Get Point on Decalroad (Flowgraph Node)

Overview

• Node Name: Get Point on Decalroad
• Category: repeat_instant
• File: extensions/flowgraph/nodes/scene/getPointOnDecalroad.lua

Returns the position and approximate forward rotation of a specific control point on a DecalRoad object.

Pin Schema

Input Pins

Output Pins

Behavior

• _executionStarted() - Resets cached road object and index.
• work() - Each frame:
  1. If roadId changed, looks up the road via scenetree.findObjectById(), caches it, reads node count and looped status.
  2. If idx changed and is within bounds (0 to nodeCount-1):
     • Gets the node position via roadObj:getNodePosition(idx).
     • Computes an approximate forward direction by getting prev and next nodes (wrapping for looped roads).
     • Builds a quaternion from the forward direction using quatFromDir(forward, up).
  3. Caches results to avoid redundant lookups.

Internals

• self.roadObj - Cached DecalRoad scene object
• self.oldRoadId / self.oldIdx - Change detection for caching
• self.maxIdx - Maximum valid node index
• self.looped - Whether the road loops (from the looped field)

Key Dependencies

• scenetree.findObjectById(id) - Finds the road object
• roadObj:getNodeCount() - Number of control points
• roadObj:getNodePosition(idx) - Position of a control point
• roadObj:getField("looped", 0) - Whether the road is looped
• quatFromDir(forward, up) - Quaternion from direction vector

How It Works

The node provides access to DecalRoad control points - useful for placing objects along roads, creating waypoint sequences, or aligning cameras with road direction. The rotation is approximated by computing the direction between the previous and next control points, giving a tangent-like orientation. Looped roads wrap indices correctly.

Example Usage

-- Iterate through road points to place markers
-- Wire roadId from an ID by Name node targeting a DecalRoad
-- Increment idx over time to animate something along the road
-- Use rot output to orient objects facing along the road

Additional Methods

C:init()

Initializes the node, setting up pins and default properties.

See Also

• Collection Marker (Flowgraph Node) - Related reference
• Custom Lua Command (Flowgraph Node) - Related reference
• Get Object Field (Flowgraph Node) - Related reference
• FlowGraph Guide - Guide