3. Unity setup

Import the meshes, attach the SDK, place the run-control geometry.

Install the SDK

Copy the UDSM_SDK/ folder into your track project at Assets/UDSM_SDK/. The components appear under Add Component → UDSM/….

These are editor-only helpers. They rename their GameObject in OnValidate and do nothing at runtime — they’re stripped when CarX loads the map, which is expected.

Import the zone meshes

Drag the FBX in. Check three things before going further:

Scale. Put a known-size object next to a zone cell. If your cells are 10× or 0.01× what you modelled, fix the FBX import scale factor rather than scaling in the scene — a scaled transform can produce bounds that don’t match the visible mesh.

Orientation. Zones should be standing up, covering the track surface. If they’re lying on their side, your Blender export axes were wrong.

Names survived. Check the hierarchy for .001 suffixes or Unity’s own deduplication. Fix now, before you attach anything.

Attach UDSMDriftZoneSegment

Select a zone cell → Add Component → UDSM → UDSM Drift Zone Segment.

Set:

The GameObject renames itself the moment you change a field. The scene view draws a wire mesh coloured by depth: blue → cyan → yellow → red as depth increases.

That gizmo is the main reason to use the SDK. Scrub the camera over a finished zone and the colour ramp should march cleanly from track side to wall. A cell that’s the wrong colour has the wrong depth index, and you can see it without reading a single name.

Detection types

You can mix types within a zone. A common pattern is Bumper for the main bands and InnerClip for a tight apex.

Doing it faster

Select a whole row of cells at the same depth and add the component to all of them at once, then set ZoneID and DepthIndex on the multi-selection. Only LengthIndex differs per cell, so you’re editing one field each.

Angle windows

For a zone that needs a specific angle range, create an empty GameObject, add UDSM Drift Zone Angle Range, set ZoneID, Min and Max.

Put it on its own object. If you add it to a zone mesh, both components rename the GameObject and the last one to run wins — you’ll lose either the zone cell or the marker.

Special lines

Add Component → UDSM → UDSM Special Line Marker on a mesh, then pick the type.

run_start_line

The one with a geometry requirement: use a BoxCollider, not a mesh collider.

The mod does an oriented-bounding-box test, so the box can be rotated to follow the track. Size it to hold a stationary car comfortably — all four wheels must be inside it and the car must be stopped for the countdown to start. Too tight and drivers can’t arm it; too loose and it arms in the run-off.

run_finish_line, initiation_line

Convex MeshCollider with isTrigger = true. Make them wide enough to span the whole track — a driver taking an unusual line must still cross them.

initiation_line is a DQ trigger: crossing it without having initiated a drift zeroes the run. Place it where you genuinely expect drivers to already be sideways, not at the entry to the approach road.

Brake zones

brake_zone_start_{N} / brake_zone_end_{N} in pairs. These only flash a HUD notice — no scoring effect on their own.

Start lights

Attach UDSM Start Lights Controller to the root of your lamp post. The root renames to start_lights.

Drag the four panel MeshRenderers into the array top to bottom. They rename to panel_1 … panel_4.

Then, for each panel:

1. Give it its own material instance. Duplicate the material in the Project window — if all four share one material, all four light together and the countdown is meaningless.
2. Enable Emission on the material.
3. Confirm the _EMISSION keyword is ticked. Unity strips emission from a build if it was never enabled in the editor, and the runtime write then does nothing.

The mod drives _EmissionColor directly. If panels stay dark in game, it’s nearly always one of those three.

HDRP scenes usually need the emission intensity raised — that’s StartLightsEmissionIntensity in the player’s config.json, default 15.

Walls and off-track

Neither needs marking. See naming contract for why.

Wall contact comes from CarX’s own collision events, so any solid barrier already registers taps and impact DQs.

Off-course reads CarX’s per-wheel surface type and counts anything that isn’t asphalt. Check your run-off areas are not authored as asphalt, or the off-course DQ won’t fire there. This is worth testing explicitly.

Before exporting

• Every zone cell has the component and correct indices
• Depth colours ramp cleanly track-side → wall in the scene view
• Overshoot strips placed past the deepest band
• run_start_line has a BoxCollider sized for a stopped car
• run_finish_line and initiation_line span the full track width
• Start light panels each have their own emissive material
• Zone materials are transparent and renderers are enabled
• Run-off surfaces are not asphalt

Next: 4. Export and test