Toolbar of the Curve Editor. This selected button is called Add Key. Click that button, and then click right on the Visiblity Track. You can see where I've done this three times in the screenshot above. I put one key at around frame 0, one around frame 30, and one around frame 100.

 

 

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Here, I've added yet another key at frame 28 or so. Here's how the Visiblity Track works: whenever the Visibility Track is above a value of "0", the object (the teapot in this case) is visible. Whenever the Visibility Track is under a value of "0", the object is invisible. So we just have to work it so the teapot becomes invisible when the explosion occurs. I've used another technique here to move the keys - you can see the button selected above, on the left, this is the Move Keys button. Once the keys have been created, you will almost always need to move them. It works just like the Move in 3ds Max.

 

 

If you have no material on your teapot, it will disappear in your viewport. If you have a material on your teapot, and did everything correctly, you may be disappointed to find that the teapot does not disappear in your viewport. However, once you render, you will see that the teapot is actually quite invisible. Notice in this screenshot that the teapot fragments are bouncing off of the walls of the explosion room, and that the thickness of the fragments makes them fairly believable.

 

 

Now we need to delete the "explosion room" and add some geometry to the scene. In this screenshot I created a big floor (just a box, really), a wall (another box), and a few cylinders. I positioned these models near the teapot so the chunks have something to collide with. I also created three new UDeflectors by cloning the original one three times.

 

 

In this screenshot the Bind Space Warp tool is used to bind the PArray to UDeflector2, then to UDeflector3, then to UDeflector4. Also, you need to select each UDeflector one at a time and click the Pick Object button that appears on the Modify Panel, and assign a model to each UDeflector. I assigned the Floor to UDeflector1, the Wall to UDeflector2, Cylinder1 to UDeflector3, and Cylinder2 to UDeflector4.

 

 

Here is the rendered image from halfway through the explosion, around frame 35.