terrain

Ground, as procedural operations. terrain.source opens a rect of ground as a tiled Raster with a height layer; every other op in the family takes that Raster, changes it, and hands it on — so a valley, a mountain range, an island and a coastline are all the same graph with different nodes in it. terrain.write carries the result back out — into a .terrainData that a Terrain component stands an entity on.

Every op is an ordinary procgen op, so any graph can reach them and they compose with the rest of the registry: the shaping ops take a Raster and hand one on, and the ops that stand things on the ground hand back points.

Ops

The ground

• terrain.source — the rect a terrain graph starts from: a tiled raster with a height layer, at a chosen resolution.

Shapes and noise

• terrain.fbm — fractal noise over the height layer; ridged or plain.
• terrain.flatten — level the ground inside a placed shape.
• terrain.cone — a cone or crater at a placed centre.
• terrain.ridge — a raised or cut ridge along a placed line.
• terrain.ramp — a graded slope between two heights.
• terrain.terrace — quantize height into steps.

Rules and blending

• terrain.mask — write a soft band over one feature (height, slope, or distance to a curve) into a named layer.
• terrain.project — band height by distance to a curve.
• terrain.layer — blend a painted layer into height.
• terrain.stamp — blend a texture into height at a placement.
• terrain.coast — pull the ground outside a landmass down to the shore.

Water

• terrain.lake — fill a basin to a water level.
• terrain.river — carve and fill a channel along a curve.
• terrain.sea — flood everything below a level.

Erosion

• terrain.erode — hydraulic (droplet) or thermal erosion, batched over the raster's tiles.

Standing things on it

• terrain.scatter — points across the surface, weighted by a mask layer and banded by slope and height, each carrying the normal and slope under it.
• terrain.drape — anyone else's points put down onto the ground: a graph's own raster, or the scene's ground.
• terrain.ground — the ground the scene's Terrain entities stand on, as a graph value read afresh every frame. Wired into terrain.drape, points land on it wherever the graph stands, each marked grounded, and a Generator sets them again when the ground is rebuilt or the Generator moves.

Out of the graph

• terrain.write — the whole landscape as a .terrainData: the heightfield (rgba32f, R metres, G/B gradient), the control textures saying which surface covers where (rgba8, four layers a texture, weights normalized to sum to one), the holes mask, and the table of what those surfaces are.
• terrain.to_texture — ONE layer as a Texture on its own, for a raster feeding something other than a landscape.
• terrain.from_texture — the way back in, and how ground made anywhere else becomes something these ops can carve.

local ref = g.op.terrain.write({ raster = ground, name = "dunes", layers = { "sand", "rock" } })

Then a Terrain component standing on that landscape is what puts it in a scene.