关于坦克大战—子弹与瓦片碰撞问题的一些感想

废话不多说，想上代码

完整代码：https://github.com/ytbLib/Tank_Battle

 /**
     * @function 子弹与瓦片的碰撞
     * @param bullet  子弹类
     * @return {boolean} 如果碰撞，返回true
     */
    function bullet_Tile_Collision(bullet) {
        var result = false;
        var rowIndex = 0;      //行索引
        var colIndex = 0;      //列索引
        var tileNum = 0;       //击中的瓦片数

        //根据子弹的起始坐标判断当前子弹所在瓦片的索引
        //不同方向获取索引的方式不同
        if (bullet.dir == UP){
            rowIndex = parseInt((bullet.y - map.offsetY) / map.tileSize);
            colIndex = parseInt((bullet.x - map.offsetX) / map.tileSize);
        } else if (bullet.dir == DOWN){
            rowIndex = parseInt((bullet.y - map.offsetY + bullet.size) / map.tileSize);
            colIndex = parseInt((bullet.x - map.offsetX) / map.tileSize);
        } else if (bullet.dir == LEFT){
            rowIndex = parseInt((bullet.y - map.offsetY) / map.tileSize);
            colIndex = parseInt((bullet.x - map.offsetX) / map.tileSize);
        } else if (bullet.dir == RIGHT){
            rowIndex = parseInt((bullet.y - map.offsetY) / map.tileSize);
            colIndex = parseInt((bullet.x - map.offsetX + bullet.size) / map.tileSize);
        }

        //当子弹越界时
        if (colIndex >= map.tileCountWidth || colIndex < 0 ||
            rowIndex >= map.tileCountHeight || colIndex < 0){
            return true;
        }

        //当子弹方向为上或者下时，判断地图列方向应该打掉多少块瓦片
        if (bullet.dir == UP || bullet.dir == DOWN){
            //子弹右边距距离当前瓦片起始x坐标的宽度
            var wBulletInCurTile = parseInt(bullet.x - map.offsetX - (colIndex * map.tileSize) + bullet.size);
            //当子弹右边距在瓦片边界时,
            if (wBulletInCurTile % map.tileSize == 0){
                tileNum = parseInt(wBulletInCurTile / map.tileSize);
            } else { //当子弹右边距当前瓦片内部或者超过瓦片时
                tileNum = parseInt(wBulletInCurTile / map.tileSize) + 1;
            }

            for (var i = 0; i < tileNum && colIndex + i < map.tileCountWidth; i++){
                var tempTile = map.mapLevel[rowIndex][colIndex + i];
                if (tempTile == NORMAL_BRICK || tempTile == DIAMOND_BRICK){
                    result = true;
                    if (tempTile == NORMAL_BRICK){
                        map.mapLevel[rowIndex][colIndex + i] = 0;
                    } else if (tempTile == DIAMOND_BRICK){

                    }
                }
            }
        } else if (bullet.dir == LEFT || bullet.dir == RIGHT){
            //子弹下边距距离当前瓦片起始y坐标的高度
            var hBulletInCurTile = parseInt(bullet.y - map.offsetY - (rowIndex * map.tileSize) + bullet.size);
            //当子弹下边距在瓦片边界时,
            if (hBulletInCurTile % map.tileSize == 0){
                tileNum = parseInt(hBulletInCurTile / map.tileSize);
            } else { //当子弹下边距当前瓦片内部或者超过瓦片时
                tileNum = parseInt(hBulletInCurTile / map.tileSize) + 1;
            }

            for (var i = 0; i < tileNum && rowIndex + i < map.tileCountWidth; i++){
                var tempTile = map.mapLevel[rowIndex + i][colIndex];
                if (tempTile == NORMAL_BRICK || tempTile == DIAMOND_BRICK){
                    result = true;
                    if (tempTile == NORMAL_BRICK){
                        //把当前瓦片清除
                        map.mapLevel[rowIndex + i][colIndex] = 0;
                    } else if (tempTile == DIAMOND_BRICK){

                    }
                }
            }
        }

        return result;
    };

详解+图解：