Computer Science Canada

Make the A.I Paddle follow the ball
Author:  Velocity [ Wed Dec 21, 2011 7:28 pm ]
Post subject:  Make the A.I Paddle follow the ball
What is it you are trying to achieve?
I aim to make the A.I Paddle follow the ball so that it never goes below it.

What is the problem you are having?
I am unable to make the paddle move first of all but i think this is just the same step as making it follow the ball so i want to make it follow the ball.


Describe what you have tried to solve this problem
making if statements for if the paddle is greater than this location paddle -= 10 and if it is less than this location it goes += 10, it doesnt move, it stays still

Post any relevant code (You may choose to attach the file instead of posting the code if it is too long)
Turing:


if ball_y2 >= maxy - 50 then
            ball_directiony2 *= -1
        end if
        if ball_x2 >= maxx div 2 + 40 then
            ball_directionx2 *= -1
        end if
        if ball_x2 <= maxx - 40  then
            ball_directionx2 *= -1
        end if
        var direction1 : int
        ball_x2 += (ball_directionx2 * ball_speed)
        ball_y2 += (ball_directiony2 * ball_speed)
        if ball_x2 <= x2_2 and ball_y2 <= y2_2 + 15 and ball_x2 >= x1_1 and ball_y2 >= y1_1 + 15 then
            ball_directiony2 *= -1
end if
%%% above is my syntax to make my ball move

% I want to know how to make the paddle :

    x1_1 := 750
    y1_1 := 25
    x2_2 := 850
    y2_2 := 50
    drawfillbox (x1_1, y1_1, x2_2, y2_2, 131)
% follow the ball and the collision part i got covered.



Please specify what version of Turing you are using
4.1.1a
Author:  Velocity [ Wed Dec 21, 2011 7:50 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
+ karma for help, need to make it in the next 10mins
Author:  RandomLetters [ Wed Dec 21, 2011 9:05 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
If you want it to follow the ball, then you will need to use the ball's coordinates somehow.

A simple way is to just draw the paddle where the ball is

x1 = 10
x2 = 20
y1 = by + 10
y2 = by - 10

better (beatable way) is to check the location of the paddle, compare it to the location of the ball, and move appropriately

for example,
y = 0

if deltay > max then //check if the paddle is above the ball and set it to move down
v = -1
end if

y += v
y1= y + 10
y2 = y - 10
Author:  Zren [ Wed Dec 21, 2011 10:36 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
So much hardcoding... If you use a number more than once for a specific value (Eg: ball radius, ball speed, paddle speed) then you should make a variable or constant for it. Actually, you should always use a variable to describe 'magic numbers' even if you only use the variable once. It makes the code more readable.

Building on what Rand was talking about:
You also need to take into account when the object's destination is within the movement speed. Otherwise you'll get a jittery effect as one frame it's on the left, next on the right, etc.

Turing:

var delta := ball.pos.x - paddle.pos.x % d = p2 - p1

if abs (delta) <= paddle.speed then
    % Will reach destination this tick.
    paddle.nextPos.x := ball.pos.x
elsif delta > 0 then
    % Destination is to the right
    paddle.nextPos.x := paddle.pos.x + paddle.speed
elsif delta < 0 then
    % Destination is to the left
    paddle.nextPos.x := paddle.pos.x - paddle.speed
end if
Author:  Velocity [ Thu Dec 22, 2011 12:17 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
zren i implemented your code into my program and changed the co-ords around a little, and the a.i paddle moves where the ball is but it only twitches like + 5 on the co-ord that way... so it doesnt exactly follow it only + 5 out of 100, this is how i put your code in :

var paddle_speed : int := 5
var shadower := ball_x2 - x2_2
if abs (shadower) <= paddle_speed then
x2_2 := ball_x2
x1_1 := ball_x2
elsif shadower > 100 then
x1_1 := x1_1 + paddle_speed + 100
x1_1 := x2_2 - paddle_speed - 100
elsif shadower < 100 then
x2_2 := x1_1 - paddle_speed - 100
x2_2 := x1_1 + paddle_speed + 100
end if
Author:  Velocity [ Thu Dec 22, 2011 12:21 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
This changed the paddle speed but ithen the paddle moves and it gets to the maxx and disappears

var paddle_speed : int := 50
var shadower := ball_x2 - x2_2
if abs (shadower) <= paddle_speed then
x2_2 := ball_x2
x1_1 := ball_x2
elsif shadower > 100 then
x1_1 := x1_1 + paddle_speed + 200
elsif shadower < 100 then
x2_2 := x1_1 - paddle_speed - 100
end if
Author:  Insectoid [ Thu Dec 22, 2011 1:01 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
You're severely over-complicating this.

code:

if ball_y < paddle_y then
    move_paddle_down
else if ball_y > paddle_y then
    move_paddle_up
end if


It's that simple.
Author:  Velocity [ Thu Dec 22, 2011 6:12 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
insectoid thank you so much that helped alot! +karma
Author:  Velocity [ Thu Dec 22, 2011 6:46 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
if ball_y2 > x1_1 then
x2_2 += 10
x1_1 += 10
elsif ball_y2 < x1_1 then
x2_2 -= 10
x1_1 -= 10
end if

insectoid i used your code but for some reason with these boundaries of my paddle

if x2_2 > maxx - 31 and x1_1 < maxx - 131 then
x1_1 -= 10
x2_2 -= 10
elsif x2_2 < maxx div 2 + 131 and x1_1 > maxx div 2
+ 31 then
x1_1 += 10
x2_2 += 10
end if

the paddle goes to the left and then even when the ball moves right the paddle trys to move right but stays on the left.
Author:  Dreadnought [ Thu Dec 22, 2011 7:06 pm ]
Post subject:  Re: Make the A.I Paddle follow the ball
Is it intended that you're comparing the y-coordinate of the ball with the x coordinate of the paddle?
Author:  Insectoid [ Thu Dec 22, 2011 8:11 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
The paddle doesn't even need an X variable, since it only goes up and down.
Author:  Velocity [ Thu Dec 22, 2011 10:35 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
mine goes left and right
Author:  Velocity [ Thu Dec 22, 2011 10:35 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
its not pong, its brick breaker. Please help me to know where i went wrong Smile
Author:  RandomLetters [ Thu Dec 22, 2011 11:04 pm ]
Post subject:  RE:Make the A.I Paddle follow the ball
Then why are you comparing the y values of the paddle?
Author:  Velocity [ Fri Dec 23, 2011 1:11 am ]
Post subject:  RE:Make the A.I Paddle follow the ball
X1-1 is the first x co'ord of the paddle
X2-2 is the second x co'ord of the paddle
Ball-y2 is the y co'ord of the a.i ball

Nowhere in the code does it say the y co'ord of the paddle

X1-1 is where the drawfill box starts
X2-2 is where it ends

How do i get my paddle to follow the ball properly, the code i prompted it with worked but when my code starts the a.i paddle goes to the left and trys to go right but a force blocks it and it doesnt. Would you feel more comfortable with my question if i provided the code for my actual game?
Author:  Velocity [ Fri Dec 23, 2011 1:14 am ]
Post subject:  RE:Make the A.I Paddle follow the ball
oh wait i think i see the problem, ill try to fix it tomorrow when i get on the comp, dreadnought thanks your post shined a light in my eyess Smile.
Author:  Zren [ Fri Dec 23, 2011 1:26 am ]
Post subject:  RE:Make the A.I Paddle follow the ball
Need Code: Yes.

What he means is why are you comparing the paddle.pos.x to ball.pos.y? The relation is on the x-axis, so you'd be comparing both x values. This is a one dimensional problem.

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