Orrery Terrain · OrreryTerrain module · struct

FTerrainChunkPosts

The heights of one chunk, read once from a published snapshot and shared, immutable, by everything downstream of the ground: the chunk's collision field and its render chunk.

Declaration

struct FTerrainChunkPosts

Header: #include "TerrainChunkPosts.h"
Module: PublicDependencyModuleNames.Add("OrreryTerrain"); in your module’s Build.cs.
Stability: Stable: changes within a major version only add.
Thread: Built on a task-system worker from an FGroundQuery the game thread acquired; read on any thread afterwards.

Description

A chunk is one edit-layer tile (OrreryTerrain::Native::kTilePosts² posts, edge posts duplicated with the neighbours). Positions are relative to Origin, so a chunk far from the world origin keeps full XY precision (LWC: the doubles live in Origin only).

Heights are whole millimetres of the edited ground, stored as 16-bit steps above the lowest post of their block of 8 × 8 posts; a block whose own relief passes 65.535 m keeps the steps' high 16 bits too: lossless either way. The reads answer float cm, float(double(Mm) * 0.1), which keeps every millimetre apart below ±10.48 km.

⚑ Origin.XY is fixed per tile. Origin.Z, the datum of the heights, is 0 today; a consumer must still add it, and must not assume it stays the same between two revisions of a chunk.

Tier 3 data, plain C++, no UObject: GC-invisible, passed by TSharedRef<const ...>. Built on a task-system worker from an FGroundQuery the game thread acquired; read on any thread afterwards.

Functions

IsEmpty
HeightAt
One post's height, cm above Origin.Z.
CopyHeights
Copy every post's height, cm above Origin.Z: Posts² values, row-major (index = Row * Posts + Col, the Chaos layout).
HasCellClass
Whether some cell has a ground class other than 0; false means every cell is class 0.
CellClassAt
One cell's ground class: the value of Channels::GroundClass at the cell's (0,0) post.
IsPainted
Whether some post holds paint: a layer other than 0, or more than one pair.
PaintAt
One post's paint: its canonical pairs, heaviest first, absolute weights summing to 255 (slot 0's included), as a point query (FGroundQuery::Paint) answers.
CopyPaint
Copy the paint as lists, Stride pairs per post, post-major: post K's pair S at K * Stride + S, posts row-major like the heights (FGroundQuery::CopyEditTilePaint's layout at Stride kPaintSlots).
GetAllocatedSize
Bytes these posts own: the struct (which holds a tile's block bases, 4 bytes a block), the heights (2 bytes a post; a block of more than 65.535 m of relief adds 2 bytes a post, and then the block table 2 bytes a block), the ground classes and the paint planes made for them alone (FPaintPlaneRefs::OwnedMask).
Readstatic
Read one edit-layer tile from a snapshot: heights (Modified surface) and ground class.

Properties

Name	Type	Default	Meaning
`Tile`	`FIntPoint`	`FIntPoint::ZeroValue`	Edit-layer tile this chunk covers.
`Origin`	`FVector`	`FVector::ZeroVector`	World XY of post (0,0), cm; Z is the datum of the heights (0 today).
`Cell`	`double`	`100.0`	Post spacing, cm.
`Posts`	`int32`	`0`	Posts per side; 0 = empty.
`PaintSlots`	`int32`	`0`	Most (layer, weight) pairs any post of the chunk uses, 1..kPaintSlots; 0 when every post is unpainted (layer 0 alone). A consumer that draws fewer pairs reads the leading ones, the heaviest.
`MinHeight`	`float`	`0.f`	Bounds of the heights, cm above Origin.Z.
`MaxHeight`	`float`	`0.f`	—
`Revision`	`uint64`	`0`	Snapshot revision the heights were read from.
`bApproximate`	`bool`	`false`	At least one post answered from the mip pyramid, or the class or paint is Pending (a cold plane whose page has not landed: they read the defaults). Either way the ground journal reports the tile again when the exact data lands.