# Full-map symmetry

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English | [French version](MapSymmetry.fr.md)
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**Full Map Symmetry** (`MapDefinition.FullMapSymetry`) is **false by default**.
Find it beside **Symmetry** in **Simple > Players and strategy** or
**Expert > Map, players and biome**.

When disabled, the original generator is used: **Symmetry** controls player-start
placement, while terrain, rivers, mountains, paths, forests and decoration retain
their natural layout. The requested start count is not rounded up to complete
symmetry groups. Select **None** for free player-start placement as well.

When enabled in procedural generation, **Symmetry** applies to terrain and water, mountains,
plateaus and ramps, roads, forest patches, resources, strategic zones and prop
placement. Corresponding terrain surfaces and their mesh colliders use the same
geometry, including contour smoothing and vertex noise.

| Mode | Relationship | Start group size |
| --- | --- | --- |
| None | Free generation | 1 |
| Horizontal | Reflect across the horizontal centre line | 2 |
| Vertical | Reflect across the vertical centre line | 2 |
| Diagonal | Exchange the two map axes | 2 |
| Rotational | Turn 180 degrees around the map centre | 2 |
| Quadrant | Reflect across both centre lines | 4 |

With **Full Map Symmetry** enabled, choose the mode in **Map, players and biome**. The Inspector displays the number
of generated start locations. When the requested player/base count does not fill
complete groups, the generator adds empty start locations while keeping the
selected symmetry. For example, three players with Quadrant produce four starts;
five players produce eight. The Player Count and Additional Main Bases settings
are not rewritten.

`MapDefinition.ResolvePlayerStartCount()` predicts this total. The generated
`MainBaseCells` and `PlayerSpawnWorldPositions` lists include the extra locations;
the game can leave them unused. All start locations receive the corresponding
terrain, expansions and resources.

Player expansions follow the same transformation as their base. Neutral zones
are completed in symmetric groups, so a requested count can be rounded up.
Rivers and mountain features are repeated as complete features to preserve their
continuity across symmetry boundaries. Roads and protected passages retain their
corresponding accesses; generated bridges keep water below their decks.

Altitude is also symmetric. The generated altitude field, or the samples of a
custom heightmap, are combined across the selected symmetry. The source texture
is not edited. Standing water stays level and river altitude constraints remain
active.

Prop instances reuse the same prefab variant, scale and matching orientation at
corresponding locations. Prefab art and materials remain shared. Pack Content
retains these instances and their collider settings, and GPU instancing remains
available. Shader lighting, wind and texture variation continue to animate
normally; symmetry describes the map layout and terrain geometry.

Imported image maps keep their authored layout regardless of this switch.
Existing recipes without `FullMapSymetry` use its default value, false. Enable it
explicitly to retain complete symmetry when regenerating those recipes.
Regenerate after changing the switch or mode; an existing mesh is not modified
by changing the setting alone. The setting is saved with generation recipes.