A terrain entry of type hill uses its shape field to define the tactical footprint of raised ground. Maps can author organic mounds, straight ridges, arcs, elbows, rings, traced paths, or exact painted cell masks.

The footprint feeds the same distance-field terrain logic used for crown height, slopes, rim walkability, entrance ramps, erosion, and line-of-fire blocking. Rendering operates on the resulting height map rather than on the authored shape type itself.

Available hill shapes

Accepted aliases are:

• boomerang, crescent, and horseshoe → arc;
• ridge and wall → corridor;
• crater → ring; and
• painted → mask.

path and mask cover footprints that do not fit the named primitives: a path traces a centerline, while a mask authors occupied cells directly.

Shape fields

width and depth

These define the overall footprint extents in the hill's local frame before rotation. A shape's centreline is inset by the ridge thickness, so a corridor with width: 40 and depth: 10 occupies an overall 40-by-10 footprint.

thickness

This controls the width of the raised band. It defaults to the short side for corridor and to roughly one third of the smaller extent for other banded shapes.

arc

The meaning depends on the shape:

• for arc, it is the sweep in degrees;
• for ring, it is the sweep and defaults to 360°; and
• for elbow, it is the angle between the two arms.

Defaults are 120° for arc, 360° for ring, and 90° for elbow.

arc_start

For an arc, arc_start defines where the sweep begins, measured in degrees from local +x. By default the sweep is centred on +x, so rotation alone can aim the feature.

taper

taper ranges from 0 to 1 and narrows an open shape toward both ends. A tapered arc forms a crescent.

points

points is used by path and defines a spine in map coordinates:

[
    { "x": 40, "z": 20 },
    { "x": 52, "z": 26 }
]

A path consults width and depth when thickness is absent, so it needs either an explicit thickness or suitable extents.

cells

cells is used by mask. Painted areas can be represented as row spans such as [z, x_from, x_to] or as individual [x, z] pairs. The map editor writes this representation directly.

rotation

rotation turns the complete shape around its x / z centre. It is ignored for mask, whose cells already exist in map space.

Example: a corner keep

The following hill creates a tapered 100° arc around a barracks and places both ramps on the protected side:

{
    "type": "hill",
    "shape": "arc",
    "x": 20,
    "z": 100,
    "width": 52,
    "depth": 52,
    "thickness": 8,
    "arc": 100,
    "arc_start": -95,
    "taper": 0.35,
    "height": 2.6,
    "entrances": [
        { "x": 22.4, "z": 86.2 },
        { "x": 33.8, "z": 97.6 }
    ]
}

The band wraps around the barracks at (20, 100) and faces the middle of the map. An attacker approaching from the centre meets raised ground, while the defender reaches it from the protected side. assets/maps/map_rivers.json contains this arrangement.

Map-editor authoring

Double-clicking a hill opens its JSON dialog. The projection panel shows occupied cells, and the layer controls switch between the hill body and entrance cells.

Painting the body stores the hill as shape: "mask" with the exact cells drawn. Runtime terrain raises those cells and slopes inward from their boundary, so the projection corresponds directly to the terrain footprint.

Leaving the body untouched preserves the authored shape and its numeric parameters.

The terrain toolbox also places Ridge, Boomerang, Elbow, and Ring presets with appropriate shape values and starting extents.

Flat features: terraces and raised ground

A terrain entry of type flat defines an absolute-height raised feature inside an ellipse.

Flat features do not use hill entrance rules or an unwalkable rim, so troops can approach them from any side. They are suitable for terraces, city shelves, raised forums, and broad traversable mountains.

taper

At taper: 0.20, the outer fifth of the radius forms the slope and the remaining area is plateau. The sacred mountain in map_aurelia_magna uses taper: 0.49, giving roughly half its radius to the climb.

A broad taper produces one continuous slope instead of the stepped profile created by stacked nested ellipses.

raise

Without raise, a flat feature sets the height of every covered cell, so overlapping features are order-dependent.

With "raise": true, a feature can only increase terrain height. A terrace and a mountain can therefore overlap by taking the higher value regardless of their order in the data.

{
    "type": "flat",
    "x": 0,
    "z": -306,
    "width": 300,
    "depth": 300,
    "height": 58,
    "taper": 0.49,
    "raise": true
}

Shaped hills define tactical barriers and ridges; flat features define traversable raised surfaces. Both are authored as terrain data and resolved into the same heightfield used by navigation and rendering.