Massing

The Massing mode

Massing is the fifth mode down the left rail of the iCity Editor, reached with Alt+5. It is where you pick a finished building and change it: its type, its storey count, or whether it exists at all. The status bar names the mode and its number as Massing (Alt 5) whenever nothing is selected.

The rail carries one tool in this mode, Draw Footprint, and D arms it. Everything else in the mode acts on a selection: click a building, and the card at the top of the panel names it and offers Delete Building plus the three type buttons, while the parameters column below shows Floors.

Massing does not create buildings on its own. Buildings rise out of lots, and lots come out of regions, so the controls that decide what gets built live one step upstream in Blocks mode. Massing mode is for the result.

Where buildings come from

Select a region in Blocks mode (Alt+3) and the parameters column under the selection card fills with one chain, read top down: Land Use, Massing Type, Subdivision Method, Setback Mode, Lot Settings, Building Height. The chain is drawn only while a region is actually picked, so if the column is empty, nothing is selected.

Land Use is the top of the chain and it decides how much of the rest exists. It is a row of four:

Land Use is not stored anywhere. It is a reading of two values that already exist — the region's content type and its massing type — so picking one writes both, and the row always shows something pressed.

Setback Mode is three values, and each one decides which setback fields Lot Settings then draws. Attached shares both side walls, so only Front and Rear have a free edge to measure from and the panel says “Attached: both sides are shared, so the side setback is zero.” Semi-Detached frees one side and adds a Side Setback field. Detached is free-standing, with Front, Rear and both sides.

Every one of those settings is sent to the region you picked, not to the city. The panel is showing that region's own values, and changing them here does not move the city default underneath. The split numbers each method reveals — minimum and maximum area, minimum width, irregularity, seed — are listed with their defaults on generation parameters, which is also where the general rule for what a parameter edit touches is written down.

Massing type

There are three massing types, and the interface calls them by two different sets of names. The region chain and the selected building's card use the descriptive set; the Draw Footprint picker uses the short set. They are the same three values underneath.

Two of them are conditional on the region. Mixed-Use Mid-Rise is offered only when the Subdivision Method is Footprint Map or the Setback Mode is Attached — and, above that, only under the Commercial land use. Pitched-Roof Low-Rise is not offered under Footprint Map at all, because a footprint map has no lot for a rowhouse to sit on. If a change to the Subdivision Method or the Setback Mode makes the current type invalid, it falls back to Flat-Roof Mid-Rise on its own. When the land use and the method leave nothing at all, the row is replaced by No massing type fits this Land Use with the current Subdivision Method. Change the method below.

To retype buildings that already exist, select them in Massing mode and press Flat-Roof Mid-Rise, Mixed-Use Mid-Rise or Pitched-Roof Low-Rise on the card. That is one edit for the whole selection: every selected building is re-massed together, and the choice is keyed on the owning block and the footprint anchor, so it survives a later re-split.

Floors, on one building

Select a building in Massing mode and a double-headed green arrow appears above its roof. Drag along the arrow to add or remove storeys — one floor per 3.5 m of drag, and never below one. The building rebuilds as you drag rather than on release, and the status bar reads the live count as Building: N Floors. Esc during the drag puts it back to the count it started at.

The same value is on the parameters column as a Floors field, which runs from 1 to 60. Type a number there when you know the one you want; use the arrow when you are judging it against the buildings around it.

A floor is 3.5 m. A Mixed-Use Mid-Rise spends 6 m on its ground floor and 3.5 m on every floor above it, so a five-floor Mixed-Use Mid-Rise is taller than a five-floor Flat-Roof Mid-Rise.

One building, or all of them

Floors and type do not have the same reach, and that catches people out. Floors is always the active building — the one you clicked last — however many are selected. Type is the whole selection in one edit. Anything city-wide is a region-level change, made upstream.

Because storey counts city-wide come from the type rather than from a number — the region's own Minimum and Maximum Floors are stored but not yet read by the engine — “fewer floors everywhere” is a Massing Type decision made on the regions, followed by per-building corrections with the arrow. What a parameter edit reaches when nothing is selected is covered on generation parameters.

Drawing a footprint by hand

Draw Footprint puts a building where the generator did not: the polygon you draw is the footprint, extruded straight up with its walls exactly on the outline and no setback. It snaps to sidewalk bounds, block outlines and lot outlines, and it will also sit on its own with nothing under it.

1. In Massing mode, press D or click Draw Footprint on the rail.
2. With nothing selected, the parameters column shows the two settings the next footprint will be drawn with: Type and Height. Set them before you draw — Height starts at 9 m and accepts 3 m to 200 m.

   massing-footprint-defaults.png

   Massing mode with nothing selected and the Draw Footprint tool armed on the rail. The parameters column must show the Type row (Residential / Mixed Use / Terraced) and the Height field reading 9 m.

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3. Click corners in the viewport. The strip reads Draw Footprint: N Points, and a ghost of the volume is drawn at the Height as you go.
4. Hover the first corner — the caption changes to Close Shape — and click, or press Enter to confirm. Enter with fewer than three points builds nothing.
5. Esc mid-stroke cancels it and builds nothing. With the tool armed and no points down, Esc or a second D puts the tool away.

The type picker is a hold, not a click. Press and hold the Draw Footprint rail button for about half a second and a chooser opens with Residential, Mixed Use and Terraced; a short click only arms or disarms the tool. The hold arms the tool too, so picking a type leaves you ready to draw. Its footer line says the height is in the tool header — it is not, it is in the parameters column described above.

A drawn footprint is a building like any other afterwards: it can be selected, retyped and given a different floor count. Buildings that arrive from a lot you drew or loop-cut are a different matter — that path carries no height, so they start at about three storeys and you set the count yourself.

When the handles are not there

Massing edits are the first thing to stop working on a building marked UNSYNCED in the selection header: a locked building gets no floors arrow and no procedural editing, which is explained on selecting and editing.

Three other things silence the mode, and none of them is a fault:

• —The engine is stopped. Every mode except Graph shows The iCity engine is not running. Start it to edit your city. with a Start button under it. Your city lives in that engine process rather than in your .blend — see the engine.
• —Blender's Move, Rotate or Scale tool is active in Blender's own toolbar. The floors arrow hides with the other drag handles until you go back to Blender's Select tool.
• —There is no eligible building under the pointer. Where a Floors control would be, the interface says Floors: procedural buildings only.

Deleting is permanent. Delete Building on the card, or Del / X on the selection, removes the building and a regenerate does not bring it back. Ctrl+Z rewinds the engine's own city one step, which is not the same as Blender's undo.