Adding 3D Models to Decentraland Scenes

RULE: Check bounding boxes before placing models

A model's Transform.position is its local origin, not its visual extent. Vegetation and large structural models often extend 6-12 m beyond their origin. A tree placed at x=2 can render at x=-10 — outside scene bounds and invisible.

Before placing any GLB model, determine its actual world-space bounding box. Raw accessor min/max values are NOT sufficient — many models have large node-level scales baked in. You must account for node transforms. Use the bounding box script in {baseDir}/references/model-patterns.md.

Then compute the safe placement zone: safeMinX = -bbox.minX + edgeMargin (>=1m) etc. Place the origin only within the safe zone. When bounding box is unknown, use a conservative 12 m buffer from all edges for trees/large foliage, or 3 m for small props.

RULE: Account for model depth before neighboring entities

Two models don't overlap just because their origins are different. Always verify that origin +/- extent doesn't intersect any neighbor's bounding box. Pay special attention to deep arch/gateway models (can extend 14 m in +/-Z) and rotated models (rotating 90deg around Y swaps X and Z extents).

RULE: Single-sided models — orient the rendered face toward players

Many GLB models use back-face culling. The rendered face is typically toward local -Z. Y rotation transforms facing: 0deg -> south, 90deg -> east, 180deg -> north, 270deg -> west. When players approach from both sides, add a second copy rotated 180deg. Prefer double-sided geometry for elements visible from all angles.

Decentraland uses a Y-up coordinate system — test model orientation after import: a model exported Z-up (common from Blender) loads tipped over and must be re-exported with "Y Up".