Module threat 

Threat areas over a square grid: the tiles a piece can strike next turn (strike_area, strike_area_from), which threats reach a tile and whether it is safe (Threats), how much danger a tile stands in by the game’s own forecast (Threats::danger), and how far a piece would walk from a tile to the nearest of some goals (GoalDistance). It is the danger zone a player reads: a bot that plays like a person keeps out of it, a roguelike draws a monster’s reach as an overlay, a tower-defense game shows a tower’s coverage. On them, TacticsOrder lists the few commands a planning bot tries first: every piece’s best strike, then each piece’s step towards the goals and its step to safety, and the end of the turn always kept (OrderHooks, Kind).

Rules

• Ranges. A strike range is an inclusive pair of Manhattan distances, (min, max), as Pos::manhattan counts them; a pair with min > max is empty. A piece’s Ranges are all of its weapons, spells or arcs.
• Areas. A piece strikes every tile of the grid within one of its ranges of a tile it can stop on, and the stop tiles themselves when it has any range at all: a piece that can strike threatens where it can stand. Which tiles it can stop on is the game’s: most often the tiles of its Reach (reachable) that no other piece holds. A piece that never moves strikes from where it stands (strike_area_from).
• Every threat counts. Threats::danger adds up the forecast of every threat that reaches a tile; it never guesses which one the other side will choose. A bot that knows the danger zone and the forecasts a player reads, and never whom the other side will strike, plays fair.
• Cost. Building an area walks a diamond around each stop tile, row by row, clipped to the grid: stops × (rows × ranges + the tiles in range). Threats::reaches and Threats::safe look up one bit per threat and allocate nothing.

A piece at P on a 5 × 5 grid stops on the o tiles (and on its own) and strikes at 1 to 2. Its area is every tile but the three .:

 stops      area
 . . . . .  x x x x .
 . o o . .  x x x x x
 . o P o .  x x x x x
 . . o . .  x x x x x
 . . . . .  . x x x .

use shuyi_core::{Pos, TileSet, strike_area};

let mut stops = TileSet::new(5, 5);
for (x, y) in [(2, 2), (1, 1), (2, 1), (1, 2), (3, 2), (2, 3)] {
    stops.insert(Pos::new(x, y));
}
let area = strike_area(&stops, &[(1, 2)]);
assert_eq!(area.len(), 25 - 3);
for (x, y) in [(4, 0), (0, 4), (4, 4)] {
    assert!(!area.contains(Pos::new(x, y)));
}

Structs

Danger

The danger at one tile: Threats::danger’s sums of the Strikes of every threat that reaches it.

GoalDistance

How far a piece would walk from a tile to the nearest of some goals, with one flow_field per movement kind K, built on first use and kept. Stepping onto a goal’s own tile is free and always allowed: a goal is often a tile another piece stands on.

Strike

The game’s forecast of one threat’s strike on whoever stands on a tile. Expected values are in hundredths of a point: a hit chance in percent times the damage.

TacticsOrder

A planner’s candidate order for grid games, in eight steps (the module’s docs): every piece’s best strike, the game’s pick, its extras, each piece’s advance and hold, the other strikes, the rest, and the end of the turn within cap.

Threat

One piece that threatens tiles: the game’s id for it and the tiles it can strike next turn.

Threats

The threats of one side, in the game’s order. Answers which reach a tile, whether a tile is safe, the danger zone, and the danger at a tile by the game’s forecast.

Enums

Kind

What a legal command is to a TacticsOrder. P is the game’s id of a piece.

Traits

OrderHooks

What a TacticsOrder asks the game, once per order call. The game’s hooks hold the state’s Threats and GoalDistance, built in prepare.

Functions

strike_area

The tiles a piece that can stop on stops strikes with ranges: every tile of the set’s grid within one of ranges of a stop tile, and the stop tiles themselves when ranges is not empty. Empty ranges strike nothing. See the module docs for the cost.

strike_area_from

The tiles a piece that never moves, standing on at, strikes with ranges on a width × height grid: strike_area with at its only stop. A tile outside the grid strikes nothing.

Type Aliases

Ranges

A piece’s strike ranges: inclusive pairs of Manhattan distances (min, max). A pair with min > max is empty.