Pong game/Angles questions

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Dec 11th, 2002, 10:02 AM
cyborg

Pong game/Angles questions
hi!
im making a pong game like dxball (http://www.longbowdigitalarts.com)...

When i shoot the ball i want it to move in a specific angle...
how do i do that?

i've tried this code:
VB Code:
```
Ball(i).x = Ball(i).x + Sin(Ball(i).Angle) * 5
        Ball(i).y = Ball(i).y + Cos(Ball(i).Angle) * 5
```
but it doesnt move where it should all the time....
whats wrong?
Dec 11th, 2002, 10:06 AM
cyborg

If i get some more questions about this pong game, i will post them in this thread!
Dec 11th, 2002, 11:46 AM
/\/\isanThr0p

well on the first look the code seems right.
but if you declared the x and the y variable as integers you will probably get a bad movement... try declaring them as singles or scale your numbersystem up (dunno some people like not to use float values :))

this solved the problem:

VB Code:

Ball(i).X = Ball(i).X + Sin(Ball(i).Angle * (Pi / 180)) * Ball(i).Speed
    Ball(i).Y = Ball(i).Y + Cos(Ball(i).Angle * (Pi / 180)) * Ball(i).Speed

Dec 11th, 2002, 12:24 PM
cyborg

1 Attachment(s)

Here's a beta version of the game.....the gfx are stole from DXball, but im gonna make my own later... ;)
Dec 11th, 2002, 04:40 PM
cyborg

1 Attachment(s)

Ok...I've got some errors that i hope anyone of you can find...

I've added border loading, but the collition detection is a bit wrong...

1. Sometimes the ball gets stuck and moves along one of the sides
2. Sometimes (maybe all the time (not sure)) when the ball bounces on the roof, the new angle is wrong!
3. When the ball moves through the bricks, it sometimes moves between two bricks...

The zip contains the source and the compiled program with 2 test borders....
Dec 11th, 2002, 06:53 PM
NoteMe

Quote:

1. Sometimes the ball gets stuck and moves along one of the sides

I can't see what you are meaning by this...But it is wery easy to get the ball to move from left to right and back again without moving very much in Y direction. And this way it will hit all bricks...

Quote:

2. Sometimes (maybe all the time (not sure)) when the ball bounces on the roof, the new angle is wrong!

I can't see anything wrong with the angle when it hits the roof...

Quote:

3. When the ball moves through the bricks, it sometimes moves between two bricks...

Yes you need bether collision detection. I havn't looked at you code, but I'm guessing that you are only checking the left property of the ball. You would have to add the width to and check for the whole ball...

I'm so tired no so I won't try to give you a solution now....but I will see what I can do tomorow...

Good Night Cyborg...
Dec 11th, 2002, 06:53 PM
NoteMe

BTW I forgot to tell you, it's a nice game, and the ball moves smooth...;)
Dec 12th, 2002, 08:39 AM
cyborg

Thanks!

Sometimes when the ball hits one of the sides, it doesnt bounce, it just follows the side in the same speed as before!

The collition detection checks the whole ball!

If i set the startangle on the ball to 180 it should move straight up, but it moves a bit to the right....

If i get the ball to bounce straight up, it should move straight down after hitting the roof, but it moves a bit to the left...
Dec 12th, 2002, 08:58 AM
cyborg

Quote:

Originally posted by NoteMe
I can't see what you are meaning by this...But it is wery easy to get the ball to move from left to right and back again without moving very much in Y direction. And this way it will hit all bricks...

Fixed...
Dec 14th, 2002, 08:51 AM
cyborg

1 Attachment(s)

If you care....
here's a new and improved version! :p
Dec 14th, 2002, 09:05 AM
NoteMe

Quote:

Originally posted by cyborg
If you care....
here's a new and improved version! :p

I never stop caring about your games ;). This game is turning out great. But I'm not sure if it is only my machine or if it is because I have a lot of apps running in the background, but I don't think the ball moves that smooth anymore, and the it seems like the speed is increasing after the ball has hit the "roof" and some bricks (or is this just something I imagine my self??)...

Nice game..
Dec 14th, 2002, 09:16 AM
cyborg

the speed is allways incresing untill it reaches a certain value...
the new angle gets wrong after hitting the roof and the bricks...

maybe it doesnt move that smooth anymore, but that can be fixed...
the colition detection that i've made it checking all pixels on the ball every 10th millisecond....
i think that code can be improved...i'll look into that in a few days!
Dec 14th, 2002, 09:24 AM
NoteMe

Quote:

Originally posted by cyborg
the speed is allways incresing untill it reaches a certain value...
the new angle gets wrong after hitting the roof and the bricks...

maybe it doesnt move that smooth anymore, but that can be fixed...
the colition detection that i've made it checking all pixels on the ball every 10th millisecond....
i think that code can be improved...i'll look into that in a few days!

Looking forward to it...you are starting to be good at game programming...:D
Dec 14th, 2002, 09:33 AM
cyborg

thanks very much!
i just love to make games :)
Dec 14th, 2002, 07:21 PM
alkatran

Hmm

I haven't looked at your code, but when you said about your collision detection.. Ok.. so you have a ball and a brick... the collision detect should use angles and distance.. ..

What you need is to get the distance between the ball and al bricks. Any bricks with a distance below the balls speed (add a bit of leway.. just in case) are checked for collision.

To check for collision:
Get the angle to the 4 corners of a brick
If the ball is going to hit the brick, it's movement angle will be within those angles (Don't to compensate for ball size!!)..so..

Let's assume that A(1) = 45 (top left), A(2) = 40 (bottom left), a(3) = 35 (top right) and A(4) = 30 (bottom right)
*its up to you to get angles

First, you find the lowest number...

Low = 360
for b = 1 to 4
if a(b) < low then low = a(b)
next b

then the highest..

High = 0
for b = 1 to 4
if a(b) > High then High = a(b)
next b

and near finally:
If Low <= High *(this is explained below)* then
if BallAngle > Low and BallAngle < High then msgbox " BOOM "

ELSE

*Because 360 = 0, 361 = 1 in angles.. you could potentially get a *5 and a 355.. where 355 would actually be the lower one.. So *just do:

for b = 1 to 4
a(b) = a(b)+180
if a(b) > 360 then a(b) = a(b) - 360
next b
**redo low-high here
**redo angle check, dont forget to change Ballangle (+180 *-360)
for b = 1 to 4
a(b) = a(b)-180
if a(b) < 0 then a(b) = a(b) + 360
next b
End if

THIS IS UNTESTED AND I MADE IT UP HERE, NO GUARANTEES ON BUG-FREE.

Ok, now for colliding with sides:

BallAngle = AngleofWhatYouHit-Ballangle

So if your headed straight up (90) and hit the ceiling (0) you will get -90 (270), which is the way it should be.

If you hit side (90) and are going at 45 (up+right) it will change to 135 (up+LEFT)
Dec 15th, 2002, 07:53 AM
cyborg

Thanks...

I'll see if i can get something like that into the game later on...

The biggest problem now is that something get wrong with one type after finishing a level...i cant redim it...

And another big problem is when the ball hits something, its new angle is not correct...

When the ball hits the top, i use this code:
Ball(i).Angle = 180 - Ball(i).Angle

When it hits one of the sides, i use this:
Ball(i).Angle = -Ball(i).Angle
Dec 15th, 2002, 08:45 AM
/\/\isanThr0p

alright since you have to calculate the x and the y component of your movement every time you should directly store those values instead of doing the same calculation over and over again. that way collision gets easier too. if it hits the side take the x-component *-1 if it hists the top take the y-component *-1. If you hit something that requires you to change the angle you can always get the angle back from the x and the y component using the tan but I would store the angle anyways (again to save calculations and avoide rounding mistakes and lines of code)
Dec 15th, 2002, 09:17 AM
alkatran

Are you doing Sin for X and Cos for y? or Cos for x and Sin for y?
Dec 15th, 2002, 09:19 AM
NoteMe

1 Attachment(s)

Can you tell me what the angle is her (from what to what)...

Quote:

When the ball hits the top, i use this code:
Ball(i).Angle = 180 - Ball(i).Angle

Look at my drawing and tell me...because on my drawing I have marked angle A and B but I can't see your code calculation those...or am I not able to see it...:D

http://www.vbforums.com/attachment.p...postid=1300918
Dec 15th, 2002, 09:27 AM
alkatran

Top is 180, Ball.angle on left of equation is B, Ball.angle on right of equation is A

He should be using 0 and not 180 I think
Dec 15th, 2002, 09:29 AM
NoteMe

Quote:

Originally posted by alkatran
Top is 180, Ball.angle on left of equation is B, Ball.angle on right of equation is A

He should be using 0 and not 180 I think

I still can't see what he is thinking...because if the angle moves from A to B, and in A it has 60degrees, then he want an angle of -60degress or 300degress after the hit...
Dec 15th, 2002, 10:54 AM
/\/\isanThr0p

well all of that wouldn't be an issue using the x and the y component :)
Dec 15th, 2002, 10:55 AM
NoteMe

Quote:

Originally posted by /\/\isanThr0p
well all of that wouldn't be an issue using the x and the y component :)

I know, thats how I make games ;)
Dec 15th, 2002, 02:42 PM
cyborg

1 Attachment(s)

As you can see on the pic, 0 degrees is straight down.

Then you can see that the angle A + B = 180, so B = 180 - A.

http://www.vbforums.com/attachment.p...postid=1301129
Dec 15th, 2002, 02:45 PM
cyborg

i didnt want to use radians in this game, because im always getting trouble when the ball is moving many Y values in one X value...then the ball moves too fast!
Dec 15th, 2002, 02:56 PM
NoteMe

Quote:

Originally posted by cyborg
i didnt want to use radians in this game, because im always getting trouble when the ball is moving many Y values in one X value...then the ball moves too fast!

This doesn’t make sense. You can have the exact same X and Y movements using Rad, but I have to admit that I like to use Degrees too...

And the calculations of the angle looks fine with me, so I think that there has to be another place in the code there is a BUG...But I can't see the ball moving in the wrong direction on my PC ;)
Dec 15th, 2002, 03:13 PM
cyborg

Open up the code, search for this line:
Ball(1).Angle = 180 - 10

change it to: Ball(1).Angle = 180

That should make the ball move straight up when shooting it the first time! but it doesnt!

and if you bounce the ball to move straight up, it should move straight down after hitting the top, but it moves a bit to the left!

I have no idea where the error can be!
Dec 15th, 2002, 03:15 PM
cyborg

lol! Just 1 sec after posting the last post i found the error!
Pi was defined in a long, making it to only 3, not 3.14........

Can anyone help me with this code?

This is used in the collition detection to check the new direction of the ball (which side of the brick it hits)

TempCol holds the X value of the brick that the ball hits
TempRow holds the Y value of the brick that the ball hits
These are not in pixels, but in count of bricks...
One brick are 30*15 pixels

X holds the X value of the ball when hitting a brick
Y holds the Y value of the ball when hitting a brick

VB Code:

If X < TempCol * 30 - 29 Or X > TempCol * 30 - 2 Then
            If X < TempCol * 30 - 28 Then
                'hit left side
                Form1.ChangeDirection BallNr, "L"
            ElseIf X > TempCol * 30 - 2 Then
                'hit right side
                Form1.ChangeDirection BallNr, "R"
            End If
        Else
            If Y < TempRow * 15 + 29 Then
                Form1.ChangeDirection BallNr, "U"
            Else
                Form1.ChangeDirection BallNr, "D"
            End If
        End If

This code is not correct, and there must be a better way of doing this...

Dec 15th, 2002, 04:51 PM
cyborg

1 Attachment(s)

Here's a zip with the program and source...fully commented..
Did some fixes to it...
Dec 16th, 2002, 07:41 AM
alkatran

1 Attachment(s)

umm

When I went from level 1 to 2.. there was a block that wasn't ever detected as hit.. it didn't fit pattern either, here's a picture:
Dec 16th, 2002, 07:48 AM
NoteMe

Re: umm

Quote:

Originally posted by alkatran
When I went from level 1 to 2.. there was a block that wasn't ever detected as hit.. it didn't fit pattern either, here's a picture:

http://vbforums.com/attachment.php?s=&postid=1301735

Nice shooting...:D
Dec 16th, 2002, 08:25 AM
cyborg

Yes i know...
just found out what was wrong!
Dec 16th, 2002, 07:58 PM
cyborg

Does anyone have an idea on how to fix that code (some posts up)?
Dec 17th, 2002, 10:55 AM
alkatran

umm

I'm not really sure, I like my system :p, but don't forget to increase the 'range' of detection as ball speeds up (and check angle, so it doesn't catch a right hit on left side)