Method isLineClear

plugins/pathFinder.js:626–731

Check that the line between two tile-coord endpoints stays entirely * inside walkable, zero-cost cells. Stricter than just sampling along * the line — it also checks the diagonal-corner-adjacent cells so the * line can never "scrape past" a wall corner. * * Both endpoint

(startPos, endPos)

     *  @returns {boolean}
     *  @private */
    isLineClear(startPos, endPos)
    {
        ASSERT(isVector2(startPos) && isVector2(endPos), 'isLineClear needs Vector2 endpoints');
        ASSERT(this.isNodeClear(startPos.x, startPos.y) && this.isNodeClear(endPos.x, endPos.y),
            'isLineClear endpoints must be in-bounds and clear');

        const dx = endPos.x - startPos.x;
        const dy = endPos.y - startPos.y;
        const adx = abs(dx);
        const ady = abs(dy);
        const sx = sign(dx);
        const sy = sign(dy);
        let x = startPos.x;
        let y = startPos.y;

        if (ady === adx)
        {
            // Pure diagonal.
            while (x !== endPos.x)
            {
                if (x !== startPos.x)
                {
                    if (!this.isNodeClear(x, y)) return false;
                    if (!this.isNodeClear(x, y - sy)) return false;
                }
                if (!this.isNodeClear(x, y + sy)) return false;
                x += sx;
                y += sy;
            }
            if (!this.isNodeClear(endPos.x, endPos.y - sy)) return false;
        }
        else if (ady < adx)
        {
            // Mostly horizontal.
            if (dy === 0)
            {
                // Purely horizontal.
                x += sx;
                while (x !== endPos.x)
                {
                    if (!this.isNodeClear(x, y)) return false;
                    x += sx;
                }
            }
            else
            {
                let lastY = startPos.y;
                while (x !== endPos.x)
                {
                    y = startPos.y + Math.trunc((dy * (x - startPos.x)) / dx);
                    if (lastY !== y)
                    {
                        if (!this.isNodeClear(x - sx, y + sy)) return false;
                        if (!this.isNodeClear(x, y - sy)) return false;
                    }
                    lastY = y;
                    if (x !== startPos.x)
                    {