GLTF - Infinite Track

Description

This example uses three glTF model assets from Kenney’s Toy Car Kit to build a small endless road scene. The car stays in place while the road segments move forward and loop behind it.

What You’ll Learn

• How to place multiple glTF model components in one collection
• How to loop repeated road segments to fake an infinite track

Setup

The collection contains three game objects: car, camera, and track.

car uses vehicle-racer.glb with the unlit material and the shared colormap.png texture.

camera is a perspective camera positioned so the car and road stay in view.

track contains six copies of track-road-wide-straight.glb and a gate.glb model. gltf.script moves the whole game object along the Z axis and wraps it back to the start once the last road section passes the camera.

The models use an unlit material so the texture colors stay clear and even without setting up lights. For the material and shaders details, see the Unlit material example.

How It Works

The script keeps a single Z position in self.current_z. Every frame it advances that value by self.speed * dt, then applies it to the track game object.

Once the track reaches the loop point, the script subtracts the loop length and starts again. That creates the illusion of a long road without needing to spawn or destroy any models.

Credits

The models used in this example are from Kenney’s Toy Car Kit, licensed under CC0.

Scripts

gltf.script

local TRACK_PART_COUNT = 6
local TRACK_PART_SIZE = 4

function init(self)
    self.current_z = 0 -- <1>
    self.loop_at_z = TRACK_PART_SIZE * (TRACK_PART_COUNT - 2) -- <2>
    self.speed = 5 -- <3>
end

function update(self, dt)
    self.current_z = self.current_z + self.speed * dt -- <4>
    if self.current_z > self.loop_at_z then -- <5>
        self.current_z = self.current_z - self.loop_at_z
    end
    go.set("/track", "position.z", self.current_z) -- <6>
end

--[[
1. Start the track at Z = 0.
2. Precompute the distance before the road should loop back.
3. Set the scrolling speed of the whole track.
4. Move the track forward every frame using delta time.
5. Wrap the track when it reaches the end of the visible road.
6. Apply the updated position to the `track` game object.
]]