MapPreviewGenerator

PMod Map Preview Generator

Generates real map preview thumbnails for Bopl Battle and exposes them to other mods through a small public API.

What it does

• Captures real in-game screenshots of every vanilla map (once per map, cached as PNG in BepInEx/plugins/PmodMapPreview)
• For BoplMapMaker custom maps: loads the map's biome scene, places the map on it and screenshots it — real thumbnails, not placeholders
• Installs the previews into the game's map selection UI automatically
• Re-generates a preview when a map is edited in the Map Maker
• Shows a progress panel at the top of the screen while previews are being generated

Matchmaking

This is a client-side mod: it only renders/creates preview thumbnails and never alters gameplay state. At load it increments the game's client-side-mod counter (CharacterSelectHandler_online.clientSideMods_..., via reflection), so matchmaking stays enabled — you can queue and play normally.

Reference the library

Two options:

Option A — compile-time reference (recommended)

Reference PMod.MapPreviewGenerator.dll from your project and add the dependency to your manifest.json:

"dependencies": ["BepInEx-BepInExPack_BoplBattle-5.4.2100", "PMod-MapPreviewGenerator-1.0.0"]

using PMod.MapPreviewGenerator;

Option B — runtime reflection (no compile-time dependency)

Resolve the type by name and call members via reflection. The type never causes a hard dependency, so your mod still works (without previews) if this one isn't installed.

static Type PreviewLib =

AppDomain.CurrentDomain.GetAssemblies().Select(a => a.GetType("PMod.MapPreviewGenerator.PreviewLibrary", false)).FirstOrDefault(t => t!= null);

The vote mod NextMapVote ships a working example of this pattern (PreviewLibAdapter.cs).

API reference

All members are public static on the class PMod.MapPreviewGenerator.PreviewLibrary.

Lifecycle overview

The generator is fully automatic: when you enter a menu scene (buildIndex | Fired whenever a real preview becomes available — vanilla mapId in vanilla mode, custom customIndex in MapMaker mode. Subscribe to refresh your UI. |

Vanilla maps

| Member | Type | Description |

|---|---|---|

| VanillaMapCount | int | Number of vanilla maps in the build. |

| HasRealPreview(mapId) | bool | True when a real (captured or cached) preview exists for the map. |

| EnsurePrepared(mapId) | void | Makes sure a preview exists for the map. Async: loads the PNG cache, otherwise queues a background capture and shows a procedural placeholder until it lands. Safe to call every frame. |

| TryGetSprite(mapId, out Sprite sprite) | bool | Fetches the current preview sprite, if any. Returns false (with sprite == null) when there is none yet. |

| InstallTexturePreview(mapId, tex) | void | Replaces the preview of a map with your own Texture2D. The generator tracks it for cleanup. |

| EnsureRealPreviewSync(mapId) | void | Synchronous variant of EnsurePrepared for vote-result time: guarantees the real cached screenshot even if its async load has not finished. Blocks briefly (one small PNG read). |

| StartPreloadAll() | void | Re-arms the menu preload and queues anything missing. Normally called automatically when a menu is entered. |

| QueueAllMissing() | void | Queues every map that still lacks a real preview. |

BoplMapMaker custom maps

| Member | Type | Description |

|---|---|---|

| CustomMapsAvailable | bool | True when the BoplMapMaker mod is present with loaded maps. |

| CustomMapCount | int | Number of custom maps available. |

| CustomMapName(customIndex) | string | Display name of a custom map (from its MetaData.json). |

| CustomMapType(customIndex) | string | Biome of a custom map: "grass", "snow" or "space". |

| CustomMapBaseLevelId(customIndex) | int | Vanilla base level id a custom map plays on (derived from its biome). |

| CustomMapJson(customIndex) | string | Raw.boplmap JSON of a custom map. |

| EnsureCustomPrepared(customIndex) | void | Same async semantics as EnsurePrepared, for custom maps. |

| Try