Create and Use Variables for Anything

Blender is value-heavy, whether it is the position of a vertex, or the number of hair fibers in a particle system. Ideally, it should be possible to use the value of anything for the value of anything else through variables. For you programmers out there, this would be 'pass by reference' (i.e, pointer).

For example, the rotation of an object could be bound to the height of another object, or the position of a vertex could be based on the color of a material, etc. While these examples can be accomplished through other means, this feature would be robust enough to handle almost any scenario.

<h1>UX</h1> <ul><li><b>Creating a variable</b> — Just like keyframing, you would hover on the value and press 'v' (for variable). A pop-up would appear for you to specify a name for the variable. A default name could be generated based on information about the source field. For example, if it was the object's z-rotation field, the default name would be <i>"[objectname]_rotation_z"</i>.</li> <li><b>Using a variable</b> — In the target numerical field, clear it, then press space to get a list of variables. Type for the variable's name, then click one or press enter to use the first match.</li> </ul>

<h1>Variable Panel</h1> There would need to be a panel to manage these variables. It would handle the usual stuff, plus a couple neat things: <ul> <li><b>Management</b> — Standard management stuff like replacing all instances of a variable with another variable, creating independent variables, renaming, deleting, forking, etc.</li><li><b>Mapping</b> — See where a variable is being used. Drag a target from one variable's list to a different variable to re-map it to the new one.</li> <li><b>Math</b> — Variables are even better if you can do math with them. You could redefine the value of the variable using typical programming math syntax, and include other variables in the math.</li> <li><b>Object Access</b> — Through dictionary and 'self' notation, you would be able to use any of an object's values in the variable definition once you establish the link. This is to avoid having to create a variable for every property you want to use that has the same source. For example, if you want to create a variable that is "x + z", you could create 1 variable with the definition "self.dimensions.x + self.dimensions.z", rather than creating 3 variables (x, z, sum).</li> <li><b>Options</b> — Specify if the value is absolute, or can be affected by other things, such as modifiers, scaling, etc. Conceptually, you are controlling if the variable is the starting, intermediate, or final value.</li> </ul>

<h1>Other Notes:</h1> <ul> <li><b>Works at the Vertex Level</b> — This use-case was the inspiration for this feature; I wanted a way to have a vertex's location always be directly between two other vertices, plus an offset. Currently, it is awkward to accomplish. I wanted this mainly for rigging purposes.</li> <li><b>makeRelative()</b> — Related to the above, this function would allow you to quickly define a property for the selection based on a value or logic. For example, you could select random vertices, then lock their relative locations to each other. This kind of functionality requires this variable infrastructure.</li> <li><b>Living Variable Names</b> — If the variable name was auto-generated, it is 'living', so if you change the object's name, the variable's name updates.</li> <li><b>Animatible</b> — Variables should be animatible. This means you can set specific definitions of the value like keyframes, then specify the interpolation method/function. Alternatively, you could just include a time-affected value in your calculation.</li> </ul>

<h1>Why</h1> <ul> <li><b>Rigging</b> — I found that certain rigging scenarios are simplified with variables (plus math). You could have a bone's location or properties depend on other things, beyond what the current bone-constraints let you accomplish.</li> <li><b>Dynamism</b> — Rigs and objects can be more dynamic when their mesh or features are controlled via variables. You could configure a part of a mesh with a single variable instead of constraints or other tricks.</li> <li><b>Mesh Control</b> — Something as simple as making sure every cross-piece in a loop stays the same length no matter what is currently hard to achieve, and similar corner-cases.</li> <li><b>Fake Physics</b> — Like the above example, you can fake certain physics effects with variables, such as locking the length of certain edges, but allowing others to deform (looks like stretching).</li> </ul>

I have not included a mock-up as the UX component is straight-forward. I encourage you to think of scenarios where defining or linking values would help you; I find myself constantly wanting it.