Blender For Dummies. Jason van Gumster

of your rotation axes matches another one. For example, if you rotate your object 90 degrees about its X-axis, then rotating around its Y-axis is the same as rotating about its Z-axis; mathematically speaking, they’re locked together, which can be a problem, especially when animating. This orientation mode in Blender helps you visualize where the axes are, so you can avoid gimbal lock.

        View: The View orientation appears relative to how you’re looking at the 3D Viewport. Regardless of how you move around in a scene, you’re always looking down the Z-axis of the View coordinate system. The Y-axis is always vertical, and the X-axis is always horizontal in this orientation.

        Cursor: In Chapter 2, I cover the use of Blender’s 3D cursor for adding objects and using it as a reference when modeling. You can also use the 3D cursor’s orientation as a reference to transform orientation by selecting this option from the Transform Orientations menu.

      

All these coordinate-system explanations can be (please forgive the pun) disorienting. An easy way to visualize this concept is to imagine that your body represents the Global coordinate system, and this book is a 3D object oriented in space. If you hold the book out in front of you and straighten your arms, you move the book away from you. It’s moving in the positive Y direction, both globally and locally. Now, if you twist the book to the right a few degrees and do the same thing, it still moves in the positive Y direction globally. However, in its local orientation, the book is moving in both a positive Y direction and a negative X direction. To move it in just the positive local Y direction, you move the book in the direction in which its spine is pointing.

To relate this concept to the View orientation, assume that your eyes are the View axis. If you look straight ahead and move the book up and down, you’re translating it along the View orientation’s Y-axis. Gimbal orientation would be if you rotate the book 90 degrees toward you, rotating about its X-axis. Then its Y- and Z-axes are locked together. For a clear reference, the 3D manipulator in Figure 3-2 shows the difference between the coordinate systems.

      FIGURE 3-2: The Global, Local, Normal, Gimbal, View, and Cursor coordinate orientations.

      

The last object you select is the active object. If you’re using the Local, Gimbal, or Normal orientations and select multiple objects, the transform operations happen relative to the active object’s orientation.

      

You can quickly change the coordinate system you’re using by using the Comma (,) hotkey to invoke a Transform Orientation pie menu.

Transforming an Object by Using Object Gizmos

      In Blender’s default configuration, there doesn’t appear to be a clear way to grab, scale, or rotate whatever you have selected. In other 3D applications, there are object gizmos, widgets, or manipulators that give you onscreen controls for transforming objects. Blender has them as well.

In all transform orientations under Blender, red represents the X-axis, green the Y, and blue the Z. If you think about the primary colors for light, a handy way to think of this is XYZ = RGB.

      Activating object gizmos

Figure 3-3 shows the various kinds of transform gizmos you have available in Blender.

      FIGURE 3-3: Blender gives you an assortment of transform tools: Move, Rotate, Scale, Scale Cage, and Transform.

      There are two primary ways that you can make transform gizmos visible in the 3D Viewport:

       Toolbar: The Toolbar along the left side of the 3D Viewport has four buttons for tools dedicated to transforming your objects. They’re located just below the Cursor tool. In order from top to bottom, they are as follows: Move: Also referred to as grabbing or translating. You get a set of colored axes at the origin of your object. Click and drag on the arrow of any axis to move your selection along it. Click and drag one of the squares between two axes and you can move your selection along the plane formed by those axes. Rotate: Choose this tool and you get a set of colored circles around your selected object’s origin. Click and drag one of the colored circles to rotate your selection about that axis. Scale: The default behavior that you get when you select this tool is a set of axes that look and behave very similar to those for the Move tool. However, if you hold down your mouse button when selecting this tool, you get access to another tool called the Scale Cage. With that tool, a box-shaped “cage” appears around your selection. Click and drag any point on the cage to scale in that direction. Transform: The Transform tool is a general-purpose tool that allows you to move, scale, or rotate without changing tools.The advantage of using the transform tools in the Toolbar is that you have quick access to them with a mouse, and their icons make it very clear what they do. Also, the Toolbar is the only way you can activate the Scale Cage tool. The downside of the tools in the Toolbar is that they can only be activated one at a time. If you want to move your object and then rotate it, you have to constantly go back to the Toolbar to change tools. This is alleviated somewhat with the general Transform tool, but that often shows more than you really want. Furthermore, in order to use any of these tools you have to stop using another tool (like any of the Select tools or any of the assorted tools available in Edit mode).

        Gizmos menu: There’s another option to give you the ability transform your selection in the 3D Viewport. The Gizmos menu in the header of the 3D Viewport, as shown in Figure 3-4, has a section devoted to object gizmos containing check boxes for Move, Rotate, and Scale. They’re all disabled by default, but if you enable any one of them, you’ll get a control gizmo that looks just like the corresponding one you get when activating one of the transform tools in the Toolbar. There are two distinct advantages to activating object gizmos this way:Multiple activation: You can activate any combination of gizmos. If you want to see just the Move and Rotate gizmos, just enable those check boxes. Enable them all and you get the same as the Transform tool. Or, as is the default, you can disable them so they’re not in your way at all.Always active: A key feature of the object gizmos approach is that they’re always there, regardless of what tool you’re using in Object mode or Edit mode. This approach saves you time because you’re not always switching between tools just to move your selection around (and then trying to remember what tool it was you were using before moving). Generally speaking, this means you end up working faster.The only real downsides of the Gizmos menu approach is that enabling and disabling gizmos is slightly slower because it requires an additional click to expand the Gizmos menu, and you don’t have access to the Scale Cage tool for scaling.

      Using object gizmos

      General usage for the object gizmos is described in the preceding section; however, there are some additional nuanced controls that you have while transforming your selection in the 3D Viewport.

      FIGURE 3-4: The Gizmos menu in the 3D Viewport’s header gives you the ability to activate transform gizmos