Math Problem

Hello!

Im currently trying to code a new enemy for my 2d space shooter game. It should be a chain that osciallte from left to right.



Hope this graphic helps you to understand what i want to to.

I tought it should be possible with Sin/Cos Commands. But it won't work the way i want it to. Here is the code:

Graphics 800,600
SetBuffer BackBuffer()

While Not KeyDown(1)

	Cls

	tt=tt+1
	If tt>360 Then tt=0
	
	For i=0 To 50
		Plot 400+Sin(tt)*i,50+i*10+Cos(tt)*i
	Next
	
	Line 400,50,400,600 ;Axis
	Flip
Wend

something like that ?

Graphics 800,600

SetBuffer BackBuffer()

While Not KeyDown(1)
	If KeyHit(57) Then typ = typ +1
	typ = typ Mod 2
	
	Cls

	tt=tt+1

	;If tt>360 Then tt=0
	
	;modulo is better ... i think
	tt = tt Mod 360
	
	For i=0 To 50
		Select typ
		Case 0
			;like that ?
			x = 400 + Sin(tt) * 400
		Case 1
			;or like that ?
			x = 400 + Sin(tt+((i/50.0)*360)) * 400
		End Select
		
		y = 50+i*10
		
		Plot x,y

	Next
	
	Line 400,50,400,600 ;Axis
	
	Text 10,10,"Hit space to switch type"
	Flip
Wend

Hello,

thank you for your post. But your code event doesn't that what I want to :-)

The left-right movment is correct, but i think in a chain that swings each part also moves a little bit up and down.

Imagine you hold a chain, than all parts move like on a path of a circle I think.

Do you know what i mean?

Graphics 800,600 
SetBuffer BackBuffer() 

d=1
i=-90

While Not KeyDown(1) 

Cls

i=i+d 
For o=1 To 100 Step 10

Plot 400+Sin(i)*o,300+Cos(i)*o 

Next

If Abs(i)=90 Then d=-d

Line 400,0,400,600 ;Axis 

Flip 
Wend

and

Graphics 800,600 
SetBuffer BackBuffer() 

d=2
i=-90
o#=10

Cls


Line 400,0,400,600 


While Not KeyDown(1) 

i=i+d
o#=o#+0.05

Plot 400+Sin(i)*o#,300+Cos(i)*o# 

If Abs(i)>=90 Then d=-d

Flip 
Wend 

or

Graphics 800,600 
SetBuffer BackBuffer() 

d#=80
i#=-90
o#=10

Cls


Line 400,0,400,600 


While Not KeyDown(1) 

i#=i#+d#/o#
o#=o#+0.1

Plot 400+Sin(i#)*o#,300+Cos(i#)*o# 

If Abs(i#)>=90 Then d#=-d#

Flip 
Wend 

Hey, cool... this looks much better, but still one problem ;)

when the direct change the speed should getting slower and after direction it should accelerate again.

i've tried it that way, and i think it will work this way. Anyway, thank you very much for the help, and if you still have improvements it would be great if you post it here :-)

Graphics 800,600 
SetBuffer BackBuffer() 

d#=1
i#=0

While Not KeyDown(1) 

Cls


Text 10,10,i
Text 10,30,d

i=i+d 

For o=1 To 100 Step 10
	Plot 400+Sin(i)*o,300+Cos(i)*o 
Next

If i>45 Then d=d-0.01
If i<-45 Then d=d+0.01

If d>1 Then d=1
If d<-1 Then d=-1

Line 400,0,400,600 ;Axis 

Flip 
Wend

something like this then

Graphics 800,600 
SetBuffer BackBuffer() 

d=20
i#=-90

Cls

While Not KeyDown(1) 

a#=(1/Abs(i)*d)
If a#>1 Then a#=1

i#=i#+a#

Cls 
Line 400,0,400,600 
Plot 400+Sin(i#)*50,300+Cos(i#)*50

If Abs(i)>=90 Then d=-d

Text 0,0,1/Abs(i#)*d
Flip 
Wend 

If you want correct pendule physics try this:

Graphics 800,600 
SetBuffer BackBuffer() 
d=1
i#=-90
s#=0
While Not KeyDown(1) 
Cls
s=s-Sin(i)*.01
s=s*.999 ;Slowing the speed
i=i+s
For o=1 To 100 Step 10
Plot 400+Sin(i)*o,300+Cos(i)*o 
Next
Line 400,0,400,600 ;Axis 
Flip 
Wend