SandGame/fire.js

import { grid, cols, rows } from './state.js';
import { config } from './config.js';
import { move } from './actions.js';
import { createCell } from './physics.js';
import { explode } from './explosive.js';

const dxs = [0, 0, -1, 1];
const dys = [1, -1, 0, 0];

export function updateFire(x, y, cell) {
    if (cell.lifespan === undefined) {
        cell.lifespan = Math.floor(Math.random() * 20) + 10;
        cell.maxLife = cell.lifespan;
    }

    cell.lifespan--;

    // Color shift as fire cools: yellow -> orange -> ember red
    const lifeRatio = cell.lifespan / (cell.maxLife || 25);
    if (lifeRatio > 0.6) {
        cell.u32Color = 0xFF70F0FF; // Bright yellow-white (ABGR)
    } else if (lifeRatio > 0.3) {
        cell.u32Color = 0xFF0080FF; // Intense flame orange
    } else {
        cell.u32Color = 0xFF0025D0; // Deep ember red
    }

    // Death / decay -> spawn smoke
    if (cell.lifespan <= 0 || Math.random() < config.fire.burnChance) {
        if (Math.random() < 0.65) {
            grid[x][y] = createCell('smoke');
        } else {
            grid[x][y] = null;
        }
        return;
    }

    // Extinguish if suffocated by solid matter
    let airNeighbor = false;
    for (let i = 0; i < 4; i++) {
        const nx = x + dxs[i];
        const ny = y + dys[i];
        if (nx >= 0 && nx < cols && ny >= 0 && ny < rows) {
            const n = grid[nx][ny];
            if (!n || n.type === 'steam' || n.type === 'smoke') {
                airNeighbor = true;
                break;
            }
        }
    }
    if (!airNeighbor && Math.random() < 0.2) {
        grid[x][y] = null;
        return;
    }

    // Spread to flammable neighbors
    for (let i = 0; i < 4; i++) {
        const nx = x + dxs[i];
        const ny = y + dys[i];
        if (nx >= 0 && nx < cols && ny >= 0 && ny < rows) {
            const n = grid[nx][ny];
            if (n) {
                const nt = n.type;
                if (nt === 'water' || nt === 'ice') {
                    grid[x][y] = null; // Fire extinguished
                    grid[nx][ny] = createCell('steam');
                    return;
                } else if (nt === 'explosive') {
                    explode(nx, ny);
                    return;
                } else if (nt === 'oil') {
                    grid[nx][ny] = createCell('fire');
                } else if (nt === 'plant' && Math.random() < config.plant.burnChance) {
                    grid[nx][ny] = createCell('fire');
                } else if (nt === 'grass' && Math.random() < config.grass.burnChance) {
                    grid[nx][ny] = createCell('fire');
                } else if (nt === 'wood' && Math.random() < config.wood.burnChance) {
                    grid[nx][ny] = createCell('fire');
                }
            }
        }
    }

    // Rise / flicker randomly upwards
    const dx = Math.floor(Math.random() * 3) - 1;
    const dy = -Math.floor(Math.random() * 2); // Rise: 0 or -1
    const nx = x + dx;
    const ny = y + dy;
    if (nx >= 0 && nx < cols && ny >= 0 && ny < rows && !grid[nx][ny]) {
        move(x, y, nx, ny);
    }
}