tree.cs

		void CollectTreeMeshes (Terrain terrain, List<RasterizationMesh> result) {
			TerrainData data = terrain.terrainData;

			for (int i = 0; i < data.treeInstances.Length; i++) {
				TreeInstance instance = data.treeInstances[i];
				TreePrototype prot = data.treePrototypes[instance.prototypeIndex];

				// Make sure that the tree prefab exists
				if (prot.prefab == null) {
					continue;
				}

				var treePosition = terrain.transform.position +  Vector3.Scale(instance.position, data.size);
				var scale = new Vector3(instance.widthScale, instance.heightScale, instance.widthScale);
				scale = Vector3.Scale(scale, prot.prefab.transform.localScale);

				bool colliderFound = false;

				void TreeCollider(Collider collider) {
					colliderFound = true;
					// The prefab has a collider, use that instead

					// Generate a mesh from the collider
					RasterizationMesh mesh = RasterizeCollider(collider, Matrix4x4.TRS(treePosition, Quaternion.identity, scale));

					// Make sure a valid mesh was generated
					if (mesh != null) {
						// The bounds are incorrectly based on collider.bounds.
						// It is incorrect because the collider is on the prefab, not on the tree instance
						// so we need to recalculate the bounds based on the actual vertex positions
						mesh.RecalculateBounds();
						result.Add(mesh);
					}
				}
				
				foreach (var collider in prot.prefab.GetComponents<Collider>()) {
					TreeCollider(collider);
				}
				
				foreach (var collider in prot.prefab.GetComponentsInChildren<Collider>()) {
					TreeCollider(collider);
				}
				
				if (colliderFound) {
					var instanceBounds = new Bounds(terrain.transform.position + Vector3.Scale(instance.position, data.size), new Vector3(instance.widthScale, instance.heightScale, instance.widthScale));

					Matrix4x4 matrix = Matrix4x4.TRS(treePosition, Quaternion.identity, scale*0.5f);

					var mesh = new RasterizationMesh(BoxColliderVerts, BoxColliderTris, instanceBounds, matrix);

					result.Add(mesh);
				}
			}
		}