Essential Blender- P5

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Nội dung Text: Essential Blender- P5

Duplication Back to our atomic example. To make the little atom have the right stuff inside, it will need three protons and three neutrons. You could move the existing icospheres away from the 3D Cursor and add four more from the toolbox. Or, you could make use of what you already have. RMB select one of the icospheres, then press Shift-D. Shift-D duplicates the selected objects. The duplicate object is created at the location of the original object, and is put into Grab (move) mode. Move the new object away from the original and press LMB to lock it into position. Note that pushing RMB to cancel Grab mode after duplication does not cancel the duplication. A duplicate will still have been made, but will be "hiding" at the exact location of the original. For that reason, if you accidentally duplicate an object, it's better to get into to the habit of moving it away from the original, LMB, then deleting it with the X-key. You need a total of six icospheres to make up the atom's nucleus. RMB select one of the icospheres you have so far. Next, use the B-key area selection method to select the other two as well. If you accidentally select the camera or lamp object, you can remove them from the selection by holding down the Shift key and RMB (probably twice) on them until they are no longer outlined in pink. Alternatively, you can press the A-key twice (once to select All, and again to deselect everything), then begin from scratch. When you have the three icospheres (and nothing else) selected, press Shift-D to duplicate all three at once. Using different views (Numpad 1,3,7 and MMB drag), the Grab/move tool and the x, y and z movement constraint hotkeys (or the manipulators!), move the six icospheres together to form a nice, messy, nucleus. It doesn't matter if it matches the illustration or not. The point is for you to start to become familiar with the tools you will be using all the time. Tip: Shift-D duplicates selected objects.
Figure 1.9: The completed nucleus. Moving On At this point, it's best to spell out what goals we would like you to accomplish to get the big picture. You still need to add three electrons and animate them so they fly around the nucleus. It would also be nice to add some sort of animation to the nucleus as a whole, so it's not just sitting there in quantum laziness the entire time. Before you begin animating, you should adjust your workspace to one more suitable to the task than the one you've been using up to this point. Do you remember from the Interface chapter that Blender's workspace is highly configurable, and that the default installation comes with several different screens, each suited to a different task? Now's the time to start making use of it. Use the Ctrl-Left Arrow hotkey to change working screens. If you are using the default Blender installation, this hotkey will have placed you in a screen labeled "1-Animation". Alternately, and a little more slowly, you could have chosen that option from the Screens drop down in the main header.
Figure 1.10: Choosing the Animation screen from the header.
Figure 1.11: The default Animation screen. Lots of new stuff here, but no need for panic. In fact, the only really important stuff you'll be dealing with right now is the timeline, the 3d view (which you already know), and something called the Ipo view.
Figure 1.11.1 The Timeline window. The timeline is pretty self-explanatory. It is the timeline in seconds over which your animation takes place. Controls on the timeline are simple as well. Start and End represent the start and end frames of the animation, and can be changed by clicking on them and entering new values. The "play" button plays your animation in the 3D view. Pressing it again halts animation. The "skip to start/end" buttons do exactly as advertised. LMB dragging within the timeline window plays through any animation you have created in other windows. Moving through an animation by dragging the mouse over a timeline is known as "scrubbing". The timeline can display either seconds or frames. With the cursor over the Timeline window, the T-key toggles between these display methods. Press the T-key and choose "Frames" for now. (If you're completely new to animation and need an explanation of time in animation and what the term "frame" means, check out the "Frames and Time" sidebar.) Frames and Time
In animation (and television and film), time is divided into Frames. Each frame is a still image that represents a slice of time. When played one after the other quickly enough, these individual frames give the illusion of motion. Different media have different frame rates. For most film productions, each second in time is divided into 24 frames. The common terminology is to say that film runs at 24 frames per second. For North American television (NTSC), the rate is 30 frames per second (fps). For European TV (PAL format), the rate is 25 fps. It is important that you know your target media before you begin to animate, as changing the frame rate mid-way through an animation can lead to poor results, as objects and effects animated at a different frame rate will appear unnatural. Empties Sometimes, it would be nice to create an object that you can animate or use as a reference, but that you won't need to render. A simple mesh could be used, but it would be even more efficient if there was a type of "placeholder" object. What would something like that be useful for? Well, let's say that you would like to make the entire nucleus of your atom pulsate (shrink and grow repeatedly). Since the nucleus consists of a number of objects, you would like to have a way to only animate such an effect once, as opposed to animating each object individually. In Blender, placeholders to help with such things are called Empties. You create an Empty object, then animate it to grow and shrink. Afterward, you get all the parts of your nucleus to follow that animation. Let's add an Empty to your Scene. First, to make sure that you can see it clearly when it's created, LMB somewhere away from the icospheres, setting the 3D cursor. Then, use the toolbox to Add->Empty. The Empty appears at the location of the 3D cursor, like any other new object.
Figure 1.12: The toolbox, about to add an Empty to the scene. Now, let's do your first bit of animation. In Blender, as in most 3D animation programs, animation is accomplished by changing the location, rotation or scale of an object over time. The markers that keep track of these changes are called Keys. In the Timeline window, make sure that the green time marker that indicates the current time is as far left as it will go. This should put you on Frame 1 of your animation. Move the cursor over the 3D window and press the I-key. A menu titled "Insert Key" pops up. Choose "Scale" from the menu, as you are going to only animate the scale of this empty.
Figure 1.13: The Insert Key menu, prepared to set a Scaling key. Back in the Timeline window, LMB around frame 80, setting Blender's frame counter to 80. Over the 3D window, press the S-key and scale the Empty up to twice its original size. LMB to confirm the change in scale. Now, press the I-key again and choose "Scale." You will notice that the timeline now contains two small yellow lines, one at the location in time of each key you just set (i.e. one at frame 1, and one around frame 80). Use the LMB to scrub the timeline between these two yellow markers. Watch the 3D view as you do it. You will see the Empty change scale as you scrub back and forth. As you can see, the Start and End frames for your animation are set to the defaults of 1 and 250, and you need to set a few more keys to fill out the space. Continue positioning the frame counter in the timeline with LMB, then scaling the Empty and inserting Scale keys for it. As you will see, fewer keys in the timeline will result in slower animations, while dense groupings of keys will lead to rapid changes. Remember to press the timeline's play button to have Blender play back your animation for you. Really, it doesn't matter how many keys you insert, or how you decide to scale the empty in this step. If you're the kind of person that needs detailed Instructions though,
try setting a new key every twenty frames, alternating between a large scaled empty and a small scaled one. Note: Another popular method of playing back your animation is to position the cursor over the window you would like to see animated (most likely the 3D view), and pressing Alt-A. Pressing Alt-Shift-A will accomplish the same thing, but will run the animation in all windows on the current screen. Now you have your Empty shrinking and growing. In the next step, you'll connect the spheres of your nucleus to it. Tip: I-key brings up a menu of available properties on which to set animation keys. Alt-A plays animation in a particular window. Parenting In the real world, children inherit traits from their parents. In the world of 3D graphics, you can give your objects parent-child relationships. A child object will inherit certain characteristics (like scaling) from its parent: if the parent object scales, so will the child. The child can have its own characteristics -- it can move, rotate and scale on its own -- but anything that its parent does, it will do too. So, if you have an Empty with animated scaling like you just created, making that Empty the parent of your sphere nucleus objects should cause them to scale just like it. Before you do the next bit, let's make sure that nothing is selected. Press the A-key twice to clear any selections that are currently made. Use the method of your choice (RMB, B-key border) to select all the icospheres that make up the nucleus of your atom. Then, holding down the Shift key, RMB select the Empty. Note: Something we haven't mentioned before is the distinction between "selected" objects and the "Active" object. Notice how the Empty, which was selected last, is a brighter shade of pink than the other selected objects? This brighter selection indicates that the Empty is the "Active" object. The Active object will always be the last one that you select. Having an Active object is important when you will be performing an operation (like Parenting) in which one or more objects will be linked or referenced in some way to a target object. That target will always be the Active object. So, with all of your icospheres selected, and with the Empty as the Active object, press Ctrl-P and click through the "OK? Make Parent" message that comes up.
Figure 1.14: The lines indicating a parent/child relationship are highlighted here. The icospheres are now the child objects of the Empty. In some tutorials and references other than this book, they are said to be "parented" to the Empty, even though they are its children. Although that is a common usage, it is technically inaccurate and counterintuitive so we will avoid it here. RMB select the empty, and use the G-key grab tool to move it around the 3D view (then RMB to cancel the move). The spheres move with it. Use the R-key to rotate the empty and see how the spheres move with it again (then RMB to cancel). RMB select one the icospheres and move it around by itself (don't forget to RMB to cancel the operation). Child objects can still be moved independently, but follow the motion of their parents. Press the Play button in the Timeline window (or Alt-A over the 3D view) to see how parenting has caused the icospheres to inherit the scaling animation of the Empty. Weird, huh? The icospheres grow and shrink with the Empty, but their distance from the Empty changes as well. That's not what you wanted. What is happening is that the children are changing size, but they are changing size as though they and the parent Empty are all one large object,
growing and shrinking overall. Let's change this so it works correctly. If you wanted to, you could repeatedly use Undo (Ctrl-Z) to back step until the parenting relationship is removed. Instead, select the icospheres and press Alt-P. An "OK?" menu pops up, with "Clear Parent" already selected. LMB to accept this (or you can press Enter on your keyboard for the same effect). The dashed lines that had been an indicator of the parent-child relationship have disappeared, showing that the spheres are no longer the children of the Empty. To get the correct effect this time, you would like to put the empty in the middle of your nucleus, so that when it grows and shrinks, the nucleus will follow it properly. You could just use the G- key to position the Empty somewhere near the middle, but there is a more accurate way. Tip: Ctrl-P creates a parent-child relationship between objects, with the Active object as the parent. Alt-P breaks the parent-child link of a selected child object. Snapping Select the icospheres of the nucleus. Press Shift-S. A "Snap" menu pops up, with five options. There are only two that you should really be concerned with: "Selection to Cursor" and "Cursor to Selection". Select "Cursor to Selection". This option places the 3D cursor at the center of the current selection.
Figure 1.14.1: The Shift-S snap menu. So, how do you get the Empty to the exact center of the nucleus? Select the Empty (only the Empty, nothing else!), press Shift-S and this time choose "Selection to Cursor". This option moves any selected objects to the location of the 3D cursor. You can see then that the workflow for precision movement in Blender is a two step process. First, position the 3D cursor via selection and Snap "Cursor to Selection". Then, Select the object you wish to position and Snap "Selection to Cursor". In the example above, you've used the Snap menu to position your animated Empty in the center of the nucleus icospheres. Use B-key to select the icospheres. The Empty, which was selected in the previous step, remains selected and is, in fact, the Active object, as you can see by its brighter color. (If the Empty is not the Active object, hold down the Shift key and RMB click it to make it so.) With the icospheres selected and the Empty as the Active object, press Ctrl-P to create a parent relationship.
Figure 1.14.2: The spheres are now the children of the Empty in the middle. Scrub the mouse back and forth in the timeline. This time, the scaling of the whole nucleus functions as you had hoped. At this point, if you wanted some extra practice, you could create a new Empty and animate it to pulse in a different fashion from the first. Then, you could make half the spheres the children of this new empty, leaving the others as the children of the original. This would create a more complex and hopefully more interesting animation. Tip: Shift-S brings up the Snap menu. Animation and Keys Let's get a little more acquainted with Blender's system for creating keys for animation. To do this, you will add an electron to your atom and make it travel around the nucleus.
Figure OT.15: Set the 3D cursor away from the nucleus. Before you do anything else, let's make sure that you are looking at your atom from the front - if you aren't, then some of the following examples will not quite work. Use Numpad-1 to go to a front view. LMB to the left of the nucleus, setting the 3D cursor there, so that your electron is created at a good location. Use the spacebar toolbox to add an icosphere. Remember to use the Tab key after the object is created, to get out of Edit Mode. Really, you can add any kind of object you choose to experiment with, but our illustrations will use the icosphere. With the S-key, shrink the icosphere so it's a bit smaller than the ones already in the nucleus. Make sure Blender's frame counter is set to 1 (use the Timeline view for this) and that only the electron is selected. Press the I-key and choose "Loc" (Location) from the Insert Key menu that pops up.
Figure 1.15.1: A new icosphere added to be the first electron. LMB in the timeline to set the frame counter to somewhere around 60. Use G-key to move the electron to a position above the nucleus in the 3D view. Insert another location key. Skip ahead to around frame 120, move the electron to the right of the nucleus and insert a location key. Finally, skip to around frame 180, move the electron below the nucleus and insert a key.
Figure 1.16: The position of the electron at different frame numbers. Press the play button in the timeline or use Alt-A over the 3D view to play your animation. Tip: I-key brings up the Insert Key menu, which lets you set animation keys for the Active object. You'll see that this animation is not satisfactory for two reasons. First, the electron follows more of a diamond shaped path around the nucleus than a circle. Second, the electron stops below the nucleus, instead of continuing back through to its starting point. First, let's round out the path that the electron follows. With the electron selected, press the K- key. Three olive-colored copies of the icosphere appear, one at each of the locations where we had set a key. The K-key toggles the display of keys in the 3D view. Scrub with the LMB in the timeline until the electron is halfway between the left and upper keys.
Figure 1.17: The electron should be here to make a nice circular path. If you try to use the G-key at this point, you will find that the icosphere does not move. This is because in this key view mode your transformations like move, rotate and scale only work on already set keys, not the actual object. So, let's add a new key here, then move it to create a better circular path. Use I-key, and select "Loc" as before to insert a new key. Then with the G-key, move the key up and to the left. You will see the electron object move too, but this is only a result of moving the key. You are not moving the electron directly. Now, as you scrub back and forth in the timeline, you can see the motion for this part of the animation is much closer to circular. Using LMB to move through the timeline, set new keys halfway between the other keys that have already been set, moving them slightly to make the entire animation more circular.
Figure 1.18: The new key positions are highlighted. You have fixed the first problem with your animation. As you're finished with Key mode for the moment, use the K-key to exit that mode, hiding the keys in the 3D view. Let's move on to the second problem, which is that you would like the electron to end in the exact place it begins. Tip: K-key toggles Key mode in the 3D view, which allows you to see and adjust key transformations directly. Working in the Ipo Window
Figure 1.19: The Ipo window with curves from the orbiting electron. Let's finally take a look at the Ipo window, shown in the illustration. The first thing to do is to make sure that your orbiting electron is selected in the 3D view. Then, place the mouse over the Ipo window and press the Home key. Recall that in the 3D view, the Home key zooms and translates the view so that every existing object becomes visible. It does the same thing in the Ipo window.
Figure 1.20: The Home key auto-zooms and pans a window to show everything. The curves in this window represent the object's motion through space. You can see that there are three curves, each color coded to match one of the labels on the window's legend at the right. (If instead of colored curves you see a bunch of vertical yellow lines and gray curves, press the K- key. We'll explain in a moment.) If you look along the bottom of the Ipo window, the ascending numbers indicate frames. Along the left side of the window is another scale that indicates values (locations in this case). So, LMB somewhere in the Ipo window to move the frame counter to that frame, just like the Timeline window. Use LMB to place the frame indicator line near frame 50. The legend on the right of the window tells you that LocZ (Location on the Z axis) is represented by yellow. In the Ipo window, then, find where the vertical frame indicator crosses the yellow curve. Look to the left-hand scale to see the approximate value of that orange curve at the intersection. In the illustration, it appears to be around seven.