Brighterscript Game Engine

SolidWorld

A set of static, axis-aligned solid rectangles for top-down movement (walls, water, prop bases), and moveAndSlide() to move a box through them: it stops flush against solids, slides along walls, and eases around corners it only just clips.

Every rectangle is {x, y, w, h} - (x, y) is the bottom-left corner, world +y up. This is plain rectangle maths, separate from colliders: colliders report overlaps, while a SolidWorld keeps a mover out of them. For platformer tiles (including one-way platforms) see BGE.resolveAabbTileCollision() instead.

Example

CODE
world = new BGE.SolidWorld()
world.addBounds(0, 0, mapWidth, mapHeight)
world.addSolid(64, 64, 32, 32)
' Each frame, move the player's feet box:
result = world.moveAndSlide({x: feetX, y: feetY, w: 20, h: 12}, dx, dy)
feetX = result.x
feetY = result.y

Constructor

new SolidWorld(bucketSize?: integer): SolidWorld

Parameters

  • bucketSize (integer, optional, default: 128) — solids are grouped in square cells this size (px), so a move only tests nearby solids. Roughly the size of a typical solid works well. 0 or less uses the default.

Instance Methods

addSolid(x: float, y: float, w: float, h: float): void

Adds a solid rectangle.

Parameters

  • x (float) — bottom-left x
  • y (float) — bottom-left y
  • w (float)
  • h (float)

Returns

  • void

addBounds( x: float, y: float, w: float, h: float, thickness?: float, ): void

Adds four solids around the outside of a rectangle, so movers can't leave it (e.g. the edges of a map).

Parameters

  • x (float) — bottom-left x of the area to keep movers inside
  • y (float) — bottom-left y
  • w (float)
  • h (float)
  • thickness (float, optional, default: 64) — how thick each wall is

Returns

  • void

getSolidCount(): integer

Returns

  • integer — how many solids have been added

getSolids(): Array.<BGE.SolidWorldSolid>

Every solid added so far, e.g. for drawing them while debugging. Each is a copy, so changing one doesn't move the real solid.

Returns

isAreaFree(x: float, y: float, w: float, h: float): boolean

Whether a box overlaps no solid. A box only touching a solid's edge is free.

Parameters

  • x (float) — bottom-left x
  • y (float) — bottom-left y
  • w (float)
  • h (float)

Returns

  • boolean

moveAndSlide( mover: object, dx: float, dy: float, options?: BGE.SlideOptions, ): BGE.SlideResult

Moves a box by (dx, dy), stopping flush against solids and sliding along them. When moving along one axis only, a box that clips a corner by up to options.cornerNudge is eased around it. The box must start clear of every solid.

Parameters

  • mover (object) — {x, y, w, h}: the moving box, bottom-left corner
  • dx (float)
  • dy (float)
  • options (BGE.SlideOptions, optional, default: "{}") — cornerNudge (default 8, 0 = off), maxStep (default 4)

Returns

  • BGE.SlideResult — the box's new bottom-left corner, and which axes were blocked