************ Introduction ************ .. admonition:: Reference :class: refbox :Mode: Object or Edit Modes :Menu: :menuselection:`Add --> Meta` :Hotkey: :kbd:`Shift-A` *Meta* objects are *implicit surfaces*, meaning that they are *not explicitly* defined by vertices (as meshes are) or control points (as surfaces are): they exist *procedurally*. Meta objects are literally mathematical formulas that are calculated on-the-fly by Blender. A very distinct visual characteristic of metas is that they are fluid *mercurial*, or *clay-like* forms that have a "rounded" shape. Furthermore, when two meta objects get close to one another, they begin to interact with one another. They "blend" or "merge", as water droplets do, especially in zero-g (which, by the way, makes them very handy for modeling streams of water when you do not want to do a fluid simulation). If they subsequently move away from one another, they restore their original shape. Each of these is defined by its own underlying mathematical :doc:`structure `, and you can at any time switch between them using the *Active Element* panel. Typically *Meta* objects are used for special effects or as a basis for modeling. For example, you could use a collection of metas to form the initial shape of your model and then convert it to a mesh for further modeling or sculpting. Meta objects are also very efficient for ray tracing. .. warning:: Names of *Meta* objects are very important, as they define :ref:`families `, and only objects within a same family interact with each other. Unlike other object types, even edition (transformations) in Object Mode will affect the generated geometry within the edited families. Visualization ============= In Object Mode, the calculated mesh is shown, along with a black "selection ring". .. _fig-meta-ball-example: .. figure:: /images/modeling_metas_introduction_influence-selection.png :width: 450px Meta Ball in Edit mode. In Edit Mode (Fig. :ref:`fig-meta-ball-example`), a meta is displayed as a mesh (either shaded or as black wireframe, but without any vertex of course), with two colored circles: a red one for selection (pink when selected), and a green one for a direct control of the meta's stiffness (light green when active). Note that except for the :ref:`scale transformation `, having the green circle highlighted is equivalent to having the red one.