● 本博客使用CC 3.0协议,转载请保留该信息。
● 原文作者: 戴晓天 @ 云飞机器人实验室
● 原文地址: Robocode常见问题

本文由 云飞机器人实验室 翻译。

What is the difference between frames and ticks?
A tick refers to one unit, which is also called a Turn in Robocode. During one turn, you may perform one action as a Robot, or multiple (independent) actions as an AdvancedRobot. A frame is a unit of drawing to the Robocode client interface. If you are processing turns slowly, you will get one frame per tick / turn. However, if you up the turns per second beyond your computer’s ability to render the frames, you will miss some frames of animation. This won’t affect the robots’ behavior, unless you foolishly added code in your onPaint(Graphics2D) method that alters your bots behavior. In that case, your bot will behave differently depending on whether or not the Paint button has been enabled, and if the framerate can keep up with the turnrate.

Can I fire bullets with power higher than 3.0 or lower than 1.0?
No and yes. You can’t fire bullets with power greater than 3.0, but you can fire bullets with power as low as 0.1. If you call a firing function (i.e. setFire()) with a value greater than 3.0, Robocode will adjust it to 3.0, and if you call it with a power lower than 0.1 (except 0.0 which will not fire) it will adjust it to 0.1. Additionally, you can fire bullets with power less than 0.1 under one condition: when your robot has less than 0.1 energy left, in which case a bullet is fired with however much energy your robot had left.

How fast does a bullet travel?
A bullet travels at a speed between 11.0 and 19.7 depending on the power. The more powerful the bullet, the slower. The formula to calculate it is velocity = 20 – (3 * power).
子弹的速度与能量相关,介于11.0-19.7之间,能量越大,速度越慢。计算公式是:速度 = 20 – (3 * 能量).

Does the robot velocity get added to the bullet velocity on firing?
No, bullet velocity is not affected by robot velocity. It’s kind of like the speed-of-light thing. =)

Which is the range of a bullet?
A bullet has no range. It keeps going until it hits a robot or a wall.

I want to fire a bullet every turn, but I can’t. Why?
我可以在每个回合(turn,also known as tick)发射子弹么?为什么?
Every time you fire, the gun generates some heat. You must wait till it is cool again to fire. If you give a fire order when your gun is hot, it will do nothing. The heat generated by a shot is 1 + (firepower / 5). The gun cools down at a default rate of 0.1 per turn (note that you can change this parameter when you run the battle, but nobody usually does). It means you can fire a 3.0 power bullet every 16 ticks.
不可以,每当你发射子弹时,会产生炮管热量,当你在炮管没有冷却之前,发射子弹的命令不会响应。热量产生的公式是:1 + (子弹能量 / 5)。炮管热量以0.1/回合的速度耗散,这意味着每16个回合才能发射一颗3.0能量的子弹。

How much damage does a bullet do? How do I gain or lose energy?
You lose energy every time you hit a wall, you are hit by an enemy bullet, ram an enemy, or you fire your gun. The amount of energy you lose by being hit is 4 * bullet power + 2 * max(bullet power – 1 , 0). So the maximum amount is 16.0. When you fire, you spend a quantity of energy equal to the power of the bullet fired. When one of your bullets hits an enemy, you collect back 3 * bullet power energy. When you hit an enemy bot, each bot takes 0.6 damage. If an AdvancedRobot (but not a Robot or JuniorRobot) hits a wall, it will take max(abs(velocity) * 0.5 – 1, 0) damage.
每当你撞墙、被敌人击中、与敌人碰撞或者你发射子弹时,你都会损失能量。被击中时的能量损失的公式是:4 * 子弹能量 + 2 * max(子弹能量 – 1 , 0)。所以最大损失的能量是16。当你发射子弹时,你损失的能量与子弹能量相当。当你击中敌人时,你可以得到3*子弹能量的反馈。当你与别人撞击时,双方都会损失0.6的能量。如果一个AdvanceRobot(Robot、JuniorRobot不会)撞墙了,会损失max(abs(速度) * 0.5 – 1, 0) 的能量。

Some times I get disabled. What happens?
You can’t kill yourself, so when your energy drops to zero because you hit a wall or you fire, your bot gets disabled. It will not be able to move nor fire. If you are lucky enough and one of your bullets in the air hits an enemy, you will get some energy back and recover from disabled status.

I get disabled, but I my energy > 0. Why?
There are a few possible causes. You may have called a getXXX() function – such as getVelocity() – too many times a turn. The limit is 10000 getXXX() function calls per turn. To avoid disabling in such situations, either store returned values in variables for future use or use a RobotStatus object obtained from StatusEvent. Another case in which you can get disabled is throwing an exception, which may disable your bot, even if you catch the exception. Also, if your bot gets stuck in an infinite (or very long) loop and skips many turns, it may also get disabled.

How fast do I move?
You can move at a maximum speed of 8.0 units/tick. You can modify (down) your maximum velocity by using setMaxVelocity(…). Note that your bot will always accelerate to reach its maximum velocity.

How fast do I accelerate?
You accelerate at 1 unit/tick, and you decelerate at 2 units/tick. For example, if you are moving at an speed of 8.0 and reverse your direction your velocities will be [6.0, 4.0, 2.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0].
加速度为1个单位/回合;减速度为2个单位/回合。如果你以8.0的速度反向运动,你的速度将会是[6.0, 4.0, 2.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0]。

How fast do I turn?
The faster you go, the slower you turn. The formula to calculate it in degrees is 10 – 0.75 * abs(velocity).
你速度越快转弯就越慢。计算公式是:10 – 0.75 * abs(velocity).

What is the size of a bot?
The size of a bot is 36×36. Note, this is slightly smaller than the image of the bot. It is modeled as a non rotating square, so it’s always the same regardless of its heading.

It seems that Robocode doesn’t follow standard physics. If my velocity is 0 and I accelerate (acceleration = 1) my final position is 1, but it should be 0.5. What happened?
Time in Robocode, rather than being continuous, is in discrete “ticks”. First acceleration is calculated, then velocity, and then position. So if you are stopped at a position 0 and you accelerate 1, your velocity next turn will be 1 and your position also 1.

How can I detect when an enemy has fired?
There is no direct way to detect when an enemy fired, but you can deduce it by monitoring the enemy energy drop. A drop between 0.1 and 3 usually means that it fired a bullet (there can be other reasons, such as a low energy bullet hit or a wall hit). Wall hits are (more or less) detectable as well. A deceleration > 2 means the bot hit a wall (or another bot). A deceleration <= 2 may be simple a bot hitting the brakes, or hitting a wall at velocity = 2, but since hitting a wall at that speed won’t cause any damage, you can ignore that. AdvancedRobots take abs(velocity) / 2 – 1 (Never < 0) damage when hitting a wall, so by detecting (significant) wall-hits and adjusting the enemy drop accordingly, wall hits can be filtered out most of the time. This method fails when the enemy hits another robot.
没有直接的方法直到敌人开火了,但是可以间接的通过监视对方的能量得知。介于0.1-3.0之间的能量降落通常被认为是发射了子弹。当然也有可能是中了能量很小的子弹或是发生了碰撞。实际上碰撞是可以被检测的,当机器人减速度大于2时,就认为发生了碰墙;减速度小于2,可能是它刹车了,或是正好以2的速度撞墙(不过此时几乎没有伤害)。AdvancedRobots撞墙时会损失abs(velocity) / 2 – 1的能量,所以通过检测碰墙,就可以更好的确定敌人开火了。当然,对于机器人之间的碰撞,这种方法无能为力。

How can I detect the position and heading of an enemy bullet?
You can’t. There is no way to know it, directly or indirectly. But of course, you can always guess

How fast can I turn my gun?
The gun turns at 20 degrees per tick.

How fast can I turn my radar?
It turns 45 degrees per tick.

Can I know the heading of the enemy gun/radar?

Can I specify the initial position of my bot?
No. The bots are randomly placed in the field at the beginning of each round.

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