The bomb spacewarp is often good for quick explosions, however, close inspection reveals paper thin pieces of debris that simply fall through floors and cannot be acted upon by other forces. If an explosion requires debris and some control over the pieces a PArray (Particle Array) can help. The PArray can create explosive visuals and allow forces, such as gravity, wind, and deflectors to act upon the pieces.
Part One - Creating A Box And A PArray
1. Create a simple box with 3x3x3 length, width, and height segments. This will allow the box to explode with an ample number of particles. Refer to the Explode A Box tutorial if you are unsure how to do this.
Next, you will create a PArray. This can be accomplished by going to the Command Panel and selecting the Create | Geometry | Particle Systems | Parray option.
2. Draw the PArray as though you were creating a box. It does not matter where the PArray is placed in the scene as it is only a placeholder. It does not render out and the scene does not effect anything in relation to where it is. What matters most is the many modifications that can be employed to create a seemingly 'chunky' explosion based on an original source object.
Examine the option windows that are available by making sure that the PArray is active and then selecting the Modify tab. As with all options, the further down the list, the more CPU intensive the task. Not all options will be employed in this tutorial and a lot of tweaking and experimentation can take place after the main part of the tutorial is completed.
3. Start with the Basic Parameters. Use the Pick Object button to select the box created earlier. Afterwards, choose Mesh in order to view the particles created in the viewport.
4. Under Particle Generation, lower the speed to 0 (ZERO). You can use the default speed, but you will have more control over the debris using Spacewarps, such as wind, gravity, and deflectors.
5. Just as the bomb has an option to control when the explosion should occur, the PArray also allows you to control when it starts, ends, and how long it should live for. Defaults are fine for now, but you may want to give yourself some breathing room by moving the start time to 10. Also, the particles should probably live for as long as your animation. So if you are using the default of 100 frames. Make the life 100.
6. Under the Particle Type rollout, make sure that Object Fragments is chosen in order to create debris.
7. Your particles can be given a particular material by placing it on the icon representing the PArray. However, if you woudl like your PArray to take on the qualities of the object it is created from, you can select to obtain the material from the Picked Emitter.
8. Finally, under Rotation and Collision a spin can be created. The spin must be set to 1, but by animating the Variation you can slow down the spin over time and even stop it. At this point you should be able to see your box break apart, but the pieces will be spinning in their place. In order to move the fragments in a particular direction, their is a need to add Spacewarps to the scene.
Part Two - Adding Spacewarps
Spacewarps can be powerful tools. If you have already completed the Explode A Box tutorial, you know that the bomb spacewarp is bound to a target. In this case, several spacewarps will be bound to the PArray in order to create movement and interaction with its immediate surroundings.
9. Select the Create | Spacewarp | Forces | Wind
10. Wind has two main options, its strength and whether it is directional or omni-directional. The strength starts at 1 (or full) and can be turned to 0 (or off). The planar vs spherical option allows you to choose a particular direction that the wind blows or simply away from a central point, respectivly. The placement of the wind in relation to the object it will be bound to is important. If you place the wind in the centre of the object it will disperse its pieces in all directions. If the wind is off to the left, the pieces will fly away to the right.
11. Bind The Spacewarp to the PArray. This can be done by binding it to the icon representing the box, or it could be attached to any of the pieces.
12. Create a Plane underneath the box. This plane provides a visual cue for the debris to bounce off of.
13. Create a Deflector by choosing Create | Spacewarp | Deflectors | Deflector
14. Use the Bind To Spacewarp tool to bind the Deflector to the PArray.
15. Finally, add some gravity to your scene and associate that with the PArray as well. This will help bring the pieces of debris back down after it bounces off the Deflector. At this point you should have a PArray using a box to emit from, Wind to blow the pieces created away, and a Plane that has a Deflector in the same place, but associated with the PArray in order to make it appear to bounce off the plane. If you select the PArray and select the Modify tab, you should see the following:
The image shows that the original PArray is being affected by the three Spacewarps.
Part Three - Invisibility
This last section is in response to the obvious problem of the box remaining visible, even after the PArray's debris is thrown from the exact location. In order to finish this illusion, the box needs to be made invisible at the frame it is destroyed. If the box is to be destroyed at frame 10, then the box should disappear at the same frame.
16. Open the Track View option by selecting the Graph Editors from the top menu options and choosing Track View | Open Track View from the flyout.
The Track View holds information about everything related to the current scene. It can be quite complex, however, in this case the only thing we are concerned with is the Visibility Track of the box.
17. Scroll down and expand the Objects | Box01 flyouts. Notice that there are several options in this catagory, but nothing realted to visibility. In order to activate this track you need to select the eyeball [
] on the Track View menu. Once depressed, the eyeball becomes greyed out and a visiblity track is provided. Add two keys to the Visibility Track by selecting the create key button, [
]
18. The first key should set the visiblity of the box to 1 (or full) and a second key should be set at the same frame the PArray becomes active. The second key should be set to 0 (or off). Keys can be edited by right clicking on them.
19. This last information pertains to how the animation should play out. For example, should it make a smooth transition from visible to invisible? Or should it simply change invisible at a particular frame? For this project, it is necessary that the box simply turn invisible immediately. Change the animation choice to the staircase. This will make a sudden change occur rather than a gradual one.
By playing back the current animation you should have something similar to what is shown below. A more complicated scene involving photographs can produce some realistic damage.