SandGame/dirt.js

import { grid, cols, rows } from './state.js';
import { move, swap } from './actions.js';

export function updateDirt(x, y, cell) {
    const below = y + 1;
    if (below >= rows) return;

    const belowCell = grid[x][below];
    if (!belowCell) {
        move(x, y, x, below);
        return;
    }

    // Sinks through liquids (water, acid, oil)
    if (belowCell.type === 'water' || belowCell.type === 'acid' || belowCell.type === 'oil') {
        if (Math.random() < 0.35) {
            swap(x, y, x, below);
        }
        return;
    }

    // Slide diagonally down left or right
    const canDownLeft = x > 0 && (!grid[x - 1][below] || isDisplaceableLiquid(grid[x - 1][below]));
    const canDownRight = x < cols - 1 && (!grid[x + 1][below] || isDisplaceableLiquid(grid[x + 1][below]));

    if (canDownLeft && canDownRight) {
        const targetX = Math.random() < 0.5 ? x - 1 : x + 1;
        executeMove(x, y, targetX, below);
    } else if (canDownLeft) {
        executeMove(x, y, x - 1, below);
    } else if (canDownRight) {
        executeMove(x, y, x + 1, below);
    }
}

function isDisplaceableLiquid(target) {
    return target && (target.type === 'water' || target.type === 'acid' || target.type === 'oil');
}

function executeMove(x1, y1, x2, y2) {
    if (grid[x2][y2]) {
        swap(x1, y1, x2, y2);
    } else {
        move(x1, y1, x2, y2);
    }
}