How to integrate computing time in AI reaction? - lua

Question

My program is an implementation of Pong where one of the paddles is to be moved by the computer and the other by the user.
The program works fine with errors being made by the AI for realism. However, the movement of my paddle on screen is stuttering and it seems to be skipping one or two frames.
The program is in Lua(+Love2D).
function Paddle:comp_move(dt)
error = math.random(3) == 2 and true or false
start_time = os.time()
diff = 0
if ball:collides(self) == false then
if ball.y > self.y + self.height then -- Ball is below paddle
-- Ball is moving up and difference is more than 20 pixels
if ball.dy < 0 and (ball.y - self.y - self.height) > 20 then
-- move down
if error == false then
diff = os.difftime(os.time() - start_time)
self.y = math.min(VIRTUAL_HEIGHT - 20, self.y + PADDLE_SPEED*(dt))
end
end
-- Ball is moving down
if ball.dy > 0 then
-- move down
if error == false then
diff = os.difftime(os.time() - start_time)
self.y = math.min(VIRTUAL_HEIGHT - 20, self.y + PADDLE_SPEED*(dt))
end
end
elseif ball.y + ball.height < self.y then -- Ball is above paddle
-- Ball is moving down
if ball.dy > 0 and (self.y - ball.y - ball.height) > 20 then
-- move up
if error == false then
diff = os.difftime(os.time() - start_time)
self.y = math.max(0,self.y - PADDLE_SPEED*(dt))
end
elseif ball.dy < 0 then -- Ball is moving up
-- move up
if error == false then
diff = os.difftime(os.time() - start_time)
self.y = math.max(0,self.y - PADDLE_SPEED*(dt))
end
end
end
end
I am calculating the time taken to compute by the PC but what operation should i do with it normalize my paddle's movement.

Answer 1

From your code it seems the paddle speed is constant; it might be an idea to replace this by a function, so that initially the paddle moves more slowly, then speeds up, and then slows down again as it arrives at the desired location.
This would make it more realistic in terms of movement behaviour, and it might also solve your problem of stuttering.
Your constant PADDLE_SPEED would need to be replaced by some function that takes a step and returns a value (probably between 0.0 and PADDLE_SPEED) at the appropriate time.