Instancer Redesign

[TokisanGames]

Questions

What size of grid?

32x32
@ 1024 region size = 32x32 = 1024 cells
Min viewable 2 regions = 64m

User specified variable size?

Data stored at 32x32

Possible user option for generating larger chunks (eg. for lower lods @ longer distances) later

Share grid w/ collision, streaming?

Yes, possibly

Example Scale of Data

Live

• 9+ chunks around player (plus more with longer visibility)
• 64 mesh types: grass, rocks, debris, plants
• 2-4 lods for each mesh type, 1 visible, 1 shadow mesh
• 64*9 = 576 MMIs visible

Stored

• Each entry is Transform3D(4*vec3*4 = 48b) + Color(4*4 = 16b) = 64 bytes
• 1024cells * 64mesh * 1lod_buffer = 64k/region (4mb)
• Lods can share the same transform/color buffers in ram/vram.

Process

• MMs cannot change instance count at runtime, so must be recreated on every operation. Preallocation possible, but probably unnecessary.
• Change workflow to edit data storage, regenerate MMs and MMIs on every operation
• Transforms are stored scaled and local to region location offset; stored as if they were at (0,0)
• Store vertex_spacing in region that data is scaled by.
• When region is loaded, transforms scaled to current system vertex_spacing setting.
• Rescale transforms when set_vertex_spacing() run.
• Vertex spacing not applied to MMI nor to transforms during generation.

Data Storage

Terrain3DRegion

Current:

• Transforms are not scaled (spacing is currently broken) in global world space

_multimeshes {mesh_id:int} -> Multimesh

New:

• Vertex_spacing: float
• Transforms have vertex_spacing embedded, and in local region space

_instances { mesh_id:int } -> cell{v2i} -> [ TypedArray(Transform3D), PackedColorArray, modified ]

Terrain3DInstancer

Current:

_mmis { v3i(location.x, location.y, mesh_id:int) } -> MMI node

New:

_mmi_nodes { region_loc } -> mesh{ v2i(mesh_id, lod) } -> cell{v2i} -> mmi

Tree

Current:

• Terrain3D
  • MMIs
    • MMI nodes for all regions

New:

• Terrain3D
  • MMIs
    • region_container
      • MMI active nodes

Implementation Plan

• 1. Embed vertex_spacing in transforms, relative to local region.
  Add vertex_spacing to Terrain3DRegion.
  Only change vertex_spacing of transforms on load/set_vs().

• 2. Split MM data down to 32x32 storage
  append_location -> append_region -> append_cell -> storage in 32x32

• 3. Change MM/MMI generation off of new data structure

• 4. Add region container in tree / instancer

• 5. Support changing region size

• 6. Upgrade old data

Progress in #523

Plans for the Future

• Distance visibility per mesh type
• Lods
• Collision
• Streaming
• Larger chunk generation
• Sparse storage & density for grass
• And more Improve foliage instancing #43