Terrain

Jackdaw’s terrain is a heightmap-backed mesh, chunked for streaming and edited with brush-style sculpt tools. The crate that does the work is jackdaw_terrain; if you want the actual data structures, the entry points are Heightmap, apply_brush, and build_chunk_mesh_data.

Add a terrain

Add > Terrain in the hierarchy. You get a flat heightmap component on a new entity, with a chunked mesh underneath. Resolution and physical size are properties on the Terrain component, editable in the inspector.

Sculpt

Select the terrain, then pick a sculpt tool from the toolbar or the terrain panel. Available tools:

• Raise / lower. Add or subtract height under the cursor.
• Flatten. Drag heights toward the height under the click point.
• Smooth. Average heights inside the brush radius.
• Noise. Add procedural noise inside the brush radius; good for breaking up flat areas without sculpting by hand.

Brush radius and strength sit in the toolbar. The brush preview ring tracks the cursor so you can aim before committing.

Ctrl+Z undoes the last stroke. Each contiguous drag is one undo entry, not one entry per heightmap sample.

Erosion

The erosion pass simulates hydraulic erosion across the whole heightmap. Adjust iteration count, evaporation rate, and sediment capacity in the panel; click Run. It is a one-shot operation, not a real-time tool.

This is the slowest thing in the terrain workflow, since it runs on the CPU and rebuilds every chunk mesh when it finishes. Save before you click. We do not have a cancel button yet.

Texture painting

Texture painting on terrain is on the roadmap but not built. Today the terrain takes a single material applied to the whole surface. If you need varied surface textures, blend in your fragment shader or split the heightmap into multiple terrains, each with its own material.

Chunking

Chunks are 32 cells per edge (src/terrain/mod.rs::CHUNK_SIZE). Edits only rebuild the chunks that overlap the brush, which is what keeps sculpting fast on large heightmaps. There is no LOD or frustum streaming yet; every chunk renders at full resolution.

Common gotchas

• Mesh shows seams between chunks. Normals are computed per chunk. The boundary samples should match across chunks; if they don’t, an edit straddled the boundary and one side never rebuilt. Touch both sides with the smooth tool to force the rebuild.
• Erosion result looks wrong. Iteration count is the knob to tune first. Defaults aim for a generic mountain; rolling hills want fewer iterations and a higher evaporation rate.
• Standalone game shows no terrain. jackdaw_runtime doesn’t pull in jackdaw_terrain. If your game needs terrain at runtime, add jackdaw_terrain to your standalone Cargo.toml and bring whatever plugin / systems you want into your game’s plugin alongside JackdawPlugin.