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| -rw-r--r-- | doc/testplans/terrain_loading.md | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/doc/testplans/terrain_loading.md b/doc/testplans/terrain_loading.md index b84daf6f73..d8be930b33 100644 --- a/doc/testplans/terrain_loading.md +++ b/doc/testplans/terrain_loading.md @@ -1,4 +1,29 @@ -- Texture terrain should load -- PBR terrain should load if enabled +# Terrain Loading + +## Behavior overview + +- Texture terrain should load if applied +- PBR terrain should load if applied, even if the feature flag is disabled - Related subsystem: A change to the PBR terrain loading system may affect the texture terrain loading system and vice-versa -- Related subsystem: Minimaps should load if terrain loads (may take longer) +- Related subsystem: Minimap should load if terrain loads + - They may not finish loading at the same time + +## Implementation details + +This section is provided mainly for clarification of how the terrain loading system works. + +The simulator sends 4 terrain composition UUIDs to the viewer for the region. The viewer does not know ahead-of-time if the terrain composition uses textures or materials. Therefore, to expedite terrain loading, the viewer makes up to 8 "top-level" asset requests simultaneously: + +- Up to 4 texture asset requests, one for each UUID +- Up to 4 material asset requests, one for each UUID + +It is therefore expected that half of these asset lookups will fail. + +The viewer inspects the load success of these top-level assets to make the binary decision of whether to render all 4 texture assets or all 4 material assets. This determines the choice of composition for terrain both in-world and on the minimap. + +The minimap also attempts to wait for textures to partially load before it can render a tile for a given region: + +- When rendering texture terrain, the minimap attempts to wait for top-level texture assets to partially load +- When rendering PBR material terrain, the minimap attempts to wait for any base color/emissive textures in the materials to partially load, if they are present + +We don't make guarantees that the minimap tile will render for the region if any aforementioned required textures/materials fail to sufficiently load. However, the minimap may make a best-effort attempt to render the region by ignoring or replacing data. |