---
title: "Visibility and line of sight"
package: "@phaser-ae/visibility-2d"
tier: Free
version: 3.0.0-4
released: 2026-10-14
updated: 2026-10-20
description: "Answers the three questions a 2D game asks of its walls, what can be seen from here, can this point see that one, and what does a ray hit first."
url: https://phaser.io/packs/visibility-2d
site: Phaser - https://phaser.io
---

# Visibility and line of sight

A set of wall segments and the three questions a game asks of them: what can be seen from here, can A see B, and what
does a ray hit first. It is pure geometry on the CPU, cheap enough for AI to ask every step.

## What it does

`game.visibility.create()` makes a set, and you fill it with the level's walls: single segments, the four edges of a
rectangle, or the edges of a polygon. Each segment is a plain object, so moving a door or a crate is a matter of
changing its numbers, and `remove` and `clear` take walls away.

`visibility(x, y, range)` returns the visibility polygon: the points a viewer at (x, y) can see to, in angle order,
ready to fan into triangles and draw as a light or a fog mask. It uses the classic method, a ray cast just either side
of every segment corner with the nearest hit kept, which is exact and leaves no holes. `canSee` says whether the
straight line between two points is within range and crosses no wall, the question a guard asks about the player.
`raycast` returns the first hit along a ray, with its point and distance, for a hit-scan weapon or a laser.

Optional bounds are a rectangle every ray stops at, usually the camera's view, so a polygon in an open world stays
finite. The class, `Visibility2d`, is exported too, so a pack or a worker can use it without the game.

## Features

- **Visibility polygons** — the fan of points a viewer sees within a range, in angle order.
- **Line of sight** — `canSee` between two points, with a maximum distance.
- **Raycasts** — the nearest hit point and its distance along any direction.
- **Walls from shapes** — `addSegment`, `addRect` and `addPoly`, from points or a flat list, closed or open.
- **Moving walls** — change a segment's fields to move it, with nothing to rebuild.
- **Bounds** — `setBounds` stops rays at a rectangle, such as the camera's view.

## Good for

- **Stealth games**: can the guard see the player, and what does the guard's view cover.
- **Fog of war in a continuous world**, drawing what the player can see as a mask.
- **Shadowed 2D lights**, through the lighting pack.
- **Hit-scan weapons and lasers** that stop at the first wall.
- **Top-down shooters with free-form walls**, where enemies react only to what they can see.

## Make it yours

The pack has no options: a set is its walls and its bounds. Two different uses: a stealth level where each guard calls
`canSee` towards the player within 400 units every step, and the player's own view is drawn from `visibility` as a
darkness mask; and a lit scene where the same walls cast shadows from every light, with no fog at all.

## A quick look

Walls of three kinds, then the three questions:

```ts
const v = game.visibility.create({ x: 0, y: 0, w: 640, h: 360 });   // bounds rays always stop at
v.addRect(100, 80, 32, 32);                        // four walls
v.addPoly([0, 0, 50, 10, 40, 60]);                 // a closed polygon
const wall = v.addSegment(0, 200, 640, 200);       // one wall; change wall.x1 and the rest to move it
const poly = v.visibility(px, py, 300);            // points in angle order within 300 units
const seen = v.canSee(guard.x, guard.y, hero.x, hero.y, 400);
const hit = v.raycast(ox, oy, dx, dy, 500);        // { x, y, dist } of the nearest hit, or null
```

## Works with

- `lighting-2d` — shadowed point lights, which keep one of these sets as their occluders.
- `stealth` — guards with sight, hearing, suspicion and search, built on this pack.
- `fog` — a tile-grid fog of war that remembers what was seen, the alternative for tile maps.

## Good to know

- The cost is rays times segments per call: hundreds of segments and a handful of polygons a frame is comfortable,
  and for big maps you merge runs of tiles into long segments.
- With no walls in range, no bounds and no range limit, `visibility` returns an empty list: set bounds in an open
  world.
- `canSee` ignores the bounds, while `raycast` and `visibility` include them.
- Segments have no thickness and no inside, and there is no spatial index: every call scans every segment.
- It is 2D only.

---

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