2. Building the meshes

Maya and Blender both work. The task is identical in either: take the area of a zone, cut it into a grid, and end up with one separate mesh object per cell.

The critical word is separate. One mesh with the grid drawn on it as faces is a single object with single bounds — the mod cannot tell depth 1 from depth 3 inside it. Each cell must be its own object.

What each cell needs to be

• Its own object, not a face group or a submesh
• Convex-ish and roughly box-shaped — bounds are what’s tested
• Tall enough that a car body passes through it, not just skims the top
• Overlapping its neighbours slightly, or at least sharing an edge with no gap

Height matters more than people expect. Detection tests points against the mesh’s bounds. If your cells are flat planes, a car pitched under braking can pass over one without registering. Extrude them into slabs — roughly car height is a safe default, taller does no harm.

Gaps are worse than overlaps. A car crossing a seam between two cells should always be inside one of them. Overlap by a few centimetres.

Maya

Building the grid

1. Model the zone footprint as a single flat polygon following the track edge.
2. Extrude it upward to about car height.
3. Cut it into the grid with Mesh Tools → Multi-Cut, or model one cell and duplicate it along the two axes.
4. Mesh → Separate to break the result into individual objects.

Multi-Cut on a curved zone is usually easier than duplicating, because the cells need to follow the track’s curve rather than a straight grid.

Naming

Maya’s naming rules are friendlier than the contract needs, so you can name objects to their final form directly:

zone_1_1_1, zone_1_1_2, zone_1_1_3
zone_1_2_1, zone_1_2_2, zone_1_2_3

If you’d rather rename in Unity with the SDK inspector, name them anything predictable here — z1_L1_D1 — and fix them up after import. Both work; naming in Maya means the mesh is correct the moment it lands.

Beware Maya’s auto-renaming on duplicate: zone_1_1_1 duplicated becomes zone_1_1_2 on its own, which happens to be the right pattern going one way and completely wrong going the other. Check the outliner before exporting.

Pivots

Freeze transforms (Modify → Freeze Transformations) and delete history before export. A cell with a baked-in scale or rotation offset can produce bounds that don’t match what you see.

Centre each pivot on its cell (Modify → Center Pivot). Not strictly required — bounds are world-space — but it makes the Unity scene far easier to work with.

Export

FBX, with:

• Smoothing groups off (irrelevant, these are invisible)
• Triangulate on
• Units: centimetres — Maya default is centimetres and Unity expects a 1 unit = 1 metre result. If your track imports at the wrong scale, this is where it went wrong.

Blender

Building the grid

1. Model the zone footprint as a plane following the track edge.
2. Extrude up to about car height.
3. Cut the grid with loop cuts (Ctrl+R) — one set along the length, one set across the depth.
4. P → By Loose Parts after separating faces, or select each cell’s faces and P → Selection.

For a curved zone, the cleanest approach is often to model one cell, then use an Array modifier along a Curve following the track edge for the length steps, and a second array for depth. Apply the modifiers, then separate by loose parts.

Naming

Blender’s outliner names become the object names on export. Name them to the contract:

zone_1_1_1
zone_1_1_2
...

Blender appends .001, .002 to duplicate names, and that suffix survives FBX export — zone_1_1_1.001 does not match the contract and will not be scored. This is the single most common way a Blender-authored zone silently fails.

After separating by loose parts, rename every object explicitly. Batch Rename (F2 with multiple selected) handles it, or use a short script:

import bpy
# Name the selected cells in selection order: zone_{ZID}_{L}_{D}
ZID, DEPTHS = 1, 3
for i, ob in enumerate(bpy.context.selected_objects):
    length = i // DEPTHS + 1
    depth  = i %  DEPTHS + 1
    ob.name = f"zone_{ZID}_{length}_{depth}"

Selection order is not guaranteed to be the order you clicked, so sort or verify in the outliner before trusting it.

Transforms

Ctrl+A → All Transforms on every cell before export. An unapplied scale is the Blender equivalent of Maya’s unfrozen transform and causes the same bounds mismatch.

Export

FBX, with:

• Apply Transform ticked
• Forward: -Z, Up: Y — Blender is Z-up, Unity is Y-up. Getting this wrong lays your zones on their side, which is hard to spot when they’re invisible.
• Limit to: Selected Objects if your scene has the whole track in it

Materials

Zone meshes must not be visible in game.

Give them all one shared transparent material, or a material you’ll disable the renderer on later. Do not delete the MeshRenderer — the mod finds zones by renderer bounds, so a mesh with no renderer is invisible to CHAPPiE too.

A fully transparent material is the safest option: renderer present, nothing drawn.

Before you export

• Every cell is a separate object
• Names match the contract exactly, no .001 suffixes
• Transforms frozen / applied
• Cells are slabs, not planes
• No gaps between neighbouring cells
• Overshoot strips modelled beyond the deepest band
• Material is transparent, renderer intact

Next: 3. Unity setup