Regions & compartments

A region is an area cut into one slab: a chamber, a reservoir, a well, a mixing cavity. It has no route and no ends, and a channel reaches it by landing on its wall.

Compartments

A region is divided into compartments, and the compartment is what you select, name and edit. A newly drawn region holds one compartment, which is the region itself. Divide the region and each piece gets a row of its own.

A compartment is filled with either void or material:

• A void compartment is a pocket: the slab is carved away there and the fluid is in it. A pocket carries its own depth, wall profile and corner radii, so one region can hold a shallow antechamber beside a deep well, or a step in a chamber’s floor.
• A material compartment is a hole: the slab is left untouched there and the fluid is not in it. Use one for a post standing in a chamber, an island, or a wall between two halves of one shape.

Switching a compartment’s fill turns one into the other. A pocket switched to material becomes a hole and the slab closes over it; a hole switched back is carved out again. Material inside material is not a state the slab can hold, so that direction is refused. See Inspector for the fill control.

Nested shapes

Drawing inside a compartment produces its opposite. Inside a chamber you draw a hole, an island of slab standing in the void. Inside that hole you draw a pocket, a void carved into the island. You can go on nesting as deep as you need.

A pocket drawn inside a pocket is not separated from it. The two meet along their shared boundary and form one void that differs only in depth, so separating a void from the void around it takes a hole between them.

The weld

Welding joins the shape you are drawing to one that is already there: place a vertex on an existing wall and the two shapes share that boundary exactly, with no material between them. Two shapes drawn separately land their vertices a fraction apart, leaving a thin wall you did not ask for.

A welded shape can take a run of the wall it welds to along with the boundary, which is how a corridor comes off a chamber. See Toolbar & tools for the clicks that decide how much of the wall comes along.

Seams and movement

A seam is the boundary two welded compartments share, and the app draws it as a hairline. It is the one part of a compartment’s outline that fluid crosses.

Welding also merges the shapes into one movable unit, so dragging a welded compartment brings its neighbours with it. A shape set inside another, such as a hole in a chamber or a pocket in a hole, is not welded to it and moves on its own.

Welding onto a region that is a separate child absorbs it: its shape joins the one you drew, and it stops being a child of its own. Absorbing is refused where it would discard something you authored, such as a position bound to an expression or a label a pin sources, and the chip says which.

Compartment removal

Deleting a compartment removes that piece of a divided region, and the whole shape where the region holds one compartment. It is refused while a channel lands on that compartment’s wall, since the landing would have to move to a wall you did not choose.

Deleting a piece is also how you put a wall across the top level of a region, where a hole cannot go. Carve a chamber into three pieces, all of them pockets, and delete the middle one: the slab closes over it and leaves the two ends separated. One tier down, inside a pocket, that wall can be a hole with a row of its own instead.

Compartment names

A compartment with no name of its own shows a derived one: region for the compartment that is the region, and hole 1, pocket 2, hole 3 numbered among its siblings. Those numbers are positional, so removing a sibling renumbers the rest. Name a compartment where you need the label to stay put.

Placement

The outermost compartment carries the region’s own pos, rot and layer, so moving the region moves everything inside it. A nested compartment carries dx, dy and rot instead, which move it within the shape that contains it. A nested compartment has no layer row, since everything in one region is cut into one slab.

Regions in the network

Channels reach a region only through wall-bound points. A region with none on it is a cavity in the slab that nothing flows into.

See also

• Channels & points — wall-bound points and how a channel breaks into a wall.
• Inspector — the fill control, the compartment detail and the Body tree.
• Layers, stacks & processes — the slab a region is cut into.
• Fabrication overrides — the depth, walls and corner radii a pocket carries.
• Toolbar & tools — the Draw region gesture, and the wall clicks a weld is made with.
• Keyboard & mouse reference — the Draw region tool’s keys.