target="_blank" rel="nofollow" href="#fb3_img_img_0d66d43f-23c1-59d3-b57f-32582aa3fc30.png" alt="Tip"/> If you’re coming from another 3D program, you may find the way Blender handles coordinates a bit disorienting. Blender uses what’s known as a “right-handed, Z-axis up” convention. Some programs (such as Cinema 4D and Maya) have the Y-axis representing vertical movement and the Z-axis going from front to back. And still other programs have either Z or Y as the vertical axis, but oriented in a left-handed convention. Currently, you can’t change the coordinate system in Blender to match any of these programs, so the right-handed, Z-up system is one of those things that migrating users just need to get used to.
FIGURE 3-1: The Transform Orientations menu from the 3D Viewport’s header (left) and when invoked as a pie menu by pressing the Comma (,) hotkey.
As Figure 3-1 shows, you can choose from six orientations: Global, Local, Normal, Gimbal, View, and Cursor. Working in any of these coordinate systems gives you absolute control of how your object lives in 3D space. Depending on how you’d like to transform your object, one orientation may be more appropriate than the others. Blender also gives you the ability to create custom orientations. That topic is slightly more advanced than I have room to cover in this book, but after you create a custom orientation, it also becomes available on the Transform Orientations menu.
Global: You see this orientation of Blender’s base grid in the 3D Viewport. In many ways, the Global orientation is the primary orientation to which everything else relates, and it’s the base coordinate system described at the beginning of this section. The Z-axis, marked in blue, runs vertically in the space. The Y-axis is marked in green, moving along the front-to-back line, and the X-axis is in red, along the side-to-side line. The origin is located directly at the center of the grid.
Local: In addition to the Global orientation, each 3D object in Blender has a local coordinate system. The base of this system isn’t the same as the Global coordinate system’s base. Instead, this coordinate system is relative to the center point, or origin, of your object. The object origin is represented by the orange dot that’s usually located at the center of your 3D object. By default, when you first add a new object in Blender, its Local coordinate system is aligned to the Global axis, but after you start moving your object around, its Local coordinate system can differ greatly from the Global orientation.
Normal: The Normal orientation is a set of axes that’s perpendicular to some arbitrary plane. When working with just objects, this description doesn’t really apply, so the Normal orientation is exactly the same as the Local orientation. When you begin editing meshes, though, Normal orientation makes more sense because you have normals (imaginary lines that extend perpendicular to the surface of a triangle or plane) to work with. Blender also uses the Normal orientation for the local coordinate system of bones when working with armatures for animation. A nice way to think about the Normal orientation is the “more local than local” orientation. Chapter 4 covers editing meshes in more detail, and Chapter 12 covers working with armatures in depth.
Gimbal: When you rotate an object about its X-, Y-, and Z-axes, the angles about those axes are known as Euler (pronounced like oiler) angles. Unfortunately, a side effect of using Euler angles is that you have the possibility of running into gimbal lock. You run into this problem when one 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.
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.
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.
Activating object gizmos
Figure
