Rectangle Generator

Generates a planar graph of nodes by recursively subdividing rectangles, used by procTrack for gymkhana track generation.

Overview

util_rectangleGen is a helper module (not an extension - it uses require) that takes a set of starting rectangles and parameters, recursively subdivides them, and returns a graph with nodes at rectangle centers and neighbor adjacency information.

Module path: lua/ge/extensions/util/rectangleGen.lua

Exports (M)

Internals

Graph Structure

graph = {
  nodes = {
    { x, y, neighbours = {{index, dist},...}, name, closestNeighbourDist, force },
    ...
  },
  start = node_or_nil,  -- node with start flag
  finish = node_or_nil  -- node with finish flag
}

Subdivision Algorithm

1. Copies startingRects (excluding noSplit rects) into a working list.
2. Iteratively picks the largest rectangle and splits it vertically or horizontally:
   • Direction chosen by params.rectModeParams.vertSplitFunction(width, height).
   • Split position chosen by params.rectModeParams.cutValueFunction(), clamped to respect minXDist/minYDist.
3. Stops when rectangle count reaches params.rectModeParams.numNodes or no more splits possible.
4. noSplit rectangles are appended afterwards (fixed nodes with optional start/finish flags).

Neighbor Detection

Two rectangles are neighbors if they share an edge (within floating-point tolerance 0.001):

• Left/right adjacency: matching X boundary and overlapping Y range.
• Top/bottom adjacency: matching Y boundary and overlapping X range.

Node Placement

Each rectangle's center becomes a node. The closestNeighbourDist field records the minimum distance to any neighbor, used by procTrack for radius calculations.

How It Works

1. procTrack.checkParams() calls require('util/rectangleGen').
2. makeBaseNodePositions() calls getGraph(params).
3. The returned graph feeds into the Hamiltonian path solver.

Lua Examples

-- Used internally by procTrack, not typically called directly
local rectGen = require('util/rectangleGen')
local graph = rectGen.getGraph(params)
-- graph.nodes contains positioned nodes with neighbor info

Additional Exports

• M.dist - (undocumented)
• M.getGraph - (undocumented)

See Also

• Auto Annotation - Related reference
• Booster - Related reference
• Calibrate ESC - Related reference
• Game Engine Overview - Guide